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1 Introduction T he Chesapeake Bay is North America’s largest and most biologically diverse estuary, home to thousands of species of plants and animals (CBP, 2000) as well as an important commercial and recreational resource. The Chesapeake Bay serves as a key economic driver in the mid- Atlantic region, and the Chesapeake Bay Foundation (2010) valued its worth at over one trillion dollars to the watershed’s economy. The Bay’s ecosystem has been affected by human influences since early settlements, but these influences became known and more pronounced during the 20th century. Today, almost 17 million people live within the Bay’s 64,000 square mile (166,000 square kilometer) watershed in six states—Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia—as well as the District of Columbia (Figure 1-1; CBP, 2010a). Excess amounts of nitrogen, phosphorus, and sediment from human activities and land development, including agriculture, urban and suburban runoff, wastewa- ter discharge, and air pollution, are sent to the Bay (CBP, 2010a). These pollutants and other chemical and physical alterations have disrupted the ecosystem, causing degraded habitats and harmful algal blooms that impact the survival of fish, shellfish, and other aquatic life. The Chesapeake Bay was among the first of the major U.S. estuaries where concerted efforts were made to understand the causes and conse- quences of changing ecosystem conditions. During the mid-1970s, a young U.S. Environmental Protection Agency (EPA) led the first comprehensive and detailed attempt to understand the Bay’s condition and what would be necessary to restore it to its former condition. That 7-year research effort culminated in the report, Chesapeake Bay: A Framework for Action (EPA, 13
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14 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY FIGURE 1-1 Chesapeake Bay Watershed. SOURCE: CBP (2008). Available at http://www.chesapeakebay.net/maps. aspx?menuitem=16825. Figure 1-1 AND S-1.eps bitmap 1983a,b), which described the condition of the Bay’s ecosystem, its change over time, and scientific evaluations of the Bay’s functions in relation to its condition. The report established a framework for action to address some of the Bay’s most significant problems. Expert panels assembled by the EPA recommended immediate attention to the cultural eutrophication caused
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15 INTRODUCTION by nutrient enrichment, which had caused a long-term decline in the Bay’s health (EPA, 1983a,b). In 1983, the Chesapeake Bay Program (CBP) was established, based on a cooperative partnership among the EPA, the state of Maryland, the com- monwealths of Pennsylvania and Virginia, and the District of Columbia, to address the extent, complexity, and sources of pollutants entering the Bay (EPA, 1983a). By 2002, the states of Delaware, New York, and West Virginia committed to the CBP’s water quality goals by signing a Memo- randum of Understanding (CBP, 2002). A key component of the restoration program focuses on improving the water quality in the Bay and its tidal tributaries. Water quality is evalu- ated according to three parameters that are linked to one or more of the Bay’s habitats and faunal communities: dissolved oxygen, water clarity, and chlorophyll a. Criteria for these three water quality parameters serve as the basis for the current goals, spurring efforts to reduce nutrient and sediment loads. Excess nitrogen and phosphorus loads fuel the growth of algal blooms, which increase chlorophyll concentrations, reduce clarity, and contribute to hypoxia (or low dissolved oxygen levels). Hypoxia, in turn, impacts water quality and habitat, especially underwater grasses and associated aquatic life (reviewed in NRC, 2000). In addition to these direct responses to nutrient enrichment, indirect responses and nonlinear feed- back mechanisms, such as increased turbidity associated with the decline of filter-feeding bivalves and underwater grasses, may play an important role in the Bay’s degradation (Kemp et al., 2005). Other stressors such as chemical contaminants from air pollution, climate change, habitat destruc- tion, and over-harvesting of fish and shellfish also stress the Bay and its living resources at great environmental, economic, and social costs to the populations that rely on a healthy ecosystem (CBP, 2010a). In this introductory chapter, the sources and impacts of nitrogen, phos- phorus, and sediment pollution in the Bay watershed are reviewed. A brief history of the CBP’s efforts is presented to provide context for the major current initiatives, including the total maximum daily load (TMDL) and the two-year milestone strategy. Finally, the committee’s task and approach are discussed. NITROGEN, PHOSPHORUS, AND SEDIMENT IN THE CHESAPEAKE BAY WATERSHED Since colonization by Europeans almost 400 years ago, the Chesa- peake Bay and its watershed have undergone significant human-induced changes, such as deforestation and urban development. The watershed is still dominated by wooded and open space (69 percent of the watershed), but agricultural and developed land uses (22 and 7 percent, respectively) are
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16 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY significant and increasing (EPA, 2010a). Sedimentation from agricultural expansion and land-use conversions, runoff of fertilizers and animal wastes, and atmospheric deposition of nitrogen from fossil fuel combustion and agriculture have contributed to observed changes to the Bay (Brush, 2009; Cooper and Brush, 1991). By the mid-1980s, the Bay was receiving 7 times more nitrogen and 16 times more phosphorus than when English colonists arrived (Boynton et al., 1995). This section briefly describes the specific sources of nitrogen, phospho- rus, and sediments to the Bay and its watershed. These sources are internal (e.g., biological processes in soils, sediments, and the water column) and external (e.g., commodity imports, atmospheric deposition). On the whole for the Bay and its watershed, anthropogenic sources of both phosphorus and nitrogen are several-fold larger than natural sources (Boynton et al., 1995; reviewed in Rabalais et al., 2009). Annual loads of nutrients and sediment vary widely with climatic conditions, with