Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
5 Adaptive Implementation for Impaired Waters Water quality assessment is a continuous process. The finding of an impaired waterbody during assessment triggers a sequence of events that may include listing of the water, development of a Total Maximum Daily Load (TMDL), planning of state and federal actions, and implementation events designed to comply with water quality standardsâall of which are characterized by uncertainty. This chapter describes the process of adap- tive implementation of a water quality plan. Adaptive implementation simultaneously makes progress toward achieving water quality standards while relying on monitoring and experimentation to reduce uncertainty. SCIENCE AND THE TMDL PROCESS The planning sequence of moving from data to analysis to informa- tion and knowledge is supposed to provide confidence that the some- times costly actions to address a water quality problem are justified. A desire for this confidence is often behind the call for âsound scienceâ in the TMDL program. However, the ultimate way to improve the scien- tific foundation of the TMDL program is to incorporate the scientific method, not simply the results from analysis of particular data sets or models, into TMDL planning. The scientific method starts with limited data and information from which a tentatively held hypothesis about cause and effect is formed. The hypothesis is tested, and new under- standing and new hypotheses can be stated and tested. By definition, science is this process of continuing inquiry. Thus, calls to make policy decisions based on the âthe science,â or calls to wait until âthe science is complete,â reflect a misunderstanding of science. Decisions to pursue some actions must be made, based on a preponderance of evidence, but there may be a need to continue to apply science as a process (data col- lection and tools of analysis) in order to minimize the likelihood of future 89
90 Assessing the TMDL Approach to Water Quality Management errors. Many debates in the TMDL community have centered on the use of âphasedâ and âiterativeâ TMDLs. Because these terms have particular meanings, this report uses a more general termâadaptive implementa- tion. Adaptive implementation is, in fact, the application of the scientific method to decision-making. It is a process of taking actions of limited scope commensurate with available data and information to continuously improve our understanding of a problem and its solutions, while at the same time making progress toward attaining a water quality standard. Plans for future regulatory rules and public spending should be tentative commitments subject to revision as we learn how the system responds to actions taken early on. Like other chapters, this chapter discusses a framework for water quality management (shown in Figure 5-1, which is the same as Figure 3-1). Before turning to adaptive implementation, it discusses an impor- tant prior stepâreview of water quality standards. Before a waterbody is placed on the action (303d) list, it is suggested that states conduct a re- view of the appropriateness of the water quality standard. The standards review may result in the water not being listed as impaired if the standard used for the assessment was found to be inappropriate. On the other hand, the same process may result in a âstricterâ standard than was used in the assessment process, in which case the waterbody would have a TMDL plan developed to achieve that revised standard. A review of the water quality standard will assure that extensive planning and imple- mentation actions are directed toward clearly conceived designated uses and associated criteria to measure use attainment. REVIEW OF WATER QUALITY STANDARDS Water quality standards are the benchmark for establishing whether a waterbody is impaired; if the standards are flawed (as many are), all sub- sequent steps in the TMDL process will be affected. Although there is a need to make designated use and criteria decisions on a waterbody and watershed-specific basis, most states have adopted highly general use designations commensurate with the federal statutory definitions. How- ever, an appropriate water quality standard must be defined before a TMDL is developed. Within the framework of the Clean Water Act (CWA), there is an opportunity for such analysis, termed use attainability analysis (UAA).
Adaptive Implementation for Impaired Waters 91 All Waters Determine Designated Use/ Standard Screening Assessment âPreliminaryâ List Full Review Use/ Assessment Standard âActionâ List (303d) TMDL Planning Adaptive Implementation FIGURE 5-1 Framework for water quality management.
