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Watershed Management for Potable Water Supply: Assessing the New York City Strategy (2000)

Chapter: 9 Nonpoint Source Pollution Management Practices

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Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

9
Nonpoint Source Pollution Management Practices

Nonpoint source (NPS) pollution is widely dispersed in the environment and is associated with a variety of human activities. These activities produce pollutants such as nutrients, toxic substances, sediment, and microorganisms that may be delivered to nearby waterbodies following rainfall or directly via atmospheric deposition. Under pristine conditions, land generally has an enormous capacity to remove pollutants from rainwater. For example, research in the Catskills has shown that undisturbed forests can remove as much as 90 percent of the nitrogen from rainwater before it can reach nearby streams (Lovett et al., 1999). However, activities that produce NPS pollution also cause changes in vegetative cover, disturbance of soil, or alteration of the path and rate of water flow. These physical changes may prevent the land from naturally removing pollutants in stormwater. Thus, there are two interacting effects of NPS activities: (1) production of a pollutant and (2) alteration of the land surface in a way that increases pollutant loading to receiving waters. The goals of NPS pollution best management practice (BMPs) are to maintain or restore the ability of the land to remove pollutants and to limit production of the pollutant.

The intent of this chapter is to evaluate the BMPs that are being used to control NPS pollution in the Catskill/Delaware watershed. Because most BMPs are implemented within the framework of an NPS pollution control program, this chapter reviews and critiques a variety of such programs (1) the Watershed Agricultural Program, (2) the Watershed Forestry Program, and (3) the Stormwater Pollution Prevention Plans. Conclusions and recommendations are made for the BMPs and for the NPS pollution control programs in general.

Table 9-1 lists potential nonpoint sources, priority pollutants, and some of the qualitative and quantitative criteria that can be used to rate NPS pollution

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

TABLE 9-1 Nonpoint Sources, Priority Pollutants, and Potential Criteria for Evaluating NPS Pollution in the New York City Watersheds (Not all table entries are considered in this report)

Nonpoint Sources

Priority Pollutants

Evaluation Criteria

• Agriculture

• Phosphorus

• Total land area covered under the MOA

• Urban stormwater

• Organic carbon compounds

• Export coefficient

• Construction/roads

• Turbidity/TSS

• Best management practices used

• Forestry

Cryptosporidium

• NYC DEP performance monitoring data of BMPs

• On-site sewage treatment and disposal systems

Giardia

• Are BMPs implemented using best available technology?

• Atmospheric deposition

• Fecal coliforms

• National performance/general effectiveness

• Does BMP efficiency depend on regular maintenance?

• Are there appropriate institutions to ensure full-scale implementation?

control programs. This review is not comprehensive; for example, atmospheric deposition is not specifically addressed. This is because nitrogen loading is not primary pollutant associated with atmospheric deposition, and nitrogen loading is not a particular concern in the watershed region. In addition, atmospheric deposition of pollutants onto the land surface might be treated by the BMPs designed to treat other sources of nonpoint pollution.

NONPOINT SOURCES PROGRAMS

NPS pollution is a problem that is becoming increasingly important in the Catskill/ Delaware watershed, as evidenced by at least 30 different programs developed to reduce its impact. In fact, the New York City Department of Environmental Protection (NYC DEP) identifies almost all the regulations in the Memorandum of Agreement (MOA) as dealing with NPS pollution (NYC DEP, 1998a). Because these programs are not integrated into one overall program, there can be some confusion when trying to evaluate the methods being used to manage NPS pollution in the New York City watersheds. Sources for NPS pollution programs that affect the New York City water supply include (1) the Watershed Rules and Regulations of the MOA, (2) the May 1997 Filtration Avoidance Determination (FAD), (3) the Watershed Protection and Partnership Programs of the MOA, and (4) various State programs.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

Watershed Rules and Regulations

The Watershed Rules and Regulations contain most of the NPS pollution programs conducted by NYC DEP. These programs include three basic mechanisms for controlling NPS pollution (NYC DEP, 1998a): (1) strict performance standards applied to activities that produce NPS pollution, (2) a review and approval process for activities that produce NPS pollution, and (3) prohibition of certain activities in a ''setback" region between the activity and nearby waterbodies.

Performance standards exist for wastewater treatment plants (WWTPs) that discharge to the subsurface but not for on-site sewage treatment and disposal systems (OSTDS), stormwater BMPs, agricultural BMPs, and forestry BMPs. Although it is technically feasible to monitor performance standards for all these activities, it can be difficult and expensive because of the diffuse and episodic nature of pollutant transport.

The Stormwater Pollution Prevention Plan (SPPP) is a good example of a review and approval process used to control NPS pollution. All construction activities affecting more than five acres must prepare an SPPP and receive approval before the project commences. Finally, setbacks have been designated for a range of activities, including OSTDS construction, hazardous materials storage, the construction of impervious surfaces, siting of landfills, and residential pesticide application. These setback distances, which vary depending on the activity and the type of waterbody nearby, are evaluated in detail in Chapter 10.

Filtration Avoidance Determination and the Watershed Protection and Partnership Programs

The FAD and the Watershed Protection and Partnership Programs indirectly manage NPS pollution. The FAD requires that Total Maximum Daily Loads (TMDLs) be calculated for the reservoirs and that a phosphorus offset pilot program be developed, both of which require implementation of NPS pollution BMPs. The Watershed Agricultural Program is included under the FAD, although agricultural BMPs are not specified. Finally, the Watershed Protection and Partnership Programs include the Watershed Forestry Program and the Stream Management Program, which discuss control of NPS pollution.

New York State NPS Pollution Programs

NYC DEP participates in a number of State activities relating to NPS pollution, including the New York State Nonpoint Source Coordinating Committee. NYS DEC is the primary state agency for controlling NPS pollution as part of its enforcement of the Clean Water Act (CWA). In many cases, the Watershed

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

Rules and Regulations mirror provisions in State regulations, and NYC DEP oversight provides additional protection.

AGRICULTURE IN THE CATSKILL/DELAWARE WATERSHED

Agriculture, the predominant industry in the Catskill/Delaware watershed, is concentrated primarily in the Cannonsville and Pepacton watersheds. As shown in Figure 9-1, farms are relatively evenly distributed across the Delaware watershed, with many found close to major tributaries such as the West Branch of the Delaware River. Farms become more sparse in the eastern portion of the watershed because of more mountainous terrain and relatively poor soils.

Ninety (90) percent of the 351 farming operations in the Catskill/Delaware watershed are dairy farms, most of which have between 50 and 200 animals.1 Most farms in the region also support crop production and contain significant tracts of forest. Although dairy cows are the predominant animal at farms participating in the Watershed Agricultural Program, a wide variety of other animals can be found (Table 9-2).

Watershed Agricultural Program

The Watershed Agricultural Program (WAP) is a voluntary program intended to standardize and improve environmental practices among watershed farmers. Because of the WAP, all agricultural activities in the Catskill/Delaware watershed are exempt from MOA regulations such as setback distances, discharge permits, and rules regarding pesticide application. To date, many in the farming community and most of those concerned about the quality of New York City drinking water have been ardent advocates of the program. This broad support is testimony to the strong affinity for agriculture as an important economic endeavor in the Catskill/Delaware watershed region.

The WAP is administered by the Watershed Agricultural Council (WAC), a grassroots organization composed of farm, agribusiness, and environmental leaders. Since 1993, the primary role of the WAC has been to review and approve changes being made on individual farms to improve the water quality of nearby receiving waters (both surface and subsurface).

One of the unique features of the WAP is its strong connection to basic research being conducted by Cornell University on the sources and transport of pollutants from agricultural practices. With funding usually supplied by NYC DEP, scientists at Cornell have studied the hydrology, phosphorus transport, parasitology, and economics of the Catskill/Delaware watershed. Cornell

1  

 "351" refers only to those farms having a gross annual salary of at least $10,000, making them eligible for the Watershed Agricultural Program.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

FIGURE 9-1 Farm locations in the Catskill/Delaware watershed. Courtesy of the NYC DEP.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

TABLE 9-2 Livestock Types and Numbers in the Catskill/Delaware Watershed

Livestock Type

Number

Mature Dairy

12,636

Dairy Heifers

8,758

Chickens

2,655

Beef Cattle

1,566

Veal Calves

790

Sheep

569

Horses

565

Deer

375

Pheasant

250

Other

284

 

Source: NYC DEP (1997a).

researchers have also developed a mix of very useful process-based and empirical models to use as planning tools or to use in support of the planning process. Thus, the WAP has been in a position to apply research findings to actual farm practices at an early stage in the process. The WAP has largely focussed on understanding the role of agriculture in generating pathogens and phosphorus and on application of BMPs for pathogen and phosphorus control. Two activities that may change the overall focus of the program are manure export and the Conservation Reserve Enhancement Program.

Whole Farm Plans

Whole Farm Plans are comprehensive strategies for controlling potential sources of pollution at individual farms. For those farmers that participate in the WAP, a Whole Farm Plan, which addresses their specific problems and needs, is developed by a planning team consisting of the farmer and representatives from local Soil and Water Conservation Districts, the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), and the Cornell Cooperative Extension. The contributions of each organization to the Whole Farm Plans are described in Table 9-3, and the 11-step Whole Farm Plan process is outlined in Table 9-4. To date, 199 Whole Farm Plans have been completed and approved by the WAC (NYC DEP, 1999a).