wet years leading to much higher loads (see Figure 1-2). Because this variability can create challenges for calculating source contri- butions, the pollutant source data presented in this section are largely based on model output. The data were produced by the CBP Phase 4.3 Watershed Model or the CBP Airshed Model (Box 1-1) and were presented in the Bay Barometer (CBP, 2010a). Recent watershed model updates provided new estimates, but the committee was unable to disassociate Phase 5.3 Water- shed Model source load data to account for the specific contributions of atmospheric sources.1 The Phase 4.3 Watershed Model data presented in this section represent loading averages based on simulations over 14 years of hydrologic record using land use, best management practices (BMPs), and point-source controls reflecting 2007 conditions. Nitrogen Imported fertilizer and commodities (e.g., grain), primarily from other regions in the United States, and atmospheric deposition are important external sources of nitrogen to the Bay watershed. Atmospheric deposition of oxidized reactive nitrogen (NOy; the sum of nitric oxide [NO] and nitro- gen dioxide [NO2] [collectively termed NOx] + all other oxidized nitrogen 1 In many CBP reports, atmospheric deposition is frequently lumped into the source sector on which the nitrogen is deposited (i.e., nitrogen deposition on forested lands is considered a forest source). Thus, atmospheric deposition is reported as a much smaller fraction than the plots included in this chapter (e.g., Figure 1-3), which consider the original sources of the nutrients. Plots showing the actual sources were not available from the CBP Watershed Model Phase 5.3; therefore, these source data reflect model output from the earlier model, Phase 4.3. Comparison data to the latest model version are provided in subsequent footnotes.
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17 INTRODUCTION Figure 1-2.eps FIGURE 1-2 Nitrogen and phosphorus loading (millions of pounds) delivered to bitmap the Chesapeake Bay and total river flow (billions of gallons), 1990-2009. These loading estimates are based on direct measurements (i.e., monitoring in tributary rivers and point source discharges) supplemented by model estimates for ungaged portions of the watershed. The red lines indicate the 10-year average load targets for nitrogen and phosphorus (175 million pounds and 12.8 million pounds, respec- tively) established in EPA (2003). SOURCE: CBP (2010a).
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18 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY BOX 1-1 Chesapeake Bay Models The CBP relies upon models to forecast the effects of changing nitrogen, phosphorus, and sediment management in the Chesapeake Bay. The models also form the basis of the current total maximum daily load (TMDL) allocations. The models are of two types: (1) models that simulate the physical, chemical, and biological processes in the airshed (Chesapeake Bay Airshed Model), watershed (Chesapeake Bay Water- shed Model), and estuary (Chesapeake Bay Water Quality and Sediment Transport Model [or Bay Model]) and (2) models that convert land-use practices and implementation of best management practices (BMPs) into predictions of nutrient and sediment loads under average hydrologic conditions (the Land Use Change Model and Scenario Builder). The Bay Airshed Model combines a wet deposition regression model with a continental-scale air quality model called the Community Multi- scale Air Quality (CMAQ) Model. The Airshed Model provides the quan- tity of nutrients deposited via rainfall and dry deposition to the watershed and the Bay’s surface. The Watershed Model is based on the Hydrologic Simulation Program- Fortran (HSPF) model. It receives the atmospheric and other nutrient in- puts and stimulates the quantity of nutrients and sediment discharged to the tributaries and main stem Bay. It is a lumped-parameter model, which means that it is not able to represent spatial locations of specific land use categories in each of the many small watersheds in the overall Chesa- peake Bay basin. Further, HSPF does not mathematically characterize the time dependency (lag) of the farm plot scale response to agricultural BMPs, nor does it consider lag times introduced by groundwater flow. In other words, an assumption in the HSPF model is that nutrient reduc- tions due to BMP implementation are instantaneous load reductions as a simple fraction of the pre-BMP load. The Bay Model combines a three-dimensional curvilinear hydrody- namic model (CH3D) with an eutrophication model (CE-QUAL-ICM) and computes the concentrations of nutrients and suspended sediment that result from the Watershed Model inputs, the quantity of phytoplankton that grow and decay, and the resulting water clarity and dissolved oxygen (DO) concentrations. In addition, the quantities of submerged aquatic vegetation (SAV) and water column (zooplankton) and benthic (deposit and filter feeding) organisms are also computed as well as specific simulations of oyster and menhaden populations. Modeled estimates of
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19 INTRODUCTION DO, chlorophyll, and light attenuation are used to determine if Bay water quality standards for DO, chlorophyll a, and water clarity have been vio- lated. The models of the watershed and estuary have been continuously developed and refined over a 25-year period (Table 1-1) (Linker et al., 2000, 2002, 2008). The Land Use Change Model and Scenario Builder are used to construct input scenarios for the Watershed Model to analyze current loads and forecast future loads under various land-use conditions. The Land Use Change Model provides annual time series of land use in the watershed and forecasts the land-use changes expected through 2030. Scenario Builder converts the numerous BMPs, which have various pol- lution reduction efficiencies depending on type and location in the water- shed, to a common currency of nitrogen and phosphorus load that will be generated by a given land use and estimates the area of soil available to be eroded. Loads are input to the Watershed Model to generate mod- eled estimates of loads delivered to the Bay (EPA, 2010a). The linkages between these models are illustrated in Figure 1-3. FIGURE 1-3 Key models used in the1-3.eps Figure Chesapeake Bay Program. bitmap SOURCE: EPA (2010a).