92 Assessing the TMDL Approach to Water Quality Management A UAA determines if impairment is caused by natural contaminants, nonremovable physical conditions, legacy pollutants, or natural condi- tions (see Box 5-1). More importantly, a UAA can refine the water qual- ity standard. UAA should result in more stratified and detailed narrative statements of the desired use and measurable criterion. For example, a UAA might refine the designated use and criterion from a statement that the water needs to be fishable to a statement calling for a reproducing trout population. Then one or more criteria for measuring attainment of this designated use are described; these might include minimum dis- solved oxygen or maximum suspended sediment requirements. Alterna- tively, an index to measure biological condition appropriate to the trout fishery designated use, such as an index of biological integrity (IBI), may be defined. In the 1990s, TMDLs were undertaken for some waterbodies where the designated use was not attainable for reasons that could have been disposed of by a UAA. For example, TMDLs conducted in Louisiana resulted in the conclusion that even implementing zero discharge of a pollutant would not bring attainment of water quality standards (Houck, 1999). A properly conducted UAA would have revealed the true prob- lemânaturally low dissolved oxygen concentrationsâbefore the time and money were spent to develop the TMDL. Unfortunately, UAA has not been widely employed. Novotny et al. (1997) found that 19 states reported no experience with UAA. The majority of states reported a few to less than 100 UAAs, while five states (Indiana, Nebraska, New York, Oklahoma, and Pennsylvania) performed more than 100. One possible explanation for the failure to widely employ UAA analysis is the absence of useful EPA guidelines. The last technical sup- port manuals were issued in the early 1980s (EPA, 1983) and are limited to physical, chemical and biological analyses. It is presently not clear what technical information constitutes an adequate UAA for making a change to the use designation for a waterbody that will be approved by the EPA. In addition to being a technical challenge, standards review also has im- portant socioeconomic consequences (see point 6 in Box 5-1). EPA has provided little information on how to conduct socioeconomic analyses or how to incorporate such analyses in the UAA decision. The socioeco- nomic analysis suggested by EPA is limited to narrowly conceived finan- cial affordability and economy-wide economic impact assessments (e.g., employment effects) (Novotny et al., 1997). However, when setting wa- ter quality standards, states may be asked to make decisions in
Adaptive Implementation for Impaired Waters 93 BOX 5-1 Six Reasons for Changing the Water Quality Standard The following six situations, which can be revealed by UAA, consti- tute reasons for changing a designated use or a water quality standard (EPA, 1994). Conducting a UAA does not necessarily preclude the de- velopment of a TMDL. 1. Naturally occurring pollutant concentrations prevent attainment of the use. 2. Natural, ephemeral, intermittent, or low flow water levels prevent the attainment of the use unless these conditions may be compensated for by a sufficient volume of effluent discharge without violating state conservation requirements to enable uses to be met. 3. Human-caused conditions or sources of pollution prevent the at- tainment of the use and cannot be remedied or would cause more envi- ronmental damage to correct than to leave in place (e.g., as with some legacy pollutants). 4. Dams, diversions, or other types of hydrologic modifications pre- clude the attainment of the use, and it is not feasible to restore the wa- terbody to its original condition or to operate such modification in a way that would result in the attainment of the use. 5. Physical conditions related to the natural features of the water- body, such as the lack of proper substrate, cover, flow, depth, pools, rif- fles, and the like, unrelated to water quality, preclude attainment of aquatic life protection uses. 6. Controls more stringent that those required by the CWA manda- tory controls (Sections 301b and 306) would result in substantial and widespread adverse social and economic impact. This requires devel- oping a TMDL and conducting a socioeconomic impact analysis of the resulting TMDL (Novotny et al., 1997). consideration of a broader socioeconomic benefitâcost framework than what is currently expected in a UAA. Finally, EPA has offered no guid- ance on what constitutes an acceptable UAA in waterbodies of different complexity and on what decision criteria will be accepted as a basis for changing a use designation. This is significant because EPA retains the authority to approve state water quality standards. These uncertainties discourage state use of UAA because there is no assurance that EPA will accept the result of the UAA effort as an alternative to a TMDL, espe- cially if the EPA expectation for a UAA will result in significant analyti- cal costs.
