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Chesapeake Bay TMDL

Frequent Questions about the Chesapeake Bay TMDL

General Information and Background


What is a Total Maximum Daily Load (TMDL)?
What makes the Chesapeake Bay TMDL unique?
Why did EPA establish a TMDL for the Chesapeake Bay and its tidal tributaries?
What are the pollutants of concern and what are the sources of pollution?
What are the pollutant limits set by the Chesapeake Bay TMDL?
When was the Bay TMDL established and when does the TMDL anticipate the Bay will be restored?
There have been many TMDLs written in the Chesapeake Bay watershed. How do they relate to this Bay TMDL?
How large is the Chesapeake Bay? How big is the watershed that drains into it? How many people live within the watershed?


What is a Total Maximum Daily Load (TMDL)?

A Total Maximum Daily Load (TMDL) is a “pollution diet” that identifies the maximum amount of a pollutant a waterway can receive and still meet applicable water quality standards. A TMDL is the sum of wasteload allocations for point sources, load allocations for nonpoint sources, and a margin of safety to account for uncertainty. Point sources include sewage treatment plants, stormwater discharges, industrial discharges, etc. Nonpoint sources include pollutants carried by rainfall runoff from forests, agricultural lands, atmospheric deposition, abandoned land mines, etc.

TMDL = Wasteload Allocation + Load Allocation + Margin of Safety


What makes the Chesapeake Bay TMDL unique?

More than 40,000 TMDLs have been completed across the United States, but the Chesapeake Bay TMDL is the largest and most complex thus far. It is designed to achieve significant reductions in nitrogen, phosphorus and sediment throughout a 64,000-square-mile watershed that includes seven jurisdictions. Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia.

The TMDL is actually a combination of 276 nitrogen, phosphorus and sediment TMDLs for 92 individual Chesapeake Bay tidal segments. Pollution limits are designed to meet applicable water quality standards for dissolved oxygen, water clarity, underwater Bay grasses and chlorophyll-a, an indicator of algae levels.

The Chesapeake Bay TMDL is unique because of the extensive measures EPA and the jurisdictions adopted to ensure accountability for reducing pollution and meeting target progress dates. The TMDL will be implemented using an accountability framework that guides restoration efforts using four elements.  These elements include Watershed Implementation Plans (WIPs), two-year milestones, EPA’s tracking and assessment of restoration progress and specific federal actions if jurisdictions do not meet their commitments.

This accountability framework helps demonstrate the reasonable assurance provisions of the Bay TMDL pursuant to both the Clean Water Act and Chesapeake Bay Executive Order 13508. However, the accountability framework is not part of the Bay TMDL itself.


Why was a TMDL established for the Chesapeake Bay and its tidal tributaries?

Despite extensive restoration efforts over 25 years, the Bay TMDL was prompted by continued poor water quality in the Chesapeake Bay and its tidal tributaries. The TMDL is required under the Clean Water Act and responds to consent decrees in Virginia and the District of Columbia from the late 1990s. It is also a keystone commitment of a federal strategy to meet President Obama’s Executive Order 13508 to restore and protect the Bay.


What are the pollutants of concern and what are the sources of pollution?

Nitrogen, phosphorus, and sediment are the pollutants of concern. High levels of these pollutants enter the water from various sources, including agricultural operations, urban runoff, wastewater facilities, septic systems, air pollution, and other sources.


What are the pollutant limits set by the Chesapeake Bay TMDL?

The Bay TMDL set annual Bay watershed limits of 185.9 million pounds of nitrogen, 12.5 million pounds of phosphorus, and 6.45 billion pounds of sediment. That represents, based on 2009 levels, a 25 percent reduction in nitrogen, 24 percent reduction in phosphorus and 20 percent reduction in sediment. These limits are divided by state and river basin based on state-of-the-art modeling tools, extensive monitoring data, peer-reviewed science, and close interaction with Bay partners.


When was the Bay TMDL established and when does the TMDL anticipate the Bay will be restored?

The Bay TMDL was established on December 29, 2010. The TMDL is designed to ensure that all pollution control measures needed to fully restore the Bay and its tidal rivers are in place by 2025. EPA expects practices in place by 2017 to meet 60 percent of the necessary reductions.

While it will take years after 2025 for the Bay and its tributaries to fully heal, EPA expects some areas of the Bay will recover before others. There will be gradual and continued improvement in water quality as controls are put in place around the watershed.


There have been many TMDLs written in the Chesapeake Bay watershed. How do they relate to this Bay TMDL?

Previously-approved TMDLs were established to protect local waters. While some were based on reducing nitrogen, phosphorus, and sediment, many were for other pollutants. In contrast, the Bay TMDL is based on protecting the Bay and its tidal waters from excessive nitrogen, phosphorus, and sediment. For waters that have both local TMDLs and Bay TMDLs for nitrogen, phosphorus, and/or sediment, the more stringent of the TMDLs will apply.


How large is the Chesapeake Bay? How big is the watershed that drains into it? How many people live within the watershed?

Chesapeake Bay Watershed MapThe Bay itself is about 200 miles long, home to more than 3,700 species of plants, fish and other animals. The Bay watershed totals about 64,000 square miles, covering parts of six states and the District of Columbia. It stretches from Cooperstown, New York, to Norfolk, Virginia. Nearly 18 million people live in the watershed, and the population is growing by more than 130,000 each year. 