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20 TABLE 1-1 Historical Development of the Watershed and Bay Models Watershed Model Bay Model Notable Period of Management Model Revisions Characteristics Characteristics Advances Simulation Decisions Supported Phase 1 (1985) Based on HSPF. Steady state First coupling 4-month General goal of 40% Contained 5 land of watershed, summer of controllable loads uses, 64 segments hydrodynamic, simulation (CBP, 1987) and water quality only of 3 years models (1965, 1984, and 1985) Phase 2 (1992) Expanded Dynamic 4,000 First integrated 4 continuous Nutrient load agriculture grid cell model sediment flux years (1984- reductions to simulation detail model; first 1987), hourly achieve CBP (1987) inclusion of time step goals atmospheric deposition. Phase 4.3 (2003) 9 land uses, Dynamic 13,000 Integrated 14 continuous Expanded nutrient 94 watershed grid cell model simulation of years (1985- allocations segments land and soil 1994), hourly contaminant time step runoff processes; SAV, benthic deposit, and filter feeders models Phase 5.3 (2010) 25 land uses Dynamic 57,000 Enhanced 21 continuous TMDL (time variable), grid cell model segmentation, years 899 watershed land uses, and (1985-2005) segments mechanistic detail SOURCE: EPA (2010b); L. Linker, EPA, personal communication, 2011.
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21 INTRODUCTION BOX 1-2 Forms of Atmospheric Nitrogen Total oxidized reactive nitrogen, NOy NOy = NO + NO2 + NO3 + HNO3 + N2O5 + HONO + organic nitrates + particulate nitrates Nitrogen oxides, NOx NOx = NO + NO2 Reduced inorganic nitrogen, NHx NHx = NH3 + NH4 Unreactive nitrogen: N2 compounds except N2O) primarily results from combustion sources (see Box 1-2). Atmospheric deposition of reduced inorganic nitrogen (NHx; ammo- nia [NH3] + aerosol ammonium [NH4]; Box 1-2) primarily results from agricultural sources, such as manure. Sources internal to the watershed are primarily natural biological nitrogen fixation (e.g., soils) and cultivation- induced nitrogen fixation (e.g., soybeans).2 For the Bay itself, the primary internal source is biological nitrogen fixation. Nitrogen that originates from sources internal and external to the watershed is delivered to the Bay waters by atmospheric deposition, direct discharges from wastewater treatment plants and stormwater systems, and groundwater and riverine inputs. Once introduced into the watershed, the fate of nitrogen is dependent upon its source. A large fraction of the nitrogen from municipal and indus- trial wastewater point sources and urban runoff, which can be categorized either as a nonpoint source or regulated point source,3 is rapidly trans- 2 Nitrogen fixation is a natural process by which unreactive nitrogen (N2) in the atmosphere is converted to biologically available ammonia by enzymatic reduction. 3 The Clean Water Act (CWA) defines a point source of water pollution as “any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged.” Federal regulations require that all point sources meet discharge limitations provided for in National Pollutant Discharge Elimination System (NPDES) permits. More recently, stormwater runoff in urban areas meeting certain population density criteria or land use conditions has been defined as a regulated point source requiring an NPDES permit. Some urban and agricultural sources that are categorized as point sources under the CWA may be indistinguishable from unregulated nonpoint sources, both in terms of character and the management practices that may be effective in their control. The only difference is often size and whether a NPDES permit has been issued. To avoid confusion in this report, especially for readers who may