94 Assessing the TMDL Approach to Water Quality Management Conclusions and Recommendations 1. EPA should issue new guidance on UAA. This should incorpo- rate the following: (1) levels of detail required for UAAs for waterbodies of different size and complexity, (2) broadened socioeconomic evaluation and decision analysis guidelines for states to use during UAA, and (3) the relative responsibilities and authorities of the states and EPA in making use designations for specific waterbodies following a UAA analysis. 2. UAA should be considered for all waterbodies before a TMDL plan is developed. The UAA will assure that before extensive planning and implementation actions are taken, there is clarity about the uses to be secured and the associated criteria to measure use attainment. UAA is especially warranted if the water quality standards used for the assess- ment were not well stratified. However, the decision to do a UAA for any waterbody should rest with each state. ADAPTIVE IMPLEMENTATION DESCRIBED Once a waterbody is on the 303d list, a plan to secure the designated use is developed and a sequence of actions is implemented. The adaptive implementation process begins with initial actions that have a high de- gree of certainty associated with their water quality outcome. Future actions must be based on (1) continued monitoring of the waterbody to determine how it responds to the actions taken and (2) carefully designed experiments in the watershed. This concurrent process of action and learning is depicted in Figure 5-2. The plan includes the following related elements: immediate actions, an array of possible long-term actions, success monitoring, and experi- mentation for model refinement. In choosing immediate actions, water- shed stakeholders and the state should expect such actions to be under- taken within a fixed time period specified in the plan. If the impairment problem is attributable to a single cause or if the impairment is not se- vere, then the immediate actions might be proposed as the final solution to the nonattainment problem. However, in more challenging situations, the immediate actions alone should not be expected to completely elimi- nate the impairment. Regardless of what immediate actions are taken, there may not be an immediate response in waterbody or biological condition. For example,
Adaptive Implementation for Impaired Waters 95 TMDL Plan Immediate and Experiments Model Long-term Actions/ Refinement Monitoring no Meeting Designated Use? yes Back to initial list of all waters for continuing assessment in the rotating basin process FIGURE 5-2 Adaptive implementation flowchart. there may be significant time lags between when actions are taken to re- duce nutrient loads and resulting changes in nutrient concentrations. This is especially likely if nutrients from past activities are tightly bound to sediments or if nutrient-contaminated groundwater has a long resi- dence time before its release to surface water. For many reasons, lags between actions taken and responses must be expected. As discussed below, the waterbody should be monitored intensively to establish whether the âtrajectoryâ of the measured water quality criterion points toward attainment of the designated use. Longer-term actions are those that show promise, but need further evaluation and development. They should be formulated in recognition of emerging and innovative strategies for waterbody restoration. The commitment in the plan is to further evaluate such actions based on the collection of additional data, data analysis, and modeling. An adaptive implementation plan would specify analyses of specific long-term alter-
96 Assessing the TMDL Approach to Water Quality Management natives, a schedule for such analyses to be conducted, and a mechanism for supporting such analyses. Success monitoring follows after implementation actions. If success monitoring shows that the waterbody is meeting water quality standards including designated uses, then no further implementation actions would be taken. Waterbodies should be returned to the âall watersâ list (see Figure 5-1) where they will be monitored as a part of the rotating basin process. A primary purpose of success monitoring is to establish com- pliance with water quality standards and ultimately make the delisting decision. Because state ambient monitoring programs typically have limited resources, it may be necessary to design and implement success monitoring for the TMDL program outside the rotating basin process. Those stakeholders affected by 303d listing and TMDL development may have an incentive to make a significant contribution to the monitor- ing effort to assure that the water is truly impaired and that the best pos- sible models are being used for plan development. Stakeholder moni- toring would be conducted with input on its design by the state. One of the most important applications of success monitoring data is to revise and improve the initial TMDL forecast over time. This revision of the TMDL model can be formally accomplished using techniques such as Bayesian analysis, data assimilation, or Kalman filtering. For exam- ple, a TMDL for total phosphorus, based on a model forecast that in- cluded uncertainty analysis, might be implemented to address a chloro- phyll a standard violation. As part of the implementation program, monitoring would be undertaken to assess success and compliance. At the end of the five-year rotating basin cycle, the original chlorophyll a forecast could be combined with the monitoring-based chlorophyll a time trajectory to yield a revised forecast of ultimate chlorophyll a re- sponse. This revised forecast could provide the basis for changes to be implemented during the next five-year cycle in order to meet the water quality standard. Techniques to accomplish model refinement have existed for some time in a Bayesian context (Reckhow, 1985), and under various labels and modifications, they are being applied in other areas. For example, âdata assimilationâ (Robinson and Lermusiaux, 2000), a derivative of Bayesian inference, is being widely used in the earth sciences to augment uncertain model forecasts with observations. The Bayesian approach holds particular appeal for adaptive TMDLs because it involves âknowl- edge updatingâ that is based on pooling precision-weighted information.