The main purpose of the Whole Farm Plan is to develop and implement BMPs that address pressing environmental concerns while being compatible with the farmer's mission and objectives. Specific BMPs are evaluated and approved

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

TABLE 9-3 Organizations Involved in Whole Farm Planning

Organization/Party

Role

Farmer

The focus of the Watershed Agricultural Program. Participation is voluntary.

NYC Department of Environmental Protection

A source of major funding and technical and administrative support to the WAP. One NYC DEP staff member is a member of the WAC.

NYS Department of Environmental Conservation

Ex officio member of the WAC, providing technical expertise on nonpoint source pollution control measures.

USDA Natural Resources Conservation Service

A source of technical and scientific expertise for the WAP. Its role in the watershed predates the WAP.

Soil and Water Conservation Districts

Grassroots organizations created by individual counties to supply technical expertise to farmers on conserving soil/water.

Cornell Cooperative Extension

Technical and managerial expertise to farmers as part of New York State's land grant university, Cornell University.

Cornell University

Original research focusing on water resources and pollution prevention in the New York City watershed.

 

Source: WAP (1997).

TABLE 9-4 Steps in the Whole Farm Plan Process

Step

Description

1

Identify farm mission, objectives, business plan, and resources, both short-term and long-term.

2

Inventory and analyze water, soil, air, plant, and animal resource information.

3

Determine the priority water quality (and other) issues for the farm.

4

Identify practices (BMPs) to address the priority water quality (and other) issues.

5

Evaluate the effects of these practices on water quality (and other) issues from Step 3.

6

Identify adequate alternatives that satisfy the WAP's water quality criteria.

7

Quantify the economic and management effects of the alternative practices.

8

Select and integrate the practices to be included in the Whole Farm Plan. Submit the plan to the Soil and Water Conservation District and the WAC for approval.

9

Develop tactical plans to ensure successful implementation of the approved Whole Farm Plan.

10

Implement the Whole Farm Plan.

11

Assist, monitor, and evaluate implementation of the Whole Farm Plan and evaluate progress toward addressing the priority issues.

 

Source: NYC DEP (1997a).

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

by the planning team prior to their implementation. Once a plan is approved, the planning team develops a strategy for implementing the plan and measuring its success. Monitoring for changes in water quality at this stage is an ideal approach to measuring the impact of farm BMPs. However, in some cases the necessary monitoring techniques do not exist, or the staff or technical equipment is not available to conduct the monitoring. Thus, extensive monitoring of soil and water quality does not take place on a regular basis at all farms participating in the program. Planning teams ensure maintenance of the BMPs via field inspection and try to keep abreast of improvements in technology that should be considered for use.

Focus of Agricultural Best Management Practices

The BMPs that have been chosen for the farms in the Catskill/Delaware watershed are a direct outgrowth of the priority pollutants and the specific environmental problems present. They can be classified as one of three general types: (1) barriers to pollutant transport (source control), (2) landscape barriers, and (3) stream corridor barriers. As discussed in Chapter 5, livestock generates pathogens, underscoring the importance of managing manure on farms (NYS WRI, 1997). Nutrients, especially phosphorus, are also priority pollutants in the watershed. Typical phosphorus inputs occur in animal feed and fertilizers; typical outputs include animal waste, plant material, and fertilizer that does not penetrate the soil. Finally, pesticides are potential pollutants in the watershed, and the MOA does not regulate agricultural uses of these compounds.

Common BMPs used in the watershed include barnyard management, improved manure storage, and the separation of calves from cows. A complete list of agricultural BMPs used in the WAP is given below (WAP, 1997):

  • Barnyard water management system

  • Conservation cropping sequence

  • Cover and green manure crop

  • Diversion

  • Fencing

  • Filter strip

  • Grassed waterway or outlet

  • Obstruction removal

  • Pasture and hayland planting

  • Pipeline

  • Planned grazing system

  • Access road

  • Pathogen management

  • Spring development

  • Trough or tank

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×
  • Stock trails and walkway

  • Stripcropping—contour

  • Structure for water control

  • Nutrient management plan (manure spreading based on soil phosphorus recommendations)

  • Pesticide management

  • Subsurface drain

  • Underground outlet

  • Waste utilization (manure management)

  • Windbreak

Measuring Success

Typically, the measures of success for water quality BMPs in agricultural settings have been related to the numbers of practices installed and the numbers of farms participating, an approach that was initially taken by the WAP. Several success metrics for the WAP are included in New York City's waiver from filtration: (1) the number of participating farms, (2) the number of Whole Farms Plans that are developed and approved, (3) the number of Whole Farm Plan implementations, and (4) the number of plans for which an annual evaluation has been completed. These measures were seen as important because of the contentious interactions between watershed farmers and City and State regulators.

The WAP has not been prioritized by targeting specific farms with known pollution problems. Rather, farmers have been allowed (after observing the prototype of ten pilot farms) to join the program on a voluntary basis, regardless of the extent of pollution at their farm. These criteria have resulted in a large number of participating farms (317, over 90 percent of all eligible watershed farms).

The most important measures of program success are monitoring data and other evidence that demonstrate a positive impact of new farm practices on water quality. This approach requires performance monitoring of BMPs, determining pollutant loadings emanating from these BMPs, and modeling the resultant water quality in nearby receiving waters. Unfortunately, linking the performance of BMPs with nearby water quality conditions is much more difficult to accomplish than determining the number of farms in the program or the number of plans implemented.

To use this later approach, more information is needed on (1) the accumulation of pathogens and nutrients in source areas (as suggested in Chapter 6), (2) pathogen and nutrient wash-off from source areas during rainfall (i.e., pollutant loading in overland flow), and (3) transport of pathogens and nutrients through the shallow subsurface prior to reaching waterbodies (i.e., pollutant loading in subsurface flow). As suggested in a recent independent review of the WAP, this

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

approach relies on understanding the baseline pollutant conditions in the watershed and the receiving waters (CTIC, 1998).

Monitoring of farm conditions is currently concentrated at only two locations–the Shaw Road control area and Robertson Farm—in the hope that data gathered at these locations will be applicable to the entire Catskill/Delaware watershed. This monitoring is based on a modified paired watershed approach to understanding the integrated effects of Whole Farm Plan implementation rather than being based on monitoring of individual BMPs. Preliminary data gathered since 1996 indicate that there are significant differences between the loading rates of different pollutants at the farm and at the control area (WAP, 1997). However, additional research must be conducted before these data can be used.

Analysis of the Watershed Agricultural Program

The whole farm planning approach taken by the WAP represents a significant advance compared to the standard conservation planning done by USDA-NRCS and associated agencies. Because of the level of resources available to the WAP and the early recognition that new scientific information was needed to accomplish the Whole Farm Plans, the WAP has been instrumental in attempting to integrate scientific information and farm plans for controlling nonpoint source pollution.

Although the accomplishments of the WAP and the whole farm planning projects are substantial, gaps in knowledge, implementation, and monitoring underscore the difficulty of determining the level of ecological and environmental sustainability provided at the watershed scale by a suite of agricultural BMPs. As discussed below, specific areas that must be addressed to improve the whole farm planning process include the transport and loading of phosphorus (including issues of scale, modeling, and monitoring) and the transport of microbial pathogens.

Transport and Loading of Phosphorus

There have been numerous efforts over the last 20 years to study nutrient loadings (particularly phosphorus) from agricultural lands to the Cannonsville Reservoir via the West Branch of the Delaware River (WBDR), other tributaries, and subsurface flow. As described in Box 9-1, these efforts have revealed a wealth of information about the relative sources of phosphorus, average phosphorus concentrations in different types of runoff, and the efficacy of certain agricultural BMPs for reducing pollutant loading from some farm sources. Despite these efforts, there are still no scientifically based nutrient load reductions developed for the Cannonsville watershed. The following section discusses the importance of such requirements and the information needed to develop them.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

BOX 9-1
The Model Implementation Program of the 1980s

Phosphorus has been of considerable interest in the New York City water supply watersheds, especially in the West Branch of the Delaware River–Cannonsville watershed, for at least two decades. The first national demonstration of agricultural BMPs as a means of water pollution control was undertaken by USDA and EPA in 1977 as part of the Model Implementation Program (MIP). One of the MIP sites was the West Branch of the Delaware River (WBDR). MIP focused on control of dissolved phosphorus from animal wastes (particularly barnyard runoff), manure-spreading schedules, and conservation practices including waste storage, stripcropping, conservation tillage, conservation cropping, cover cropping, critical area planting, woodland improvement and harvest, and tree planting.

As part of the MIP, barnyards on 275 farms were prioritized for treatment based on their distance from defined watercourses. Out of 154 high-priority barnyards, 91 were treated with BMPs. The practices applied included diversions, open drains, water-control structures, roof gutters, grading, fencing, livestock exclusion from streams, and pavement of heavily used areas. Treatment of some cropland with phosphorus and with erosion-control measures was accomplished, and an educational and advisory program for silviculture was established.

Cornell University and NYS DEC subsequently studied the effects of the MIP in the Cannonsville watershed (Brown et al., 1984). As a result, a great deal was known about the potential sources of phosphorus, the appropriate analysis methods for phosphorus, and phosphorus transport mechanisms in agricultural watersheds. The MIP first focused on changing the size and management of dairy barnyards. Detailed monitoring data showed that barnyards can be treated to achieve a high level of phosphorus control (50–90 percent load reduction). Diversion of water flow from areas above the barnyard was found to be a critical factor in controlling runoff from barnyards. However, even though dairy barnyards were a significant source of phosphorus, the studies concluded that the

Developing Phosphorus Reduction Goals. Two components are needed to assess the impact of farm activities on nearby water quality: (1) a water quality model for the Cannonsville Reservoir that predicts long-term phosphorus concentrations in relation to varying inputs and (2) phosphorus loadings from adjacent agricultural areas, considering both surface and subsurface contribu-

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

barnyard control would achieve less than a 5 percent reduction in overall dissolved phosphorus loading (Brown et al., 1984). MIP-related studies also modeled the effects of manure-spreading schedules, which indicated that manure scheduling could lead to an average reduction of total phosphorus loading of 35 percent.