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22 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY ported to the Bay. Of the nitrogen introduced into agricultural systems, most is used in the system and then lost to the atmosphere, discharged into an aquatic system, or stored in the soil. Less than 50 percent is actu- ally incorporated into feed or food (Smil, 1999; Cassman et al., 2002). If nitrogen infiltrates into groundwater (e.g., from a septic system leach field or agricultural fertilizers), then it potentially could be stored for significant lengths of time (i.e., years to decades) before it is discharged to surface waters (Phillips and Lindsey, 2003; Lindsay et al., 2003; see Box 1-3). Reactive nitrogen is lost from the watershed system by denitrification within the watershed and its waters and by export. Denitrification converts nitrate primarily to nitrogen gas (N2), with smaller amounts of N2O and NO produced. N2 formation represents a conversion of reactive nitrogen to an unreactive nitrogen form and thus removes the nitrogen from interac- tion with the earth systems’ processes for millions of years. N2O and NO formation, however, represent the conversion of one type of reactive nitro- gen to other types of reactive nitrogen, each with their own environmental impacts. The amount of NO formed by denitrification is small compared to the NO formed from fossil fuel combustion within the watershed. In contrast, denitrification forms the primary source of N2O, a potent green- house gas, within the Bay and its watershed (Galloway et al., 2004, 2008). Overall, how much denitrification occurs in the Bay watershed remains the largest uncertainty of the nitrogen cycle. Nitrogen is exported out of the watershed through three pathways: (1) atmospheric advection of the nitrogen emitted to the watershed’s atmo- sphere, (2) hydrologic transport of nitrogen to the coastal ocean in the waters leaving the Bay, and (3) shipment from the watershed of nitrogen- containing commodities that are produced in the Bay (e.g., shellfish, fish) or its watershed (e.g., food, feed). Estimates of Nitrogen Source Loads to the Bay Approximately 400 million pounds (181 million kg) of nitrogen com- pounds emitted to the atmosphere are deposited on the Bay’s watershed each year, with approximately 68 percent coming from NOy and 32 per- cent from NHx (R. Dennis, EPA, personal communication, 2011). Sources of atmospheric nitrogen are described in Box 1-4. Most of the deposited nitrogen is retained by forests or other vegetation and in other biological not be as familiar with federal regulatory programs, the terms “point” and “nonpoint” will be appropriately qualified as to origin, i.e., “municipal” and/or “industrial” point sources,” “urban” and/or “agricultural” point or nonpoint sources. In many cases, it is expeditious to aggregate urban and agricultural point sources and nonpoint sources, in which case the terms “urban runoff” and “agricultural runoff” are used to incorporate the two but do not include discharges from municipal or industrial wastewater treatment facilities.
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23 INTRODUCTION processes before it reaches the Bay. Of all the atmospheric nitrogen that is deposited on the watershed annually, the Watershed Model estimates that approximately 75 million pounds (34 million kg) actually reach the Bay’s tidal waters, largely washed off impervious surfaces. Another 19 million pounds (8.6 million kg) are deposited directly on the Bay’s tidal waters, for a total of approximately 94 million pounds (43 million kg) or 33 per- cent of the total nitrogen load to the Bay (CBP, 2010a; Figure 1-4). Of the nitrogen that enters the watershed, that which is not quickly discharged to the Bay or denitrified to N2 is stored in the watershed in groundwater and can potentially be released to the Bay in the future (also called legacy nitrogen; see Box 1-3). FIGURE 1-4 Sources of nitrogen to Chesapeake Bay. NOTES: Based on model simulations using the Watershed Model Phase 4.3 and the Airshed Model, considering land use and pollution control measures in place as of 2007. The data reflects the average output when simulated over 14 years of hydrologic record and does not include loads from the ocean or tidal shoreline erosion. Atmospheric deposition loads are categorized by the source of the atmo- spheric nitrogen, except for the deposition directly to tidal waters, which includes all sources. For example, agricultural atmospheric deposition includes the atmospheric deposition that emanates from agricultural lands. Wastewater loads are based on measured discharges. SOURCE: CBP (2010a).
