Observations on Nutrient Management and the Chesapeake Bay TMDL

Transcription

1 Observations on Nutrient Management and the Chesapeake Bay TMDL Introduction William J. Rue and Sadie B. Barr EA Engineering, Science & Technology, Inc. 15 Loveton Circle, Sparks, MD On 29 December 2010, U.S. EPA published the final Chesapeake Bay TMDL to restore Bay water quality and the aquatic resources which make the region an invaluable recreational and economic resource. Popularly characterized as a pollution diet, the federally-mandated TMDL will add substantial wastewater treatment requirements to facilities located throughout watershed, will influence regional growth and development decisions, and will add substantially to the workload and budgets of federal, state and local regulatory agencies. The decades long efforts to get to this point have included: development and calibration of massive and sophisticated watershed models which address pollutant fate and transport, loading and runoff, and eutrophication; development of Bay-specific ambient water quality criteria for the protection of aquatic life (water clarity, dissolved oxygen, and chlorophyll-a); and loading scenarios to achieve water quality standards. All of these have been conducted in an open process which has allowed input by interested parties. The efforts to get to this point have been tremendous, and the efforts that will be required to achieve the Bay TMDL s goals will dwarf what has previously been done. The Bay TMDL is an historic effort; no other TMDL in the United States compares in terms of size, scope, and the amount of federal, state, and municipal coordination required to make it successful. As part of EPA s TMDL, each of the six states and the District of Columbia (D.C., DE, MD, NY, PA, VA, WV) that make up the 64,000 mi 2 watershed were required to develop detailed Watershed Implementation Plans (WIPs) which provided reasonable assurance that EPA s numeric and programmatic goals can and will be met. These substantial documents address: achieving EPA s nutrient and sediment target loads; future growth; tracking and reporting procedures to quantify progress; detailed tables which assign target loads to existing discharges; and a gap analysis. In essence, each state s WIP declares what is needed to accomplish the TMDL s targets, and details the regulatory programs and initiatives that will be used for implementation of the TMDL. Each state submitted their WIP to EPA, and then revised their WIP to reflect EPA s comments on deficiencies. EPA s final Bay TMDL and each of the seven WIPs can be found at: The goal of this paper is to present observations about the TMDL program based upon personal involvement, and interactions with other environmental and water quality professionals who have or will be influenced by the program. Unidentified Sources and Loads The agencies have identified numerous facilities with total nitrogen (TN), total phosphorus (TP) and total suspended solids (TSS) loads which discharge to the Bay watershed. Largely these listed facilities have NPDES discharge permits that contain monitoring requirements for one or more nitrogen or phosphorus components (most often only ammonia). Rarely, however, do these facilities have the required data to characterize their loadings for total nitrogen and phosphorus, and there is no reasonable correlation between ammonia and TN in wastewater discharges. This is a significant issue, as many facilities are 1

2 going into this TMDL process without knowing what their TN and TP loadings are for existing operations, and with limited time to generate adequate data to quantify these loads and assess expected variability. In addition, there are many other facilities which have nutrient loadings that are not assigned individual load allocations, and are instead included in what is called an aggregate load within each subwatershed. Often these are facilities that have never had to monitor TN or TP, or their processes are generally believed to not result in nutrient discharges. From the agencies perspective, the aggregate load approach is good, as it allows them to simply assign a load to subwatersheds which can be shared and does not require the discharge flow and concentration data necessary to assign load estimates to numerous smaller and relatively insignificant facilities. We are aware, however, that there are a number of existing facilities where the loadings for a single facility are known to exceed the assigned aggregate load for that particular subwatershed. This will need to be addressed, and an actual load should be assigned without considering these existing facilities to be a new load, which would require nutrient offsets. Hopefully this can happen during the Phase 2 WIP process. Variable Loadings Some industrial and municipal operations do not discharge consistent flows and concentrations, their loadings are quite variable, and they cannot predict what their future loadings will be. Classic examples in Maryland are the Dredged Material Containment Facilities (DMCFs) such as Cox Creek and Masonville. These facilities receive dredged material from Baltimore Harbor, dewater that material within large basins, and then discharge the supernatant to surface waters via NPDES permits. The difficulties within the new TMDL system is that these facilities cannot know how much material they will receive from year to year, which channels those materials will come from (degree of TN and TP contamination), and therefore what their loadings will be in future years. In some years, therefore, these DMCFs may be substantially below their assigned load allocations, and in other years necessary channel dredging may cause the facilities to exceed their permitted loads. Will these occasional TN and TP loading exceedences result in permit violations? And if offsets will be required for these occasional high volume years, how will they reasonably be able to predict, obtain credits for the two permit cycle requirement (10 years), and pay for the future offset requirements (from state funds)? Another interesting concept regarding the DMCFs is that the TN and TP loadings they discharge to Baltimore Harbor, via their NPDES permits, originated from Baltimore Harbor itself. Although in concept this is simply a recycling of nutrients within the same estuarine system, the facilities still require load allocations and are expected to have to pay for nutrient credits. This seems inequitable since the DMCFs are reducing the TN and TP loadings substantially from what is originally removed from the Harbor. Such discrepancies will hopefully be addressed as the Bay TMDL and state WIPs moves forward into Phase 2 during the coming year. TMDL Program Costs In the State s WIP transmittal letter to EPA, Maryland stated that preliminary cost estimates to the State for the period 2011 through 2017 could be as high as $10 billion, and indicated that the Federal government should assist state and local governments to meet the Bay TMDL commitments. In developing the Bay TMDL, EPA has stated that although they are required by law to establish the TMDL and the loadings necessary to meet water quality standards, they are not required to establish funding or sources of funding. Given this, the EPA s TMDL document does not consider costs for the implementation of TMDL load targets. EPA recognizes that funding to municipalities and states is 2