A watershed-based model was used to show that direct runoff (both surface and subsurface), WWTPs, and baseflow accounted for 38, 23 and 33 percent, respectively, of dissolved phosphorus loadings and 70, 10, and 16 percent, respectively, of total phosphorus loadings to the Cannonsville Reservoir (Brown et al., 1984). The 30-month record developed for this study showed that more than 85 percent of dissolved phosphorus, total phosphorus, and sediment loadings occurred during periods of snowmelt and rainfall in January to March. The model illuminated the most relevant parameters for assessment of BMPs. Average concentration of dissolved phosphorus in direct runoff both surface and subsurface) estimated from load vs. runoff regressions at the small watershed scale was found to be the best parameter for gauging the effectiveness of a phosphorus control program. Interestingly, a substantial portion of the dissolved phosphorus budget (39 percent) for the entire WBDR was due to groundwater inputs to streamflow, considered at the time "to be largely uncontrollable" (Brown et al., 1984).

Based on manure scheduling (Robillard and Walter, 1984b) and a watershed-scale model of the WBDR (Haith et al., 1984), Brown et al. (1984) found that the spreading of manure during winter was a major source of dissolved phosphorus in surface runoff in the WBDR. Another major phosphorus source identified in this work was flooded cropland along the WBDR itself. Recommendations were that (1) efforts should focus on cropland and manure-management practices in the watershed, (2) field-scale investigations were needed to understand phosphorus losses from upland farming in the watershed, and (3) barring changes in land use or agricultural practices, a concentration of 0.23 mg/L could be used to estimate dissolved phosphorus in direct runoff. This estimate for dissolved phosphorus in surface runoff was used in some of the modeling studies undertaken in 1997 (NYC DEP, 1997a).

tions. Several issues regarding reservoir water quality modeling must be addressed. First, as suggested by others (CTIC, 1998), monitoring and modeling must take both dissolved and particulate phosphorus into account. The Cannonsville Reservoir regularly exceeds the water quality standard for total phosphorus (20 µg/L), although concentrations of dissolved phosphorus entering

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

the reservoir have decreased from the 1980s to the 1990s by 52 percent (CTIC, 1998).

Auer et al. (1998) reports that most of the phosphorus (95 percent to 97 percent) available to algae in the Cannonsville Reservoir comes from soluble phosphorus inputs from the WBDR. These results should be used to guide the development of a comprehensive model of nutrient/phytoplankton dynamics in the reservoir. This would allow the development of a load management strategy as part of the WAP and TMDL process.

The WAP and New York City should consider using the existing information developed from both the phosphorus cycling models and the TMDL process to develop specific phosphorus load reduction targets for the Cannonsville watershed. Scientifically based load reduction targets would (1) provide an endpoint to be reached in the planning and implementation process of the WAP, (2) be a quantifiable measure of success, and (3) provide feedback to the process of BMP application during whole farm planning. If loads were unequally distributed among subwatersheds, the monitoring of subwatersheds could be related to specific load reduction goals and the effectiveness of specific agricultural BMPs.

Monitoring to Document Success. The second goal mentioned above was to determine phosphorus loadings from adjacent agricultural areas, considering both surface and subsurface contributions. This task requires that individual BMPs (or systems of BMPs) be monitored for their effectiveness in reducing pollutant loadings. Because of technical limitations, such an approach has not traditionally been taken in farm management. Rather, it is more common to ensure that BMPs use Best Available Control Technology (BACT) and simply assume certain BMP removal rates. As suggested by others (CTIC, 1998), new techniques will be needed in order to demonstrate that agricultural BMPs can meet load reduction goals.

Although a large number of BMPs have already been installed and Whole Farm Plans have been implemented on 198 farms, there is very little known about the net result. Monitoring data are available for the Robertson Farm and Shaw Road sites for a two-year period prior to BMP installation at Robertson Farm (Pre 1 and Pre 2) and for the first year of postimplementation (Longabucco et al., 1999). At both locations, stream discharge and precipitation are monitored continuously, and concentrations of pollutants in stream discharge are regularly monitored, including three forms of phosphorus, three forms of nitrogen, organic carbon, suspended solids, Giardia, and Cryptosporidium. As expected, loading rates of most pollutants are higher at the farm (WAP, 1997; Longabucco et al., 1999). NYC DEP has found that most of the pollution on Robertson Farm emanates from a small, heavily used area. Practices implemented on Robertson Farm include manure storage, spreading schedules based on hydrologic sensitivity, tile drainage of wet fields, and diversion of milkhouse waste discharge away from streams.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

The use of small, paired watersheds such as the Robertson Farm versus Shaw Road comparison is a good prototype for the WAP and NYC DEP to follow. According to the first year of monitoring results after the implementation period, the Whole Farm Plan has reduced certain loadings, especially soluble reactive phosphorus loading. However, as noted by the authors (Longabucco et al., 1999), one year of postimplementation monitoring data is insufficient to make conclusions about the success or failure of the Robertson Farm Plan. It should be noted that monitoring was suspended from May 1995 until fall 1996 during the implementation of BMPs. Future monitoring efforts should include the implementation period because the first year of postimplementation data show increases in total suspended solids and particulate phosphorus, attributed to construction activities. Understanding the impact of these construction activities should be part of evaluating Whole Farm Plan implementation.

Although this type of paired-watershed monitoring activity is expensive, more of it is essential for both documentation of the effects of Whole Farm Plans and for determining whether load reduction goals are being met. The paired-watershed monitoring will not yield information on individual BMPs, but it provides the best approach to understanding the aggregate effects of Whole Farm Plans. More watershed sites should be established, with the goal being to compare loads from reference areas and farms before and after implementation of Whole Farm Plans. Such data can later be used to test models of loadings from farm-scale watersheds. The primary determinants of research cost are the number of samples analyzed and the numbers and types of constituents. Flow proportional sampling on more sites would yield more useful information with a lower marginal cost.

The WAP should consider contracting with appropriate agencies to set up a monitoring system with the following attributes: (1) a series of representative reference (forested) watersheds that will provide comparisons for all agricultural watersheds, (2) preimplementation, implementation, and postimplementation monitoring for a representative set of agricultural watersheds, (3) selection of farm-scale watersheds that represent the variety both of the type and the intensity of BMPs being used (these may or may not be just one farm, as long as use of BMPs can be quantified), and (4) use of flow proportional sampling, instead of daily sampling, with the basic sample interval being weekly. Thus, the sample load per sampling station can be reduced to 50–100 per year, rather that 350–365 per year. Although the monitoring system would involve a substantial commitment of resources, without it there will be no way to quantify the water quality effects of Whole Farm Plans.

Integration of Modeling and Monitoring. The overall goal of modeling is to estimate the effects of Whole Farm Plans on nonpoint source pollution. Models should be clear and explicit in the approaches taken to simulate the effects of BMPs, the generation of nutrient budgets for farms, and the simulation of water-

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

shed-scale results. They must also be tested and validated using monitoring data taken at the field, farm, and watershed scale. Unfortunately, a major limitation to current efforts is the lack of monitoring data from specific BMPs that can be used for model development.

The needed integration of monitoring and modeling can be accomplished using the expanded paired-watershed approach described above. Another approach is to establish a farm on which individual BMPs can be demonstrated and monitored, as was done under the Model Implementation Program (MIP) (see Box 9-1). Although a single demonstration farm could not provide monitoring data for all BMPs, particular high-priority BMPs (as identified by modeling) could be targeted. For example, preliminary modeling efforts indicate that changes in manure-spreading schedules based on manure storage may provide the largest decrease in phosphorus transport (NYC DEP, 1997a). Testing these model simulations might be a priority for a demonstration farm. Although the effectiveness of particular BMP types may change from farm to farm because of site-specific conditions, performance data for specific BMPs would be very useful to the WAP in validating models and formulating future Whole Farm Plans.

Modeling has already played a prominent role in the preliminary evaluation of the farm-scale impacts of WAP. For example, NYC DEP has recently modeled the effects of source barriers and landscape barriers on the transport of pollutants, primarily phosphorus, and has compared model results to field observations at a demonstration farm (NYC DEP, 1997a). The source barriers involved changes in the size and structure of the barnyard, while the landscape barriers included changes in the schedule of manure applications to fields. Modeling results showed that installing barnyard gutters and pads and decreasing the size of the barnyard decreased barnyard runoff by 47 percent and phosphorus export by approximately 30 percent. In addition, variable manure-spreading schedules resulted in 2 percent to 50 percent reduction in phosphorus export. Field observations of barnyard runoff at the demonstration farm, however, did not always corroborate model results. This shows why better integration of modeling and monitoring is needed. For example, monitoring how changes in barnyard runoff routing affect filter areas and adjacent fields could inform the modeling effort.

This type of model-based evaluation must be reinforced by efforts to generate phosphorus load reduction goals, as recommended above. The NYC DEP study describes a useful approach to estimating phosphorus load reduction. However, these estimates are not particularly useful unless there is an overall phosphorus load reduction goal at the watershed scale.