Adaptive Implementation for Impaired Waters 97 The need for experimentation to be part of the plan depends on the complexity of the problem and the need to learn more about the system for subsequent model refinement and decision-making. Experiments can, for example, be developed to test the site-specific effectiveness and response time of best management practices (BMPs) (like riparian buff- ers), to determine the fate and transport of pollutants in runoff, or to an- swer other questions critical to model refinement. Experiments must be carefully designed and adequately supported (with both funding and staff) to study the effectiveness of actions in the watershed context and to study and learn about watershed processes that are not well understood. TMDL plans for waterbodies with relatively simple problems that can be addressed with high certainty about cause and effect might not include experimentation. All the actions described above can be used to refine the original TMDL plan so that it better reflects the current state of knowledge about the system and innovative modeling approaches. When revising the TMDL plan, water managers should consider whether the longer-term actions discussed above, or other new alternatives, should be imple- mented in addition to the immediate actions called for in the original plan. TMDL plans for complicated systems (e.g., a reservoir impacted by multiple nonpoint sources of pollution) can be expected to undergo more revisions before water quality standards (including designated uses) are met than will TMDL plans developed for simple systems. TMDL IMPLEMENTATION CHALLENGES Allocation Issues Plan implementation involves actions taken to reduce all the stressors responsible for the impairment. The allocation of financial and legal re- sponsibility for taking those actions will fall on stakeholders in the wa- tershed, who may not receive public subsidies for taking such actions. Because of these cost consequences, stakeholders want to be sure that water quality standards are appropriate and that total load limits and the limits proposed on other stressors (e.g., flow modifications) are neces- sary to secure the designated use. The committeeâs charge included a request to evaluate the reliability of âthe information required to allocate reductions in pollutant loadings
98 Assessing the TMDL Approach to Water Quality Management among sources.â Allocation is first and foremost a policy decision on how to distribute costs among different stakeholders in order to achieve a water quality goal. Consider a hypothetical example where three differ- ent actions are possible: reduction of pollutant loads from a treatment plant, reductions in pollutant load in runoff from urban areas and farm fields, and increases in stream flow from reduced consumptive irrigation water use. Also suppose that different combinations of all of these ac- tions can achieve the designated use. Allocation becomes a difficult de- cision because the different combinations will have a different total cost and different levels of perceived fairness. One suggestion might be to choose the combination of actions that minimizes total cost. However, this may result in a cost distribution that places most of the burden on the customers of the treatment plant (for example). An alternative may be to reduce loads from the plants and from runoff by the same proportion; however, this leaves unanswered whether any cost responsibility should fall on the irrigators. Other combinations of actions would have other cost distribution effects. Although the allocation process is primarily a policy decision, there is one important role that science can playâdetermining when actions are âequivalent.â Water quality management actions are defined to be âequivalentâ when their implementation achieves the designated use, taking uncertainty into consideration. Note that there are two aspects of this definition of equivalency. First, equivalency is established with re- spect to ambient outcomes for the watershed and not in terms of pollutant loading comparisons, which is the way the allocations are described in the standard TMDL equation. Second, the definition recognizes that equivalency must account for the relative uncertainty of different actions with respect to meeting the applicable water quality standard. One common scenario might be the need to establish equivalency between nitrogen load reductions from a proposed agricultural BMP vs. a proposed wastewater treatment plant improvement. Estimates of the ef- fectiveness of the BMP and wastewater treatment technology can be made in a controlled setting, perhaps with field studies of the BMP and with experiments at the treatment plant. To achieve equivalency, these load reductions must have the same effect on meeting the water quality standard, which would normally be determined using a modeling ap- proach as described in Chapter 4. It is quite possible that the nitrogen load reductions at the sources (the agricultural BMP and the wastewater treatment plant) are different, but they are equivalent in that they are pre- dicted to have an identical effect on the standard. Further, as noted