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48 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY 400 350 NTWDep Total Nitrogen (M lbs/year) Forest Septic 300 Point Source Urban runoff Agriculture 250 200 150 100 50 0 1985 2009 Trib. Strategy TMDL E3 30 NTWDep Forest Total Phosphorus (M lbs/year) 25 Septic Point Source Urban runoff 20 Agriculture 15 10 5 0 1985 2009 Trib. Strategy TMDL E3 12000 NTWDep Forest 10000 Total Sediment (M lbs/year) Septic Point Source Urban runoff 8000 Agriculture 6000 4000 2000 0 1985 2009 Trib. Strategy TMDL E3 Figure 1-13.eps
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49 INTRODUCTION RECENT INITIATIVES (2008-2010) Recognition that the CBP would again fail to meet its goals set in the 2000 Agreement (CBP, 2000), combined with a highly critical review by the Government Accountability Office (GAO, 2005), led to a renewed focus on accountability and tracking of progress in the restoration process. In its 2005 report, GAO stated: The Bay Program does not have a comprehensive, coordinated implemen- tation strategy to better enable it to achieve the goals outlined in Chesa- peake 2000. Although the program has adopted ten key commitments to focus partners’ efforts and developed plans to achieve them, some of these plans are inconsistent with each other or are perceived as unachievable by program partners. In addition, the GAO questioned the effectiveness and credibility of the CBP’s annual progress reports, which had not clearly distinguished monitoring results from model projections. To address these concerns, the CBP developed the Chesapeake Action Plan (CAP), which was intended to enhance coordination and engagement among CBP partners, increase the CBP’s transparency, and heighten the CBP’s accountability (CBP, 2008). The Obama administration injected new energy into Bay restoration efforts. On May 12, 2009, President Obama released an executive order directing the federal government to lead restoration efforts and the EPA FIGURE 1-13 Average annual (a) total nitrogen loading, (b) total phosphorus load- ing, and (c) total sediment loading (in million lbs/yr) delivered to Chesapeake Bay as estimated in five scenarios of the Phase 5.3 Watershed Model (see Table 1-1). SOURCE: S. Ravi, CBPO, personal communication, 2011. NOTES: The scenarios are modeled using the same hydrologic conditions (1985- 2005) and changing land use, point source, and BMP conditions. The scenarios include 1985 baseline conditions, 2009 progress, the tributary strategy (TS) goals based on the cap loads set in 2003, total maximum daily load (TMDL), and maxi- mum feasible reduction (E3) scenarios. The E3 scenario is a “what if” scenario of watershed conditions with theoretical maximum levels of managed controls on load sources (“everything, by everyone, everywhere”), with no cost and few physical limitations to implementing BMPs for point and nonpoint sources. Source sec- tors include agriculture, urban runoff, point sources (including wastewater), septic systems, forested lands, and non-tidal waters atmospheric deposition (NTW Dep). Note that in these bar graphs, atmospheric deposition is considered separately only when it falls directly on non-tidal waters; otherwise, the source is attributed to the land-use type on which the deposition falls. The data are also provided in Appendix A.
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50 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY to coordinate efforts with several federal agencies, in collaboration with state governments, to reduce pollutants flowing into the Bay (Executive Order 13508). In response, by November 2009, federal CBP partners had completed reports that outlined a new state and federal accountability framework and actions to reduce pollution and improve compliance (DOD, 2009; DOI, 2009; DOI and DOC, 2009a,b,c; EPA, 2009; USDA, 2009). Chesapeake Bay Total Maximum Daily Load (TMDL) A TMDL, or total maximum daily load, is defined as the maximum allowable load of a pollutant that a water body can receive while still meet- ing its water quality standard. Under President Obama’s executive order, the EPA Administrator was charged with developing a management plan to address the negative consequences of nutrient and sediment loading into the Chesapeake Bay. Under the lead of EPA Region III, a multistate TMDL analysis was conducted. The Bay jurisdictions produced watershed imple- mentation plans (WIPs) in support of the TMDL. The EPA established the final TMDL in December 2010. The EPA established the Chesapeake Bay TMDL in response to a number of existing authorities, including the CWA, several judicial consent decrees, a settlement agreement resolving litigation brought by the Chesa- peake Bay Foundation, the 2000 Agreement, and Executive Order 13508. The TMDL’s executive summary identifies the effort as “…a ‘pollution diet’ that will compel sweeping actions to restore the Chesapeake Bay and its vast network of streams, creeks and rivers” (EPA, 2010a). Further, the TMDL addresses three pollutants—nitrogen, phosphorus, and sediment— related to dissolved oxygen and water clarity standards necessary to restore the Bay ecosystem. The TMDL articulates the following expectation: “The TMDL is designed to ensure that all pollution control measures to fully restore the Bay and its tidal rivers are in place by 2025, with 60 percent of the actions completed by 2017” (EPA, 2010a). The TMDL stipulates Bay watershed load limits of 185.9 million pounds (85.3 million kg) of nitrogen, 12.5 million pounds (5.67 million kg) of phosphorus, and 6.45 billion pounds (2.93 billion kg) of sediment per year based on average hydrologic conditions during the 1985-2005 period. These loads represent a 24 percent reduction in nitrogen and phos- phorus and a 20 percent reduction in sediment from the model-simulated loads based on 2009 land use conditions (EPA, 2010a). These loads are allocated among the seven Bay jurisdictions. The overall TMDL nutrient and sediment reduction goals reflect relatively small modifications to the cap load goals set in 2003 (EPA, 2003). The TMDL supports the CBP’s goal of removing the Bay from the EPA’s list of impaired waters. The Bay TMDL covers a larger area than any other U.S. TMDL.