Future Use of Phosphorus Control BMPs. Several years of WAP operation highlight opportunities for prioritizing and coordinating phosphorus control BMPs. First, although not historically done, manure application rates should be based on phosphorus, which is a higher priority pollutant in the Catskill/Delaware watershed and reservoirs than nitrogen. Second, manure storage is one structural

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
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measure that most analyses show should be emphasized. In fact, Robillard and Walter (1984b) indicates that changes in manure-spreading schedules may allow a maximum 35 percent phosphorus load reduction if they are combined with effective manure-storage facilities. There is contradictory evidence about the efficacy of barnyard treatment. Monitoring studies (Robillard and Walter, 1984a) and model estimates (NYC DEP, 1997a) indicate significant nutrient load reductions from barnyard treatments, while estimates of nutrient runoff from watershed studies indicated little effect on overall watershed loading from barnyard treatments (Brown et al., 1984). What is clear from earlier studies is that phosphorus loadings from barnyards are primarily dependent on the amount of runoff rather than on the amount of manure phosphorus in contact with the runoff. This implies that marginal changes in manure phosphorus concentrations would have little or no effect on phosphorus transport from barnyards.

Transport of Pathogens

Other than nutrient reductions, the main goal of the WAP is to establish the risk of viable/infective Cryptosporidium and Giardia to the New York City water supply and reduce pathogen loadings from agricultural areas. Transport of pathogens is a relatively new concern in agricultural watersheds. Hence, there is much less known about the transport and fate of pathogens. The pathogen-related research undertaken by Cornell to support the WAP was, by necessity, oriented toward developing methods for (oo)cyst detection, determining (oo)cyst viability, and determining the sources of (oo)cysts. Although a clear picture has begun to emerge concerning sources, risk factors associated with these sources, and factors affecting the viability of parasites in the environment, little is known about the actual transport of parasites from farms or the importance of agricultural areas as a source of parasites at the reservoir watershed scale (NYS WRI, 1997). A recent modeling study by Walker and Stedinger (1999) suggests that agricultural loading of pathogens to reservoirs is largely dependent on the ability of BMPs to enhance degradation of pathogens before they enter nearby streams.

Current Research Efforts. NYC DEP currently conducts a monitoring program for Giardia and Cryptosporidium at over 50 sites throughout the water supply watershed, including the Robertson Farm and the Shaw Road sites. Preliminary analysis of these data indicates sites influenced by agriculture have a lower incidence of detection of Giardia and Cryptosporidium than do urban watersheds or WWTP effluent, although the differences are not large (NYC DEP, 1998b). Undisturbed watersheds have the lowest incidence of both protozoans. More specific studies have investigated farm animal sources of these pathogens, as described in Chapter 5. Because calves were identified as a major source of parasites, procedures were recommended to segregate calves from cows to prevent cross-infection. At a few farms, greenhouses or separate shelters have been

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

installed to house calves, improve ventilation and bedding conditions, and reduce cow-to-calf contact (NYC DEP, 1997a). Other research has focused on the prevalence and incidence of protozoan infection in entire dairy herds and on management practices that contribute to development and perpetuation of protozoans in dairy herds (NYS WRI, 1997).

Cornell research has also made contributions to understanding the viability of Cryptosporidium oocysts in various farm environments. Laboratory studies show that free ammonia in manure causes significant inactivation of oocysts. The viability of oocysts in calf manure piles was reduced by more than 90 percent in 100 days during late fall and early winter, clearly suggesting that calf manure should be stored prior to spreading (NYS WRI, 1997). Other studies indicate contact with soil material is necessary for more rapid inactivation of oocysts during freeze/thaw cycles. The implications of this research are that winter spreading of manure may require bare soil without snow cover, limiting the time periods when winter spreading can occur.

Future Needs. Because agricultural areas are a significant source of pathogens, monitoring, controlling, and preventing pathogen loading from these areas should be a primary concern of the WAP. Effective management of pathogens requires that (1) sources of (oo)cysts from agricultural areas be identified and quantified and (2) the effectiveness of BMPs in removing pathogens be quantitatively assessed. Although substantial progress has been made in understanding the factors controlling parasite incidence on farms, the state of knowledge does not allow quantitative assessment of changes in pathogen loading to the water supply associated with improved agricultural practices. Thus, the WAP's current approach to parasite risk reduction is to control manure storage in order to maximize exposure of pathogens to detrimental environmental factors and minimize the potential of pathogen transport in runoff, and to maintain a healthy calf-rearing environment (NYC DEP, 1997a).

In support of the first goal, it would be ideal to develop a source term for cysts and oocysts from various types of agricultural practices, especially calf-rearing areas. To accomplish this, the WAP should continue supporting basic research on the transport and fate of (oo)cysts and associated modeling efforts such as the model developed in Walker and Stedinger (1999). The second goal has received limited attention, and as a result much more is known about phosphorus removal by BMPs than about pathogen removal by BMPs. Monitoring of individual BMPs should focus heavily on pathogens or appropriate microbial indicators. This information is critical to making informed management decisions about which BMPs to use at specific farms.

New Directions for the Watershed Agricultural Program

Conservation Reserve Enhancement Program. The Conservation Reserve

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
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Enhancement Program (CREP) involves ''retiring" miles of riparian land from agricultural use and will allow the WAP to effectively manage croplands inundated by floods. Based on field observations (Brown et al., 1984), annual or periodic inundation of manured fields may be a significant problem in manure phosphorus transport. Much of the most productive cropland is located in the active floodplain of the WBDR and has historically received high manure application rates (Brown et al., 1984).

Prioritization of lands within CREP can be difficult, as it depends on voluntary participation. The establishment of riparian forest buffers could lead to changes in land use that last beyond the 10- to 15-year life of a rental agreement. Unless new information is available indicating otherwise, CREP should focus on lands that are frequently inundated. (It should be noted that flow patterns and natural/enhanced levees may cause some of the most frequently inundated land to be away from streams.) Consideration should be given to obtaining permanent easements on these lands to allow them to be maintained in riparian forest buffers after expiration of the CREP contracts.

In evaluating the vegetation on CREP land, the potential for grass filters to fail because of either inundation from floods or inundation by overland flow from barnyard diversions or tile drains should be considered. Grass filters are known to fail under conditions of concentrated flow (Dillaha et al., 1989). These failures have apparently been observed in filter areas installed for barnyard runoff (NYC DEP, 1997a).

Another consideration is whether CREP can be used as a vehicle for achieving voluntary limits on direct livestock access to streams. Although a complete prohibition on direct access may be desirable to maximize water quality (CTIC, 1998), it is unlikely to be achieved. In lieu of a mandatory exclusion and fencing program, incentives within CREP and other cost-share measures such as alternative water supplies and fencing can be employed to enhance compliance.

Manure Export. Manure export is being considered as an alternative in the Catskill/Delaware watershed because of an excess of usable manure. Based on both watershed and field-scale mass balance considerations and on manure-spreading schedule changes, manure export would likely have a large effect on phosphorus transport (NYC DEP, 1997a). The effects of manure export on pathogen loading seem less certain because of the cost of collecting and transporting calf manure separately.

Manure export has several important implications for watershed management. Most importantly, manure should be exported to locations (1) where it is economically feasible given a certain sustainable level of subsidy, (2) where the manure is needed as an agronomic resource, and (3) where there will not be environmental quality problems caused by manure imports. At first analysis, the manure-producing areas of the Catskill/Delaware watershed do not seem to be

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

near areas in need of manure imports.2 Potential agronomic problems in the Catskill/Delaware watershed also warrant consideration. Farmers will need to keep an adequate amount of manure to provide the phosphorus needs of their crops, especially on low-phosphorus fields. If manure resources are exported, farmers may decide to provide phosphorus by adding inorganic fertilizer, which would be an additional (and hence, undesirable) source of phosphorus in agricultural runoff. In short, manure export plans must be carefully considered.

Science Program. The WAP's connection to basic science research has provided significant new information on the sources of Cryptosporidium oocysts and the relation between herd management and oocyst production. In addition, a great deal of knowledge on factors affecting oocyst survival and tracking has been gained. The field- and farm-scale modeling and management tools developed by Cornell University researchers represent significant advances. In order to assess whether agriculture will be able to meet the water-quality goals required of an unfiltered drinking water supply, more research will be necessary. The collaboration between the WAP and basic research should continue until reliable predictions of the following can be made: (1) reductions in pathogen loading rates for specific BMPs applied to dairy farms, (2) reductions in phosphorus loading rates for specific BMPs applied to dairy and other farms, and (3) reductions in watershed-scale loading rates for pathogens and phosphorus for systems of BMPs and Whole Farm Plans.

In order to accomplish these tasks, the science program should explicitly consider the relationship between system function and the management tools under development. An example is the Field Risk Table, a tool used by planning teams to prioritize areas where manure should and should not be spread (NYS WRI, 1997). There are some indications that the Field Risk Table does not take into account existing knowledge about the production of nonpoint source pollutants in association with manure spreading. For instance, it does not include snow cover, even though manure application on top of or in snow would seem to be a significant problem because of increased pollutant transport during melt or rain-on-snow events and limited inactivation of oocysts not in contact with soil. In addition, the Field Risk Table only addresses flooding in a very general way, and it does not address effects of tile drains. Appropriate refinements should be made in future research conducted in support of the WAP.

2  

 Export immediately north or west would impact the upper Susquehanna, which forms the head-waters of the Chesapeake Bay watershed. Areas directly east are still within the New York City watersheds. Export south down the Delaware River Valley may be possible, but it is not known if there are agronomic needs for imported manure.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
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Conclusions and Recommendations for the Watershed Agricultural Program

Although agriculture is exempt from many provisions of the MOA, given its role as a pollution source and its predominance as a land use, the committee chose to examine the performance and principles involved in the WAP. Although this report does not assess whether the funds administered by the Watershed Agricultural Council are sufficient for accomplishing the intended outcomes, it is worth noting that the success of the WAP and related programs is directly related to the level and constancy of financial support.