3 relevant to the implementation of the TMDL (e.g., for infrastructure upgrades for MS4 sewer systems), but specifically notes that it is beyond the scope of the TMDL itself. That said, the EPA is funding costshare, grant, and technical assistance programs to assist the Bay community in implementing TMDL strategies. For example, there has been an $11.2 million increase in Chesapeake Bay funding, now totaling $50 million; this money should be allocated to the affected Bay watershed jurisdictions to develop new regulations, design WIPs, reissue/enforce permits, etc. In addition, in the President s FY 2011 Budget, the Bay jurisdictions are scheduled to receive $155 million under the Clean Water State Revolving Loan Fund (CW SRF), and further funding should be available through grant programs under the Clean Water Act (CWA 106 and CWA 319). EPA has not stated whether these funding sources will be sufficient to execute all of the Bay TMDL s initiatives, but given Maryland s preliminary cost estimate (and considering that Maryland is only one of the seven jurisdictions in need of funding), it is anticipated that these monetary issues will persist throughout the implementation period of the TMDL. Additionally, it brings up the crucial issue of whether corporations will be able to afford costly water quality improvements given the current economic climate, or perhaps shift marginal operations to a different part of the country. Maryland has put a major emphasis on improving the quality of wastewaters discharged by the 66 major municipal wastewater treatment plants, and is making significant progress via Enhanced Nutrient Removal (ENR) upgrades. ENR results in substantial TN and TP loading reductions. Through 2010, upgrades to 10 facilities have been completed and are in operation. Upgrades to 10 other facilities are under construction, 25 are in the design phase, and 14 are in planning. MDE is working to bring the remaining seven major systems into the ENR program. In the June 2010 Bay Restoration Funding Status Report by MDE, wastewater treatment plant construction costs in recently opened bids were significantly higher than the original pre-planning level estimates. As a result the total capital cost for the ENR Upgrades in Maryland is likely to be higher than the $750 million to $1 billion range estimated at the time the legislation was passed. Unfortunately, the current ENR capital cost is estimated at $1.54 billion leaving a potential deficit of $660 million. This funding gap is expected to begin in In the current political and economic climate, and the ever increasing need to prioritize essential budget issues, there are reasonable questions whether the Bay watershed states, counties, municipalities, and private businesses will be able to fund the necessary water quality improvement programs that they are being required to make within the identified timeframes. Modeling Because the Chesapeake Bay mainstem and its watershed are so large and intricate, scientists must rely on complex computer models for critical information about the ecosystem s characteristics, and to predict the impact of various environmental actions to reduce pollution (management scenarios). The Chesapeake Bay TMDL is the largest and most complex ever initiated by EPA or the states. The Bay TMDL is actually the result of a suite of models, calibrated to decades of Bay-wide data, with the goal of determining how various loadings of TN, TP and TSS can be managed within small spatial scales to achieve state water quality standards for dissolved oxygen, water clarity, and chlorophyll-a. These models, which have been developed and refined over 30 years (and will continue to be refined throughout the TMDL implementation period), include: 1. Bay Watershed Model which divides the Chesapeake Bay watershed into more than 2,000 segments delineating political and physical boundaries and incorporates information about land use, fertilizer applications, wastewater plant discharges, septic systems, air deposition, farm 3