Adaptive Implementation for Impaired Waters 99 above, equivalency is a function of both the forecasted mean and forecast uncertainty. Thus, if the BMP and wastewater treatment improvement are both forecast to have the same mean effect on the water quality stan- dard, but the wastewater treatment improvement response has less un- certainty, then the actions are not equivalent. Determining equivalency across sources requires predicting or meas- uring the results of control actions, rather than simply noting the pres- ence or absence of a particular control technology (the results of which may vary depending on how it is operated and on many other factors). Careful thought must be given to determining meaningful results, espe- cially in those watersheds where actions like flow augmentation or planting of oysters in an estuary are being used as substitutes for, or nec- essary complements to, load reduction to meet the designated use. Finally, because it should be focused on water quality outcomes, al- location is dependent on modeling the effects of different actions on wa- terbody response. Thus, the issues of model selection and uncertainty that were described in Chapter 4 for TMDL development also apply to TMDL allocation. If there is uncertainty about the effect of certain con- trol actions, those who bear the costs may resist taking such actions without further evidence of their worth. Adaptive implementation would support a cautious approach of taking low-cost actions with a high de- gree of certainty about the outcome, while taking parallel longer-term actions to improve model capabilities and revise control strategies. Progressing Toward Adaptive Implementation The TMDL program is limited by an incomplete conceptual understanding of waterbodies and watersheds, by models that are necessarily abstractions from the reality of natural systems, and by limited data for testing hypotheses and/or simulating systems. As a result, it is possible for a waterbody to be identified as impaired when it is not; in such cases, the costs to plan and implement control actions are wasted. On the other hand, it is also possible that an impaired waterbody will not be identified, resulting in other adverse consequences. Many of the stakeholders who addressed the committee expressed concern about the ramifications of uncertainty in the TMDL process. Some cautioned against listing errors, noting that the listing decision can trigger a linear and inflexible process of potentially expensive controls on land use and pollutant discharges that may ultimately prove unwarranted. Others who
100 Assessing the TMDL Approach to Water Quality Management are concerned that impaired waterbodies will go unidentified advocated more aggressive and comprehensive actions to address problems quickly. These differences in viewpoint can be traced to the policy context that now governs the TMDL program. The committee views adaptive implementation as accommodating this spectrum of opinions. If adaptive implementation is to be adopted, three policy issues that stand in the way of acceptance of the approach must be addressed. These issues are described without specific recommendations on their solution, except to note that their resolution is needed in order for the TMDL program to fully embrace the scientific method. Criticism of the TMDL program is too often, and sometimes inappropriately, directed at the quality of the data and information, rather than at these underlying policy issues. 1. The listing of a waterbody and the initiation of the TMDL process appear to call for a constraint on total pollutant loading associated with population growth and land use shifts until the designated use is obtained. Given the often weak water quality standards that underlie a listing, the long lag times between actions taken and measured responses, and the uncertainty in our ability to predict what actions will secure a designated use, it is unrealistic to expect that there will be no changes in economic activity and in land uses in a watershed until the designated use has been achieved. A basis for accommodating growth and change in watersheds needs to be established as adaptive implementation proceeds. 2. Many waterbody stressors currently lie outside the CWA regulatory framework, where the only federal enforcement tool available is point source discharge limits. Recognition of this fact was a motivation for EPAâs endorsement of the watershed approach in 1991 (EPA, 1993). Nonetheless, in some cases point source permitting is used to impose conditions on point sources that essentially require them to finance control practices for unregulated nonpoint sources (NAPA, 2000). Perceptions of the inequity and the ineffectiveness of such a requirement may be manifested as technical critiques of the TMDL analysis itself. Distributing the cost and regulatory burdens for designated use attainment in a way that is deemed equitable by all stakeholders is critical to future TMDL program success. 3. Watersheds can range in size from a few acres to an area that covers several states, and their diversity can be as far reaching as the diverse climate, soils, topography, and physiography of the entire United