  1. A scientifically based phosphorus load reduction goal that will achieve the desired phosphorus concentration in the water supply reservoirs should be developed. This process should take into account in-reservoir generation of phosphorus and phosphorus cycling and different forms of phosphorus. This load reduction can then be apportioned between the phosphorus outputs from individual subwatersheds.

  2. Additional farm-scale monitoring should be implemented to determine the ability of Whole Farm Plans to reduce nonpoint source pollution. Current analyses of Whole Farm Plans are limited to two sites within the watershed. NYC DEP and the WAP should establish additional demonstration farms for evaluating Whole Farm Plans and systems of BMPs. The monitoring program that would be necessary may be costly and will require the participation of additional scientists and technicians.

  3. Modeling and monitoring efforts should be better integrated. The WAP has access to multiple models with implications for management practices such as manure spreading and barnyard treatment. Additional models should be developed to take streambank protection BMPs into account. In relation to all models, more focused monitoring of individual BMPs is required to test and validate these models (for those BMP types that have not yet been tested). In particular, monitoring to determine the effectiveness of BMPs in removing pathogens (or microbial indicators) is greatly needed.

  4. Although the WAP has met the current milestones required for the FAD, these metrics do not establish the net impact of agriculture on water quality. The WAP, in conjunction with outside research teams, should determine appropriate monitoring and modeling tools available for the establishment of metrics that relate to actual water quality improvement.

  5. New York City must develop a greater understanding of factors controlling pathogen transport in the watersheds to determine the relative influence of agriculture as a source of pathogens as compared to other land

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

uses. The goal of such efforts should be to develop source terms for Giardia cysts and Cryptosporidium oocysts from various types of agricultural practices, especially calf-rearing. NYC DEP could benefit by assimilating work done on pathogen inactivation under variable environmental conditions and by making use of watershed models developed for nonpathogens (e.g., nutrients).

  1. The WAP and NYC DEP should continue to support science for the whole farm planning process. Funding gaps for this research has halted several relevant lines of work that could hold considerable benefits to the WAP. It is important that scientific findings continue to be integrated into the evolution of management plans.

  2. Lands enrolled in the Conservation Reserve Enhancement Program should be prioritized based (1) on frequency of inundation, (2) on vegetation type, and (3) on whether the landowner will voluntarily exclude livestock from riparian zones. If prioritization is not possible, rental and cost-share incentives should be increased to retire frequently flooded farmland into riparian forest buffers and to exclude livestock from streams.

  3. The WAP should conduct a comprehensive assessment of the relative merits and feasibility of manure storage versus manure export. All aspects of both scenarious should be considered. If it is determined that manure export is the only viable way to maintain agriculture in the watershed, the WAP should consider the implications of this for sustainability of animal-based agriculture within the Catskill/Delaware watershed.

  4. Implementation of Whole Farm Plans and long-term maintenance of best management practices must be addressed. Experience in other localities has shown that Whole Farm Plans are often not fully implemented, long-term maintenance of BMPs is difficult to achieve and, as a result, BMP effectiveness decreases with time (T. Dillaha, Virginia Polytechnic and State University, personal communication, 1999). Research and field experience has underscored the importance of active BMP maintenance in sustaining water quality. Program managers should consider what lessons could be learned from the maintenance of the Model Implementation Program (Box 9-1) when evaluating BMPs implemented under Whole Farm Plans. Program success will likely be greater if the WAC, NYC DEP, or some other appropriate watershed authority assumes responsibility for such maintenance.

WATERSHED FORESTRY PROGRAM

Forests are the most desirable land cover for the protection of water supply watersheds in temperate ecoregions. For this reason, when water supply water-

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

sheds are owned by the public or by a water utility, they are often converted to or maintained as forest preserve. In the New York City watersheds, much of the land area is privately owned (74 percent in the Catskill/Delaware region). In such areas as these, forestry (silviculture) is an important land use that can benefit both the private landowner and the water supply reservoirs.

Compared to other land uses, sustainable forest management leads to small-scale, infrequent, distributed environmental change while generating a wide array of goods and services. Therefore, it holds considerable promise for balancing resource use and watershed protection. However, in order for forestry to be the preferred land use in any region, common-sense principles must consistently guide management actions. Watershed managers for New York City, Boston, Providence, New Haven, Hartford, and scores of smaller communities and their rural neighbors throughout the Northeast are currently exploring the tradeoffs between active forest management, preservation, and other land uses.

The reckless disruption of forest ecosystems characteristic of late nineteenth and early twentieth centuries inspired the conservation movements in the United States and led directly to the establishment of the forestry profession in North America. Outdated images of massive clearcuts extending from ridgeline to ridgeline, forest fires roaring out of cutover3 into nearby towns, streams choked with sediment, and barren landscapes still influence the values and attitudes of an increasingly urban public. However, such scenes should not define what is possible, practical, and desirable for modern forestry. Box 9-2 lists commonly accepted principles of forestry sustainability; they are compatible with the goals and objectives of watershed management programs.

Program Description

The Watershed Forestry Program (WFP) was established in 1997 to improve the economic viability of forest land ownership and the forest products industry in ways compatible with water quality protection and sustainable forest management. Patterned after and affiliated with the Watershed Agricultural Program, the WFP was formed following the deliberations of a Watershed Forest Ad Hoc Task Force. The Task Force—comprised of foresters, local landowners, loggers, local and regional forest products industry representatives, representatives of nonprofit groups, and New York City and State officials—synthesized information about forests and forestry in the watershed region, identified problems and opportunities, and developed five overarching position statements for the WFP (Table 9-5).

The ideas, goals, and objectives set forth by the WFP correspond closely

3  

 Cutover is a term used in the late 1800s and early 1900s to describe large areas that were logged without regard for the condition of the site and other forest values, such as water quality, wildlife, recreation, and aesthetics.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
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BOX 9-2
Northern Forest Lands Council Principles of Sustainability

  • Maintenance of soil productivity.

  • Conservation of water quality, wetlands, and riparian zones.

  • Maintenance of a healthy balance of forest age classes.

  • Continuous flow of timber, pulpwood, and other forest products.

  • Improvement of the overall quality of the timber resource as a foundation for more value-added opportunities.

  • Addressing scenic quality by limiting adverse aesthetic impacts of forest harvesting.

  • Conservation and enhancement of habitats that support a full range of native flora and fauna.

  • Protection of unique or fragile areas.

  • Continuation of opportunities for traditional recreation.

Source: Northern Forest Lands Council (1994).

with other recent approaches, including the Massachusetts Metropolitan District Commission's management of the Quabbin Forest (Barten et al., 1998; MDC, 1995), the USDA Forest Service-sponsored Stewardship Incentive Program, and other contemporary examples (Bentley and Langbein, 1996; NRC, 1990, 1998). Although they are more comprehensive and sophisticated, most of the Task Force's findings and recommendations echo more general turn-of-the-century calls for conservation of forest resources. In fact, enabling legislation to acquire and manage U.S. national forests (now 220 million acres) was justified solely on the basis of watershed protection and restoration, not timber supply or wildlife conservation (Dana and Fairfax, 1980; Ellefson, 1992). Foresters and policymakers did, however, recognize the ecological and economic necessity of balancing water yield and quality, timber harvesting, wildlife populations, and recreational use.

Program Accomplishments

For a variety of reasons, the Catskills region has lagged behind many other areas of the Northeast and New England in the development and implementation of private lands programs. However, the WFP has served as a catalyst for changes

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
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TABLE 9-5 Position Statements of the Watershed Forestry Ad Hoc Task Force and Corresponding Policy Recommendationsa

Position Statements

Policy Recommendations

1. Well-managed forests provide the most beneficial land cover for water quality protection.

• Educate the public about the linkages between forests, forestry, water quality, and rural economies.

• Use conservation easements that allow for traditional uses and maintain undeveloped land.

2. Existing forest management activities are a negligible nonpoint source of pollution; however more extensive use of Best Management Practices (BMPs) will further reduce sediment and nutrient loading from forest management activities.

• Expand the logger training and certification program.

• Develop a user-friendly BMP field manual tailored to watershed conditions.

• Expand forest management outreach and plan development with landowners.

• Conduct a watershedwide, posttimber harvest survey to assess the effectiveness of New York State's timber-harvesting guidelines.

• Develop regulatory and economic incentives to improve BMP compliance and on-the-ground performance.

3. High property taxes discourage stewardship of private forest land.

• Reform New York State forest tax law (RPTL 480-a) to a current-use strategy equivalent to that of neighboring states with reimbursement to local governments.

• Develop alternative or supplemental funding sources for local governments and school districts (in addition to local property tax revenue).

• Establish a system of incentives to encourage owners of smaller parcels (<50 acres) to maintain their holdings.

4. Retention and growth of primary and secondary forest products manufacturing are essential to a healthy forest-based economy, forest land retention, natural resource protection, and sound forest conservation and management.

• Provide technical and financial assistance to forest landowners interested in long-term management to ensure a continuous supply of high-quality timber for local manufacturing.

• Foster an improved business climate to develop and sustain local forest-based industry.

• Promote the inclusion of forestry and the forest products industry in economic development studies.

5. Existing public forest lands should provide a model for sound resource management that complements private stewardship.