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51 INTRODUCTION Although EPA lists over 4,700 nutrient TMDLs nationwide that have been established since October 1995, relatively few address estuaries.9 However, the Chesapeake Bay TMDL is within the range of reductions (by percent- age) for several other estuaries, including the nutrient TMDL for New York and Connecticut’s Long Island Sound (58.5 percent reduction in nitrogen discharges from the adjusted 1990 baseline load; NYS DEC and CT DEP, 2000), the Caloosahatchee Estuary in Florida (23 percent reduction in total nitrogen loading; Bailey et al., 2009) and Newport Bay in California (50 percent reduction from current nutrient and sediment loadings; EPA, 2002). Watershed implementation plans (WIPs), developed by the seven Bay jurisdictions, define how and when they will meet their nitrogen, phospho- rus, and sediment load allocations. The EPA will evaluate WIP implemen- tation and the Bay jurisdictions’ progress toward meeting their two-year milestones (described in the next section). If implementation progress is insufficient, the EPA can take appropriate “backstop measures” to ensure compliance with the TMDL. Backstop measures can include targeted enforcement actions on regulated sources, expansion of requirements to obtain discharge permits for currently unregulated sources, or additional reductions from federally permitted sources of pollution (e.g., wastewater treatment plants, large animal operations, municipal stormwater systems) (EPA, 2010a). The Bay jurisdictions will submit draft Phase II WIPs that provide local area nutrient allocations on a smaller scale by December 2011. Phase II WIPs are expected to include roles for local governments and munici- palities, especially for managing nutrient loading from urban and suburban areas (EPA, 2010a). Two-Year Milestones To accelerate progress and increase accountability in the Bay restora- tion, the CBP introduced a two-year milestone strategy for nutrient load reductions in May 2009. In the past, Bay recovery goals involved decadal increments and did not identify specific strategies for achieving the neces- sary pollution reductions. The prior decadal goals were characterized as “ladder[s] without rungs” (CBP, 2009b). In addition, elected officials were not held accountable for attaining the goals because the timeframes for achieving them often extended beyond their terms of office. As a result, progress was sluggish, and major goals were not met (CBP, 2009b). The two-year milestone program introduced a revised strategy aimed at reduc- ing overall pollution in the Bay by focusing on short-term, incremental implementation goals. The CBP envisioned that through a series of two- 9 See http://www.epa.gov/waters/ir/index.html.
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52 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY year milestone periods with routine assessments of the pace of progress, by 2025 the Bay jurisdictions could implement all of the nutrient and sediment control practices needed for a restored Bay, although actual Bay water qual- ity response and recovery likely will lag behind the 2025 implementation target. The two-year milestone strategy required each Bay jurisdiction to com- mit to an initial suite of actions in the first milestone period to be completed by December 31, 2011. The jurisdictions identified specific actions, includ- ing application of land-based BMPs and wastewater treatment facility upgrades, anticipated to keep them on track to meet the long-term imple- mentation goals by 2025. Each Bay jurisdiction also identified contingency actions that could be taken if some of the primary nutrient reduction practices could not be implemented in this timeframe. The CBP aims ulti- mately to reduce nitrogen and phosphorus loading in the watershed by 15.8 million pounds (7.2 million kg) and 1.1 million pounds (500 thousand kg), respectively, by actions completed during the first milestone (CBP, 2009b). If all proposed actions are implemented, the first milestone actions are anticipated to ultimately provide about 21 percent of the nitrogen load reduction and 22 percent of the phosphorus load reduction needed to meet the Tributary Strategy cap loads (Table 1-5). See Box 1-5 for a Bay-wide summary of the first milestone actions. Reductions for nitrogen and phos- phorus in the first milestone period are shown by sector in Figure 1-14. No sediment milestone was set for the first milestone period (2009- 2011) because of uncertainties in the overall sediment target at the time, although sediment milestones are expected to be added for the next two- year milestone (2012-2013). Many of the two-year milestone measures to control nutrient loading, however, will also significantly reduce sediment loading. The Bay jurisdictions are currently developing strategies for the sec- ond milestone period. Through tracking and accounting mechanisms (see Chapter 2), the CBP will assess each Bay jurisdiction’s implementation progress toward the two-year milestones. Given lags between land-based BMP implementation and nutrient and sediment reduction in the Bay (see Box 1-3), the CBP primarily assesses progress toward the two-year mile- stone goals by tracking implementation of practices rather than monitoring nutrient loads in streams. Integrating Two-Year Milestones, Watershed Implementation Plans, and the TMDL for Chesapeake Bay Although the two-year milestones were originally conceived as steps toward meeting the cap load goals, they are now being used as measures of incremental progress toward meeting the TMDL WIP goals for 2017