4 animal populations, weather and other variables to estimate the amount of nutrients and sediment reaching the Chesapeake Bay and where these pollutants originate. The current version (Phase 5.3) replaces Phase 4.3, and has many important improvements over previous versions, such as the inclusion of an extended network of calibration sites and watersheds. 2. The Estuary Model which examines the effects that nutrient loads generated by the Watershed Model have on water quality (includes more than 57,000 computational cells) 3. Airshed Model which uses information about nitrogen emissions from power plants, vehicles and other sources to estimate the amount of and location where these pollutants are deposited on the Chesapeake Bay and its watershed. 4. Land Change Model which analyzes and forecasts the effects of urban land use and population changes on sewer and septic systems in the Bay watershed. 5. Scenario Builder which generates simulations of the past, present or future state of the Chesapeake Bay watershed to evaluate potential impacts of alternate management actions and alternatives. Two points to be made here are that although the model systems that have been developed are among the most sophisticated in the world, and have been calibrated based on extensive historic datasets, their accuracy in predicting load allocations for individual Bay subwatersheds should not be overstated. As noted by EPA, although model simulations are an important part of the Chesapeake Bay restoration effort, they are not considered to be perfect forecasts. Rather, model simulations are best estimates based on state-of-the-art, extensively peer-reviewed science. Modeling is part of a broader toolkit that includes research and monitoring to gain the highest possible level of accuracy 1. Secondly, we suggest that because the resulting modeled load allocations do have a degree of uncertainty associated with them, resulting load-based permit limitations should be interpreted and applied in a manner that is consistent with this fact. Nutrient Trading Maryland s Department of Agriculture and Department of the Environment have developed requirements and procedures which will allow dischargers to obtain nutrient credits where they are needed to comply with load-based permit limitations. However, the nutrient trading system is still in its infancy, and there is uncertainty as to whether State-approved credits will be available when they are needed, and if enough credits currently exist. As discussed above, some facilities will not know how many pounds of TN or TP will be required for each of the ten years that dischargers are required to acquire offsets leading to purchases. In addition, another lingering issue is the uncertainty of marketbased costs of TN and TP credits ($/pound/year), which is important when trying to budget for future costs that are anticipated to be quite significant. Total Sediments (Total Suspended Solids [TSS]) and Stormwater Management Although total sediment loads (TSS) are not as developed as TN and TP allocations, they are in no way an insignificant part of the Bay TMDL. For example, from now until 2025, the EPA TMDL is requiring a 20 percent reduction in TSS, which is comparable with the 25 percent reduction in TN and 24 percent reduction in TP. A major contributor to TSS (and nutrients) in the Chesapeake Bay watershed is point and non-point source stormwater runoff, which can be much more difficult to model and assess than nutrient discharges. Initial controls for TSS in Maryland will be included in new MS4 NPDES permits, 1 Source: 4

5 which will require large municipalities and some agencies (e.g., Montgomery County, Maryland SHA) to increase their management of impervious surfaces from approximately 10 to 30 percent. This will require a substantial increase in the use of Best Management Practices (BMPs), and will demand extensive stormwater management upgrades, all of which will impact state and municipal budgets. Although TN and TP modeling efforts are currently farther along than TSS, it is still an important part of the Bay TMDL. The capabilities to model and predict TSS discharges will likely be refined during the Phase 2 process, and regulatory controls for TSS have and will be enforced just as they are planned for TN and TP. Final Thoughts The agencies need to allow flexibility within the program to deal with the uncertainties that exist with many aspects of this massive and innovative Bay-wide TMDL program. This flexibility could involve changing load allocations to better reflect what facilities actually discharge (versus modeled loads, or loads determined where concentrations of TN and TP are not known). This flexibility could also include more time for meeting certain Bay TMDL deadlines when facilities or municipalities cannot afford to implement certain required improvements. The phase 2 WIP program, which occurs in 2011, is a critical step within the TMDL program which will allow the states to make corrections to their programs to ensure that existing dischargers are treated fairly and equitably, and that facilities with current loadings are never characterized as new sources requiring complete offsets. This is especially important since many of the models used to develop the Chesapeake Bay TMDL are continually being refined, and may yield varying results from previous versions that are the basis of current watershed loads. In addition, the Phase 2 process will allow state regulators to further evaluate nutrient driven watershed permits, and determine which discharges are significant enough to warrant individual allocations.we have been involved with several new NPDES permits where 90 percent reductions of TN will be required, yet the facility s operations are not consistent with ENR technology upon which the permit limit is based. There should be some flexibility to allow facilities in this type of situation to support alternate permits limits, or more time to comply with new loading permit limits. It will be critical for facilities and municipalities to carefully account for load-reductions that are achieved. This will be particularly important (and challenging) for counties and other municipal groups, since there are so many activities that are conducted by different departments which reduce loadings to surface waters (wastewater treatment plant improvements, stormwater management improvements, street sweeping, watershed restoration projects, etc). Quantifying these load reductions will be important for permittees as well as the states and EPA. Overall, the Bay TMDL will require extensive efforts by regulators and the broader regulated community to meet the load reductions envisioned by the program. It will be important to implement the program carefully, and to monitor the beneficial results to determine whether the massive expenditures have their predicted benefits. 5