• NYS DEC and NYC DEP forest lands should, where appropriate, serve as examples of sustainable forest management.

a Position statements are direct quotations from the original source while policy recommendations are paraphrased.

Source: WFAHTF (1996).

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

in the practice of forestry and in long-term prospects of forest landowners in the region. Now it is frequently cited as a model for other areas of the United States (Jannik, 1998).

Although the WFP is new, progress toward objectives has been rapid and substantial. Work on most policy recommendations is now under way. Several BMP (focused on sediment control) and logger training workshops have been held in the region, and temporary bridges for stream crossings are available as a no-cost loan to area loggers (Kittredge and Woodall, 1997; Kittredge et al., 1997). A pilot project using geotextiles to stabilize forest roads in sensitive areas is under way. Postharvest field assessment of BMP effectiveness by independent scientists is in progress on more than 60 sites throughout the Catskill and Delaware watersheds.

Thirty-four (34) professional foresters have qualified as "approved contractors" to prepare and implement forest management plans on private lands. Administrative procedures for forest management plan specifications, cost sharing, and NYS DEC review have been developed and are being implemented. To date, 78 landowners and a combined area of 21,000 acres have been enrolled in the program. Figure 9-2 shows that the model forest demonstration sites and forest management plans are evenly distributed across the Catskill/Delaware watershed.

Education and outreach efforts have included (1) watershed forest tours for members of New York City-based environmental groups, (2) informational meetings with members of local, New York City, and State governments, and (3) active collaboration with NYC DEP and NYS DEC foresters. In addition, the WFP has established four demonstration forests with the assistance of the New York State College of Environmental Science and Forestry, local scientists and foresters, and the USDA Forest Service.

Enhancement of local and regional markets for wood products is under way. Forest land owners and loggers who are harvesting low-value species (e.g., red maple and beech) and low-quality oak logs during thinning and stand-improvement operations are being connected with pallet lumber and fuelwood buyers in the New York City metropolitan area. For high-value species and logs (oak, white pine, black cherry, sugar maple, yellow birch), connections are being made with local and regional mills and manufacturing facilities. A recent study of the community and economic benefits of the Massachusetts MDC Forestry program on the 55,000-acre Quabbin Reservoir watershed indicates what is possible for the WFP (NWF, 1998). At least 110 jobs in local communities, with a total annual payroll of $4 million, are directly related to the wood harvested from the Quabbin forest. In 1995, for example, the MDC forest management added an estimated total of $34 million to the state's economy and supported 290 jobs. Between 1992 and 1996, the Quabbin forest produced 20 million board-ft of sawtimber, 16,000 cords of fuelwood, and 22,500 tons of pulpwood from an area of approximately 40,000 acres, with a total estimated economic benefit of $120 million.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

FIGURE 9-2 Watershed Forestry Program activities as of December 1998. Source: NYC DEP (1999b).

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

Program Analysis

Absolute measures of program performance are not available because of the young age of the WFP. It is anticipated that monitoring criteria and tools for forestry BMPs will be the most significant future need. As such, principles for developing and monitoring forestry BMPs are discussed below. In addition, important economic and ecological considerations for the sustainability of forestry in the Catskills are discussed.

Forestry BMPs

The basic principles guiding the design and implementation of forestry BMPs center on key hydrologic processes and ecosystem attributes, with the primary aim of preventing negative impacts. These principles include the following:

  • Full integration of soil and water conservation into planning and operations.

  • Protection of the litter layer and soil surface.

  • Avoidance or dissipation of overland flow.

  • Avoidance of hydrologic connections to wetlands, streams, and lakes.

  • Adjustment of forest operations to weather and terrain.

  • Combining of biological and physical controls.

These principles and practices proactively avoid or treat causes rather than reacting only to symptoms or unacceptable conditions. The reasons for many practices are self-evident (e.g., avoiding soil compaction, erosion, and sediment transport), yet only rarely are they assembled and implemented as a system.

A system of BMPs should encompass the full operational cycle of forest management activities from planning, developing access, and harvesting to renewal and restoration (Table 9-6). In recognition of their potential impact, most BMPs focus on roads, road-stream crossings, and skidding operations to minimize adverse long-term impacts and on riparian buffers and forest regeneration to ameliorate short-term changes.

Although a complete list of forestry BMPs being used in the Catskill/Delaware watershed is not yet available (the WAC is developing such a manual to be released in 1999), guidelines for forestry BMPs have been published by NYS DEC. Its catalogue of silvicultural management practices (NYS DEC, 1993) includes planned harvest operations, riparian buffer protection, planned watercourse crossings, planned access routes, sediment barriers, vegetation establishment, and hazardous materials management. These guidelines, developed by a multiorganization task force, correspond closely with the system outlined in Table 9-6. The addition of on-the-ground performance evaluations (monitoring and research) would be appropriate and necessary in public water supply watersheds.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

TABLE 9-6 System of Forestry Best Management Practices

Nonstructural Measures

Planning, site reconnaissance, scheduling, walking the road centerline and harvest units, contracts (performance standards and bonds), field supervision

Road Design, Construction, and Maintenance

Placement and alignment, minimizing grades and width. stabilization and restoration, scheduled inspection and maintenance

Stream and Wetland Crossings

Hydraulic structures, approach, and stabilization measures designed to protect road, stream channel, wetlands, and aquatic resources

Landings

Minimal size, distributed drainage, woody debris returned to adjacent forest, controlled equipment maintenance and fueling

Skid Trails

Equipment specifications consider ground pressure and total weight, skidder bridges or brush mats to cross fragile or wet areas, bumper trees to protect residual stand

Felling Operations

Marking (to guide or limit equipment access), operator training and supervision, directional felling and pre-bunching

Riparian Buffers

Zone 1 – shade, cover, food web functions, and bank stability

 

Zone 2 – nonpoint source pollutant assimilation

 

Zone 3 – stormflow control (as needed)

Site Stabilization and Restoration

Restore secondary roads, limit access in cooperation with landowners and local communities

Monitoring and Research

To verify the effectiveness of BMPs, improve operational procedures, develop better techniques, reduce scientific uncertainty

 

Source: Reprinted, with permission, from Barten, 1998.

Nonindustrial Private Forest Owners

People buy forest land for many reasons: privacy, recreational opportunities, a convenient and reliable source of fuelwood, periodic revenue from timber harvesting, direct use of lumber (after processing at a local sawmill or with a portable mill) for construction or woodworking, or some combination of the above (Leak et al., 1997; NRC, 1998; Rickenbach et al., 1998). Turnover or subdivision of smaller parcels (<50 acres), often occurring every 5–15 years, can be the bane of long-term forest and watershed management programs. Because trees grow slowly, this is usually not enough time for the multiple benefits of forest stewardship to accrue. The WFP and similar initiatives around the United States are designed to counteract frequent turnover and substandard management to ensure source water protection.

Forest Land Ownership and Taxation

A major impediment to the sustainability of forestry in the Catskill/Delaware region is the imbalance between taxes and expected forestry revenues. Through-

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

out the United States, the most frequently cited reason for sale or subdivision is property tax burden (NRC, 1998). In the Catskill region, average annual property taxes on private forest lands are about $14 per acre while average annual revenue from forest product sales (fuelwood and sawtimber) is about $6 per acre (WFAHTF, 1996). Short-term financial pressures obviously discourage long-term investments in silvicultural techniques to improve the value and condition of the forest, such as stand improvement, low-intensity thinning, or uneven-aged management (Davis and Johnson, 1987; Smith et al., 1997).

The USDA Forest Service Stewardship Incentive Program, local conservation easements and current-use tax assessments, and education and outreach are expressly designed to counteract financial pressures and land turnover. They are having a positive effect in most eastern states (Campbell and Kittredge, 1996; Jannik, 1998; NRC, 1998). Conservation easements on forest land in the Catskill/Delaware watershed are likely to become more common because the area has been declared part of the Forest Legacy Program of the USDA Forest Service (NYC DEP, 1999b). In the absence of these types of programs, the gap between forestry expenses and revenues widens. This compels some landowners to cut only high-value trees such as black cherry, northern red oak, yellow birch, and sugar maple simply to maintain ownership of the larger parcel. In the worst case, when high-value trees are continually removed (''high-grading"), biological diversity, tree health, and vigor are steadily reduced. Resistance and resilience to insects, diseases, and natural disturbances such as severe storms, as well as the ameliorative effect of forests in headwater areas, are gradually diminished.

Forest Health

In addition to economic pressures and land tenure issues, the ecological legacy of exploitative logging during the 1800s (clearcutting hemlock for tanbark and subsequent hardwood regeneration for charcoal and fuelwood) described in an earlier chapter is a degraded, predominantly even-aged forest. Exotic insects like gypsy moth can seriously damage oak stands. A woolly adelgid, accidentally introduced from Japan, threatens the few remnant stands of eastern hemlock. Dutch elm disease and chestnut blight have virtually eliminated their host tree species from northeastern forests. More recently, atmospheric deposition has caused widespread mortality of high-elevation red spruce and balsam fir (Lovett et al., 1998; Lovett and Lindberg, 1993; Lovett and Kinsman, 1990). In sum, there are substantial economic and ecological challenges that highlight the need for forest conservation and stewardship in the Catskills region.

Conclusions and Recommendations for the Watershed Forestry Program

  1. The Watershed Forestry Program should continue its comprehensive efforts to promote sustainable forest management in the region. Outreach,

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

training, monitoring, and research efforts are self-reinforcing when they are advanced as a balanced program. As with the WAP, success in the WFP will depend largely on the active implementation and maintenance of forestry BMPs over the long term.