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TABLE 1-5 Estimated Contribution of the First Milestone Toward Reductions to Meet Tributary Strategy Cap Loads Model-estimated Average Load based Tributary Strategy 2009-2011 Percentage of Load on 2008 Progress Cap to Meet Water Reduction Required Estimated Milestone Reduction to meet Run Quality Standards by 2025 Reduction Tributary Strategy Cap (million pounds (million pounds (million pounds (million pounds Loads Targeted in First per year) per year) per year) per year) Milestone Nitrogen 258.5 183.1 75.4 15.8 21.0 Phosphorus 17.8 12.8 5.0 1.1 22.1 Sediment 9,500 8,293 1,207 NA NA NOTES: All load estimates, including the Tributary Strategy cap loads, were developed based on Phase 4.3 of the Chesapeake Bay Watershed Model. The TMDL (EPA, 2010a) was developed using Phase 5.3, and therefore, for consistency, the overarching goals are presented in terms of the Tributary Strategy goals. The original milestone commitments would need to be simulated using the Phase 5.3 Watershed Model to calculate the percentage of the TMDL to be accomplished by the first milestone. SOURCES: CBP (2009b); K. Antos, CBPO, personal communication, 2011. 53
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54 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY BOX 1-5 Best Management Practices to Be Implemented in First Milestone Period (2009-2011) across the Chesapeake Bay Watershed The following best management practices represent the sum of total activities to be implemented under the first milestone period in the Chesapeake Bay watershed. Agriculture Nutrient Management 1,082,251 acres Conservation Tillage 306,991 acres Cover Crops 652,152 acres/year Pasture Grazing BMPs 168,800 acres Streamside Forest Buffers 39,110 acres Streamside Grass Buffers 14,910 acres Forest Harvesting Practices 125 acres Wetland Restoration 3,809 acres Land Retirement 81,676 acres Tree Planting 27,965 acres Carbon Sequestration/Alternative Crops 25,740 acres Conservation Plans/SCWQP 584,648 acres Animal Waste Management Systems 1,016 systems Mortality Composters 22 systems Water Control Structures 25,000 acres Horse Pasture Management 300 acres Non-Urban Stream Restoration 232,088 feet Poultry Phytase 19,626 fewer pounds P and 2025. The milestones are intended to improve accountability and allow for adjustments if needed. These issues are discussed in more detail in Chapter 3. A summary of how the two-year milestone strategy is incorporated into the existing Bay restoration goals and TMDL accountability framework is depicted in Figure 1-15. In the two-year milestones, Bay jurisdictions identify practices to be implemented during every 2 year period until 2025. WIPs present cumulative practice implementation goals for 2017 (Phase 1) and 2025 (Phase 2).The TMDL defines the total load reductions (nitrogen, phosphorus, and sediment) necessary to meet water quality criteria. The ultimate goal is to meet the ecological endpoints associated with a fully restored Bay (extent of underwater grasses, fisheries abundance, and diver-
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55 INTRODUCTION Manure Transport 131,503 net tons Dairy Precision Feeding and/or 291,203 pounds N Forage Management 51,264 pounds P Heavy Use Poultry Area Concrete Pads 400 farms Livestock and Poultry Waste Structures 198 structures Dairy and Poultry Manure Incorporation Technology 5,000 acres Wastewater 1,887,350 pounds nitrogen reduced 201,500 pounds phosphorus reduced Urban/Suburban Urban Stormwater Management 148,740 acres Tree Planting 30 acres Urban Stream Restoration 18,656 feet Erosion and Sediment Control 62,731 acres Nutrient Management 133,000 acres Wetland Restoration 350 acres Abandoned Mine Reclamation 2,219 acres Dirt and Gravel Road Erosion 124,913 feet Septic Improvements 27,125 systems Air Heavy Truck Anti-Idling Rule 9.78M hours reduced NOx Reductions 56,000 tons Maryland Healthy Air Act 305,882 fewer pounds N/year SOURCE: CBP (2009b). sity and other natural resource goals), as defined by the CBP (see Table 1-2). The EPA will review progress toward these two-year milestones, in the context of the TMDL, and will evaluate whether sufficient actions are being planned and undertaken to achieve the necessary pollution reductions (EPA, 2010a). STATEMENT OF COMMITTEE TASK AND REPORT OVERVIEW In 2009, the NRC’s Committee on the Evaluation of Chesapeake Bay Program Implementation for Nutrient Reduction to Improve Water Qual- ity was formed to undertake an evaluation of the CBP’s nutrient reduction program and to respond to the GAO (2005) recommendation for indepen-
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56 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY FIGURE 1-14 Percentage of nutrient reductions planned in the first milestone period from agriculture, wastewater, urban/suburban, air, and other sectors. SOURCE: CBP (2009b). Figure 1-14.eps bitmap Restoration of underwater grasses, fisheries, benthic communities, and Ecological faunal diversity Endpoints Meet Bay water quality criteria for dissolved oxygen, clarity, and chlorophyll-a concentrations; 60 percent of Bay segments attaining Water standards by 2025. Quality Criteria Chesapeake Bay total maximum daily load: Achieve loads of 185.9 Load million lbs/yr N, 12.5 million lbs/yr P, and 6.45 billion lbs/yr sediment. Reduction Goals: TMDL Watershed implementation plans: Have in place by 2025 all practices needed to meet TMDL limits; 60 percent in place by 2017. Practice Two-year milestones: At the end of each two-year milestone period, Implementation have in place all practices planned for that period. Goals Figure 1-15.eps FIGURE 1-15 Integration of the goals and strategies used in the CBP, including two-year milestones and the TMDL accountability framework.