Adaptive Implementation for Impaired Waters 101 States. Consequently, the approaches and solutions to water quality problems must be responsive to the unique characteristics of the surrounding watershed. EPA can set broad guidelines for each stateâs water quality program and can provide technical assistance in helping states meet the guidelines. There may be a leadership role for EPA on waterbodies that cross state boundaries, like the Chesapeake Bay. However, EPA cannot write and review all the designated uses that will apply to each of the nationâs waterbodies, it cannot conduct all the monitoring and make all the listing decisions, and it cannot conduct the model analyses for all waterbodies. The scientific foundation for adaptive implementation must rely on state initiative and leadership. Today, EPA retains an extensive oversight role for the TMDL program. This raises the possibility that in an effort to ease the administrative burdens of reviewing and approving every TMDL, EPA will establish requirements for uniformity. This may result in standard setting, listing/delisting, and modeling approaches that are nationally consistent but are scientifically inappropriate for the planning and decision-making needs of the diversity of waterbodies. In the National Pollution Discharge Elimination System (NPDES) permitting program, EPA has helped states assume responsibility for point source permitting such that EPA does not review every permit that is issued. Using similar logic, EPA need not review every TMDL. The concern that the states cannot be relied upon to take action (Houck, 1999) needs to be tempered by the reality that continued extensive EPA oversight may not be feasible, it may place a premium on developing plans instead of taking actions, and it may inhibit the nationâs progress toward improved water quality. The adaptive implementation approach may require increased state assumption of responsibility for individual TMDLs, with EPA oversight focused at the program level instead of on each individual water segment. Conclusions and Recommendations The call for adaptive implementation may not satisfy those who seek more definitive direction from the scientific community. Stakeholders and responsible agencies seek assurance that the actions they take will prove correct; they desire predictions of the costs and consequences of those actions in as precise terms as possible. However, waterbodies exist inside watersheds that are subject to constant change. For this reason
102 Assessing the TMDL Approach to Water Quality Management and others, even the best predictive capabilities of science cannot assure that an action leading to attainment of designated uses will be initially identified. Adaptive implementation will allow the TMDL program to move forward in the face of these uncertainties. 1. EPA should act (via an administrative rule) to incorporate the elements of adaptive implementation into TMDL guidelines and regulations. To increase the scientific foundation of the TMDL pro- gram, the scientific method, which is embodied by the adaptive imple- mentation approach, must be applied to water quality planning. 2. If Congress and EPA want to improve the scientific basis of the TMDL program, then the policy barriers that currently inhibit adoption of an adaptive implementation approach to the TMDL program should be addressed. This includes the issues of future growth, the equitable distribution of cost and responsibility among sources of pollution, and EPA oversight. REFERENCES Environmental Protection Agency (EPA). 1983. Technical Support Manual: Waterbody Surveys and Assessments for Conducting Use Attainability Analyses. Washington, DC: EPA Office of Water Regulations and Stan- dards. EPA. 1993. The Watershed Protection Approach, The Annual Report 1992. EPA 840-S-93-001. Washington, DC: EPA Office of Water. EPA. 1994. Water Quality Standards Handbook: Second Edition. EPA 823-B- 94-005a. Washington, DC: EPA Office of Water. Houck, O. A. 1999. The Clean Water Act TMDL Program: Law, Policy, and Implementation. Washington, DC: Environmental Law Institute. Novotny, V., J. Braden, D. White, A Capodaglio, R. Schonter, R. Larson, and K. Algozin. 1997. A Comprehensive UAA Technical Reference. 91-NPS-1. Alexandria, VA: Water Environment Research Foundation. National Academy of Public Administration. 2000. Transforming Environ- mental Protection for the 21st Century. Washington, DC: National Acad- emy of Public Administration. Page 86. Reckhow, K. H. 1985. Decision Theory Applied to Lake Management. In: Proceedings of the North American Lake Management Society Conference, p. 196â200. Robinson, A. R., and P. F. J. Lermusiaux. 2000. Overview of data assimilation. Harvard Reports in Physical/Interdisciplinary Ocean Science. Number 62. Cambridge, MA: Harvard University. 19p.