  1. A spatially referenced database of forest lands, owners, management objectives, and activities should be developed to track on-the-ground progress and performance of forestry practices. The Geographic Information System (GIS) should be used to spatially link (1) databases with landowner information, forest resources inventory (at the stand level), management objectives, and silvicultural prescriptions and treatments, (2) watershed characteristics (e.g., topography, soils), and (3) current and future subwatershed conditions. Its use would enable watershed managers to evaluate changes (positive, negative, or non-detectable) in the quantity, quality, and timing of streamflow as influenced by the WFP and other land or resource uses.

  2. Water quality monitoring should be implemented on the model forests and in conjunction with NYC DEP and NYS DEC networks on other tributaries. The WFP is encouraged to merge landowner, management plan, and field assessment data with water quality data to evaluate program performance. It is likely that reference watersheds could be used for WFP and WAP monitoring. The GIS/forest management database suggested above (recommendation 2) would provide data and information about WFP activities upstream of NYC DEP and NYS DEP monitoring stations. When coupled with a paired watershed and/or "above and below" sampling, valuable data and information about the cumulative impact (positive or negative) of the WFP and WAP would be available.

  3. The Watershed Forestry Program should foster the movement toward third-party green certification of forest management (Forsyth et al., 1999; Hayward and Vertinsky, 1999; Mater et al., 1999). The Vermont Family Forests landowner cooperative is an excellent prototype for the Catskill/Delaware region. Resource manager and public land certification in New York, Pennsylvania, Massachusetts, and other New England states can serve as a model for consulting foresters.

  4. It is recommended that New York State consider tax policy changes that would promote sustained management of private forest land including forests on relatively small parcels that are suitable for development. Because of the benefits of such programs extend beyond the local political boundaries, impacts on town revenues should be evaluated, and mitigation payments to local governments by the State should be made as an integral part of the program.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

STORMWATER POLLUTION PREVENTION PLANS

Urban stormwater is the final type of NPS pollution considered in this chapter. Most types of new, large-scale development in the New York City watershed region are required to submit a Stormwater Pollution Prevention Plan (SPPP) for controlling the quantity and quality of stormwater runoff generated by new impervious cover (MOA, Appendix X, Section 18-39). SPPPs specify best management practices that will prevent erosion and sedimentation during construction and any increase in the rate of pollutant loading in stormwater after construction. These plans must include a quantitative analysis demonstrating that runoff quantity and quality from postconstruction conditions will be less than or equal to that of preconstruction conditions. Whether or not an SPPP or some other type of stormwater plan is developed depends on a number of factors, including the proximity of the project to nearby waterbodies. For detailed information on the multiple types of stormwater plans and the activities that require them, see NYC DEP, 1997b.

Although they have existed since 1993 as part of the NYS DEC's General Permit for stormwater discharges, SPPPs have recently received considerable attention because of their inclusion in the MOA for a variety of activities. Prior to the MOA, fewer activities required the drafting of an SPPP, and the regulatory oversight was spread among multiple agencies. It is not surprising, then, that SPPPs have spawned a great deal of confusion among engineers, developers, and local and State agencies about how SPPPs should be interpreted and implemented, since most of these organizations had no prior experience with stormwater quality control and/or stormwater BMP design.

Stormwater Pollution Prevention Plan Contents

An SPPP must include a description of the proposed construction activities. An estimate of pre-and postdevelopment runoff is required, considering both the quantity and quality of stormwater. Pollutants of concern vary, but often include biological oxygen demand, phosphorus, nitrogen, total suspended solids, organic matter, and bacteria. Measures that might be undertaken to reduce runoff rates and pollutant loading from stormwater are then presented. These measures are committed to a Stormwater Management Plan, which describes the specific BMPs that will be used to ensure that the postdevelopment runoff rates will not exceed predevelopment runoff rates for the 2-year, 10-year, and 100-year 24-hour storms. To prevent pollutant loadings, the Stormwater Management Plan must control the "first flush"—the first half inch of runoff from the 1-year, 24-hour storm event. However, there are no numeric standards requiring a certain amount of pollution to be removed by stormwater BMPs. Erosion and Sediment Control Plans are also part of an SPPP. These contain a complete description of the BMPs that will be used to control erosion during each phase of construction. The methods,

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

criteria, and documentation for preparing an SPPP are contained in a series of guidance and permit documents (NYC DEP, 1997b; NYS DEC, 1996).

Performance of Stormwater BMPs

Throughout the SPPP guidance document, it is clear that the goal is to prevent postdevelopment loadings of pollutants from exceeding predevelopment levels (NYC DEP, 1997b). The requirement is stated by the following: "Regulations require that pre- and postconstruction runoff characteristics not be substantially altered." In order for this to be achieved, the SPPPs rely on an underlying premise that current engineering technologies (i.e., stormwater BMPs) are capable of reducing postdevelopment pollutant loadings to predevelopment levels. Unfortunately, there is little basis for confidence that the current generation of urban stormwater BMPs can reduce pollutant loads to levels that approach predevelopment conditions. Table 9-7 provides a summary of reported nutrient removal rates for stormwater BMPs.

Phosphorus Removal

Although their removal rates are variable, most BMP groups have median annual removal rates in the 30 percent to 50 percent range for both soluble and total phosphorus (Table 9-7). Dry extended detention ponds and open channels

TABLE 9-7 Median Removal Rates for Selected Groups of Stormwater Practices

BMP Groups

Median Removal Rate, %

n

TSS

Total P

Sol P

Total N

Nitrate

Carbon

Wet Ponds

36

67

48

52

31

24

41

Stormwater Wetlands

35

78

51

39

21

67

28

Sand Filtersa

11

87

51

-31

44

(-13)

66

Channels

9

0

(-14)

(-15)

0

2

18

Water Quality Swalesb

9

81

29

34

ND

38

67

Notes: n is a number of performance monitoring studies. The actual number for a given parameter is likely to be slightly less. Sol P is soluble phosphorus, measured as orthophosphate, soluble reactive phosphorus, or biologically available phosphorus. Carbon is a measure of organic carbon (BOD, COD, or TOC). ND = not determined.

a Excluding vertical sand filters and vegetated filter strips, but including organic filters.

b Includes biofilters, wet swales and dry swales.

Source: Brown and Schueler (1997). Reprinted, with permission, from Center for Watershed Protection, 1997. ©1997 by Center for Watershed Protection.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

showed low or no ability to remove either total or dissolved phosphorus. Interestingly, several BMP groups—wetlands, water quality swales, and sand filters—exhibit very wide variation in phosphorus removal, suggesting internal nutrient cycling can be an important factor in determining BMP effectiveness. Some BMPs, such as sand filters, actually increase soluble phosphorus concentrations via desorption, dissolution, or extraction of phosphorus into the aqueous phase.

These removal rates are average annual load reductions, and the removal rates do not account for diminished removal related to poor design or construction, age, or lack of maintenance. It is also important to remember that trapping of phosphorus within a stormwater BMP is only a temporary form of removal; ultimate removal is dependent on the cleanout, removal, and safe disposal of trapped sediments through periodic maintenance. For stormwater wetlands, continued phosphorus removal may require periodic replacement of wetland media as adsorption sites diminish over time (Oberts, 1997).

The moderate phosphorus removal of stormwater BMPs needs to be balanced against the sharp rise in phosphorus loads produced by new development. The effect of stormwater BMPs on phosphorus load as a function of impervious cover is shown in Figure 9-3. At a low density of development (5 percent to 25 percent site impervious cover), the reduction in phosphorus load by stormwater BMPs keeps pace with the increased load produced by impervious cover. After that point, however, stormwater BMPs can no longer achieve predevelopment phosphorus loads.

Bacterial Removal

To date, studies evaluating the performance of stormwater BMPs in removing microbial pathogens have focused on bacteria. Urban stormwater BMPs must be extremely efficient if they are to produce stormwater effluents that meet the 200-CFU/100 mL standard for fecal coliforms at a site. Assuming a national mean storm inflow fecal coliform concentration of 15,000/100 mL (see Table 5-6), a 99 percent removal rate is needed to meet the standard. The limited research conducted to date indicates that current BMPs cannot meet this standard on a reliable basis. Only 24 BMP performance-monitoring studies have measured the input and output of fecal coliform bacteria from stormwater BMPs during storm events. These data, collected for fecal coliform, fecal streptococcus, and E. coli, are summarized in Table 9-8.

For stormwater ponds, the mean fecal coliform removal efficiency was about 65 percent (range was from –5 percent to 99 percent). The mean removal efficiency calculated for sand filters was lower (about 50 percent), but these practices had a wider range in reported removal (–68 percent to 97 percent). It should be noted that most sand filter performance data have been collected in warm seasons, and most sites were in Texas—conditions unlike those in the Catskill/Delaware watershed. Grass swales and biofilters were found to have no ability to

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

FIGURE 9-3 Relationships between impervious cover, phosphorus loads, and stormwater BMP performance in a typical watershed. The grey band indicates typical "background" phosphorus loads from undeveloped watersheds. The BMP-Hi line illustrates the effect of reducing phosphorus loads using BMPs with an average long-term removal rate of 60 percent. The BMP-Lo indicates a 40 percent removal rate. It should be noted that actual curves in individual watersheds may be different. For example, the contribution of new septic systems that accompany development to overall phosphorus loading is not represented by these curves. Source: Schueler (1996). Reprinted, with permission, from Center for Watershed Protection, 1996. © 1996 by Center for Watershed Protection.