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57 INTRODUCTION dent review to enhance the credibility and objectivity of its reports. This study was sponsored by the EPA, with additional funding support from the states of Virginia, Maryland, Pennsylvania, and the District of Columbia. The committee was specifically tasked to address the following questions, broken down into two themes: Evaluation Theme I: Tracking and Accountability 1. Does tracking for implementation of nutrient and sediment point and nonpoint source pollution (including air) best management practices ap- pear to be reliable, accurate, and consistent? 2. What tracking and accounting efforts and systems appear to be work- ing, and not working, within each state (i.e., the six states in the watershed and DC), including federal program implementation and funding? How can the system be strategically improved to address the gaps? 3. How do these gaps and inconsistencies appear to impact reported pro- gram results? Evaluation Theme II: Milestones 4. Is the two-year milestone strategy, and its level of implementation, likely to result in achieving the CBP nutrient and sediment reduction goals for this milestone period? 5. Have each of the states (i.e., the six states in the watershed and DC) and the federal agencies developed appropriate adaptive management strategies to ensure that CBP nutrient and sediment reduction goals will be met? 6. What improvements can be made to the development, implementation, and accounting of the strategies to ensure achieving the goals? It is important to note, as discussed further in Chapter 2, that the com- mittee charge (particularly Task 4) focuses on implementation of strategies during the two-year milestone period, rather than on actual water quality improvement during this period. Realistically, interannual variability and delayed responses preclude the determination of conclusive relationships between action and water quality improvement for such a short increment of time. Additionally, because there are no milestones for sediment dur- ing the first reporting period, which the committee was tasked to analyze, the committee places greater emphasis on issues affecting nutrient loads, although sediment issues are included throughout and have been more recently quantified in the 2010 TMDL. Although most of the tasks are narrowly focused, the committee took a broad view in its interpretation of Task 6 on what improvements can be made to the development, implementation, and accounting of the strategies
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58 NUTRIENT AND SEDIMENT REDUCTION GOALS IN THE CHESAPEAKE BAY to ensure achieving the goals. The committee considered “the goals” to include the long-term nutrient and sediment reduction goals and subsequent recovery of the Bay ecosystem, not just the first two-year milestone goals. In addition, the committee considered both practices and policies that could improve the likelihood of achieving the goals, because the feasibility of implementing specific practices is often affected by broader policy decisions. The committee’s conclusions and recommendations are based on a review of relevant technical literature, briefings, and discussions at its four meetings and the experience and knowledge of the committee members in their fields of expertise. Following this brief introduction, the statement of task is addressed in four subsequent chapters of this report: • In Chapter 2, the committee assesses the tracking and accounting for BMPs and infrastructure upgrades for nutrient and sediment control and identifies key issues facing the Bay jurisdictions and the CBP (Tasks 1, 2, and 3). The committee also identifies ways to improve tracking and accounting procedures. • In Chapter 3, the committee evaluates the two-year milestone strategy and, based on the information presented, discusses the likelihood of achieving the nutrient reduction goals for the first milestone period (Task 4). • In Chapter 4, the committee assesses the CBP’s adaptive manage- ment approaches (Task 5), and identifies the challenges to and opportunities for using adaptive management to meet nutrient and sediment reduction goals. • In Chapter 5, the committee describes overarching issues affect- ing achievement of the nutrient reduction goals (Task 6), and discusses improvements that, if implemented, could enhance the likelihood of achiev- ing the program goals.