TABLE 9-8 Comparison of Mean Bacterial Removal Rates Achieved by Different Stormwater BMP Groups

Bacterial Indicator

Bacterial Removal Rate, %

Ponds

Sand Filters

Swales

Fecal Coliform

65% (n =9)

51% (n=9)

–58% (n=5)

Fecal Streptococci

73% (n =4)

58% (n=7)

ND

E. coli

51% (n=2)

ND

ND

ND=not determined

Source: Schueler (1999). Reprinted, with permission, from Center for Watershed Protection, 1999. © 1999 by Center for Watershed Protection.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

removal fecal coliform bacteria, with zero or negative removal reported in four of the five studies. Pet wastes and in situ multiplication of bacteria were cited as the primary reason for the poor performance. No performance monitoring data are available to assess the capability of infiltration or wetland BMPs to remove coliforms. The limited data on fecal streptococcus and E. coli removal by stormwater BMPs are generally comparable to the more abundant fecal coliform data, suggesting that fecal coliform is a sufficient indicator of these organisms. There are no current monitoring data on Giardia, Cryptosporidium, or Salmonella removal by stormwater BMPs. Based on the mediocre effectiveness of BMP removal mechanisms for fecal coliforms, and the survivability of cysts and oocysts in sediments, the committee expects that it will be difficult to reliably remove the protozoan pathogens from urban runoff using traditional stormwater BMPs.

In summary, current BMP technology is not capable of removing fecal coliform bacteria to meet the 200-CFU/100 mL standard in stormwater discharges, assuming a national average bacterial concentration in stormwater influent. If no net increase in bacterial concentrations in postdevelopment runoff is desired, it may be necessary to install stormwater BMPs at both current development projects as well as at older, neighboring development sites. As written, the SPPPs call for a level of BMP performance that simply cannot be met with current stormwater techniques at most highly developed sites. As discussed in detail in Chapter 8, the use of multiple BMPs in series at individual sites cannot reduce postdevelopment loadings below predevelopment levels.

Acreage Requirements for Stormwater Quality Controls

With some exceptions, the Watershed Rules and Regulations exempt development projects of less than five acres in size from the stormwater pollution prevention plan requirements4. Many kinds of small-scale industrial and commercial development are thus allowed to produce phosphorus and bacteria loads without treatment. Most states and localities that currently regulate stormwater discharges have a much lower threshold for stormwater requirements (usually less than one acre) (Watershed Management Institute, 1997). Although it is true that even very low-acreage thresholds (30,000 ft2) have been found to allow as much as 25 percent of stormwater to pass through untreated (Booth and Jackson, 1997), the efficacy of stormwater management will be markedly improved by lowering the current threshold from five acres to one acre. A one-acre threshold

4  

 SPPPs are also required, regardless of acreage, for construction of a subdivision; construction of an industrial, commercial, multifamily, or municipal project where more than 40,000 sq. ft. of impervious surface will be created; a landclearing or grading project involving two or more acres that are partially located on slopes greater than 15 percent or within setback distances from waterbodies; construction of an impervious surface in a village, hamlet, village extension, or area zoned for commercial or industrial uses West-of-Hudson; or construction of an impervious surface within a East-of-Hudson designated Main Street area.

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

should be the basis for further refinement, using the GIS database to identify the most appropriate long-term threshold given land development patterns in the watershed.

Sizing Criteria for Designing Stormwater BMPs

The SPPPs contain three different sizing criteria that must be considered when designing stormwater treatment facilities. The chosen BMPs must treat the greater of (1) the first half inch of runoff from impervious areas of the site or (2) the runoff produced by the one-year, 24-hour storm event (approximately 2.5–3.0 inches of rainfall). In phosphorus- and coliform-restricted basins, the BMPs must treat the runoff produced by the two-year, 24-hour storm event (approximately 3–4 inches of rainfall). The latter two sizing criteria are among the largest sizing criteria for stormwater runoff in the United States. The regulations, however, provide no guidance for designing BMPs that can fulfill these requirements, either in terms of the hydrologic models that should be employed or standardized parameters. Consequently, design engineers and state and local regulatory agencies are in frequent conflict as to how SPPPs should be interpreted and applied. The derivation of more effective sizing criteria should become a high priority for NYC DEP.

It should be noted that the larger stormwater treatment volumes do not necessarily lead to proportionately greater levels of pollutant removal. For example, a BMP designed to capture runoff from the one-year storm is able to treat 90 percent of the annual stormwater runoff volume each year (MDE, 1999). A BMP designed to capture runoff from the two-year storm is able to treat only 95 percent to 97 percent of the annual runoff volume produced each year, even though it is four times larger in size (and cost). BMP research has shown that treatment volume alone is not a reliable predictor of pollutant removal performance. Other design variables, such as internal geometry, pretreatment, conveyance, and multiple treatment pathways, are very important in determining pollutant removal. Yet the SPPP requirements offer minimal guidance on these other important design parameters. The lack of a stormwater design and engineering manual and of performance criteria for individual BMPs for the New York City watersheds is a major impediment to achieving higher and more consistent pollutant removal. Other states such as Maryland have recently produced detailed and useful manuals to assist engineers in designing and building more effective BMPs (MDE, 1999).

Need for Program Support

The Watershed Rules and Regulations of the MOA have introduced stormwater control technologies into a region of the country that had little or no prior experience with stormwater management. The regulations emphasize a

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

permit-driven approach rather than a performance-based approach. That is, an SPPP relies strongly on quantitative (and highly theoretical) calculations, rather than on performance monitoring or strict requirements for BMP size and treatment efficiency. The SPPP program does not currently have the basic support needed to foster success in the areas of training, engineering manuals, performance monitoring, review staffing, program financing and demonstration projects, maintenance requirements, design methods, BMP feasibility guidance, construction and maintenance inspection criteria, or BMP specifications. As the Watershed Management Institute (1997) notes, strong program support in these areas has been the critical ingredient in effective implementation of stormwater requirements in other localities. It will be critical to the success of stormwater management in the New York City watersheds as well.

Incentives to Reduce Impervious Cover

The SPPP approach relies heavily on the use of structural stormwater practices such as ponds, wetlands, filters, and infiltration. Although these practices are an essential component of an effective stormwater quality strategy, they need to be combined with site design practices that reduce the amount or impact of impervious cover created by land development. Better site design techniques (narrower streets, open-space subdivisions, smaller parking lots, and on-lot bioretention) are being advocated by many stormwater agencies (Arendt, 1997; BASMAA, 1997; CWP, 1998; MDE, 1999). Recent modeling work has indicated that widespread application of better site design techniques can provide stormwater pollutant reduction equivalent to that achieved by structural stormwater practices (Caraco et al., 1998). When better site design techniques and structural practices are combined, nutrient loadings are projected to decline to levels 30 percent to 50 percent lower than what can be achieved using conventional subdivision designs.

The Watershed Rules and Regulations and the SPPP requirements provide no incentives for developments that employ better site design techniques. Recently, the state of Maryland provided a series of stormwater quality credits for developments that use better site design (MDE, 1999). These credits could be adapted for developments in the New York City watersheds.

Conclusions and Recommendations

  1. For phosphorus, current stormwater best management practices are only moderately effective. In almost all cases, they cannot reduce postdevelopment loadings to predevelopment levels.

    Most current practices show some ability to remove bacteria but not enough to meet current water quality standards. Swales are capable of no net

Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
×

removal. Because urban areas are a source of Cryptosporidium oocysts (see Chapter 5), this deficiency is particularly notable.

  1. Stormwater Pollution Prevention Plans should be required for activities greater than one acre, rather than for those greater than five acres. The five-acre measure was likely derived from the fact that activities that affect less than five acres are generally not required to obtain an NPDES permit for stormwater. However, most communities have recognized that one acre is a more appropriate lower limit. Lowering the size requirement is important because much of the new development in the Catskill/Delaware watershed may be on a small scale.

  2. NYC DEP should develop guidance material for designing stormwater BMPs that can meet the one-year, 24-hour storm event and the two-year, 24-hour storm event.

  3. NYC DEP should embrace a performance-based approach to stormwater management rather than the permit-based approach embodied by the current SPPPs. Among other things, guidance material for such a new approach should include information on performance monitoring of stormwater BMPs for a variety of pollutants, including Cryptosporidium, and on long-term maintenance of stormwater BMPs.

  4. The Stormwater Pollution Prevention Plans should encourage the use of nonstructural BMPs that limit the amount and the adverse effects of impervious surfaces. Excellent examples of good site design practices using such BMPs are found in Maryland.

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Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
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Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
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Suggested Citation:"9 Nonpoint Source Pollution Management Practices." National Research Council. 2000. Watershed Management for Potable Water Supply: Assessing the New York City Strategy. Washington, DC: The National Academies Press. doi: 10.17226/9677.
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In 1997, New York City adopted a mammoth watershed agreement to protect its drinking water and avoid filtration of its large upstate surface water supply. Shortly thereafter, the NRC began an analysis of the agreement's scientific validity.

The resulting book finds New York City's watershed agreement to be a good template for proactive watershed management that, if properly implemented, will maintain high water quality. However, it cautions that the agreement is not a guarantee of permanent filtration avoidance because of changing regulations, uncertainties regarding pollution sources, advances in treatment technologies, and natural variations in watershed conditions.

The book recommends that New York City place its highest priority on pathogenic microorganisms in the watershed and direct its resources toward improving methods for detecting pathogens, understanding pathogen transport and fate, and demonstrating that best management practices will remove pathogens. Other recommendations, which are broadly applicable to surface water supplies across the country, target buffer zones, stormwater management, water quality monitoring, and effluent trading.

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