The map to the left shows the Chesapeake Bay watershed in green.

Developing the Bay TMDL


Who developed the Bay TMDL?
What factors were considered in developing the Bay TMDL?
What steps were involved in developing the Bay TMDL?
What were the principals involved in assigning pollution loadings?
How will federal agencies, including the EPA, contribute to the restoration effort?


Who developed the Bay TMDL?

EPA Region III’s Water Protection Division had primary responsibility for completion of the Bay TMDL. The region worked closely with modeling and water quality experts at the Chesapeake Bay Program Office. EPA Headquarters and EPA Region II also provided guidance and technical support. The Bay TMDL was co-signed by the Regional Administrators in Regions II and III since the Chesapeake Bay watershed spans both regions.

The Chesapeake Bay Program (CBP) partnership’s committee structure was used to engage the Bay jurisdictions in the development of the TMDL. The Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia, and the District of Columbia. Bay TMDL decisions were vetted through the CBP partnership’s Water Quality Goal Implementation Team, and major policy decisions were further reviewed by the Principals’ Staff Committee. When consensus could not be reached on key decision points, EPA was the final decision-maker.


What factors were considered in developing the Bay TMDL?

Development of the Chesapeake Bay TMDL required extensive knowledge of the watershed, sources of pollution, land uses, best management practices, precipitation data, and other factors.

The TMDL is informed by a series of models, calibrated to decades of water quality and other data, and refined based on input from Bay scientists. Modeling is an approach that uses observed and simulated data to replicate what is occurring in the environment to make future predictions. Modeling was a critical and valuable tool used to develop the Chesapeake Bay TMDL.


What steps were involved in developing the Bay TMDL?

The development of the TMDL consisted of several steps, including:

  1. EPA provided the jurisdictions with target loads for nitrogen, phosphorus and sediment at the basin-jurisdiction level. Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia.
  2. Jurisdictions developed Phase I Watershed Implementation Plans (WIPs) that detailed how they proposed to achieve those target loads. Jurisdictions made decisions on how to further sub-divide the basin-jurisdiction target loads to various individual point sources and point and nonpoint source sectors.
  3. EPA evaluated the Bay jurisdictions' draft Phase I WIPs. EPA used the jurisdictions' proposed allocations where they met their respective target loads and met EPA's expectations for reasonable assurance.  Where they did not, EPA supplemented gaps in allocations and reasonable assurance with allocation adjustments and determinations of reasonable assurance to achieve the necessary reductions.
  4. EPA published the draft TMDL on September 24, 2010 for a 45-day public comment period and held 18 public meetings in all seven jurisdictions.  EPA received, reviewed and considered tens of thousands of public comments for the final TMDL.  EPA's response to those public comments is Appendix W of the Chesapeake Bay TMDL.
  5. Working closely with EPA, the jurisdictions revised and strengthened their respective Phase I WIPs and submitted final Phase I WIPs to EPA.
  6. EPA evaluated the jurisdictions' final Phase I WIPs and used them, where possible, to develop the final TMDL.

What were the principals involved in assigning pollution loadings?

Nitrogen and phosphorus loads from all parts of the Bay watershed have an impact on the impaired tidal segments of the Bay and its rivers. Therefore, it was necessary for EPA to allocate the nitrogen and phosphorus loads in an equitable manner among the Bay states and major river basins.  EPA used three basic guides to divide these loads.

  1.  Allocated loads should protect living resources of the Bay and its tidal tributaries. Allocated loads should result in all segments of the Bay mainstem, tidal tributaries and embayments meeting applicable water quality standards. Those standards are for dissolved oxygen, chlorophyll a, water clarity and underwater Bay grasses.
  2.  Tributary basins that contribute the most to the Bay water quality problems should do the most to resolve those problems (on a pound per pound basis).
  3.  All tracked and reported reductions in nitrogen, phosphorus and sediment loads are credited toward achieving final assigned loads.
     

How will federal agencies, including the EPA, contribute to the restoration effort?

Federal agencies will contribute to the restoration of the Chesapeake Bay watershed through implementation of the federal strategy created under President Obama’s Executive Order 13508.  Eleven federal agencies have committed to a comprehensive suite of actions and pursuit of critical environmental goals on the same 2025 timeline as the TMDL. Additionally, federal agencies are setting two-year milestones, with the specific charge of taking actions that directly support the jurisdictions in restoring water quality.

Accountability


What assurances are there that the cleanup commitments will be met?
What if EPA determines that the Bay jurisdictions are not keeping pace with commitments?
How will EPA decide if federal actions are necessary?
 


What assurances are there that the cleanup commitments will be met?

The Chesapeake Bay TMDL is distinguished by the extensive measures EPA and the jurisdictions adopted to ensure accountability for reducing pollution and meeting target progress dates. The Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia.

The TMDL will be implemented using an accountability framework that guides restoration efforts using four elements. These elements include Watershed Implementation Plans (WIPs), two-year milestones, EPA tracking and assessment of progress and specific federal actions if jurisdictions do not meet their commitments. This accountability framework helps demonstrate the reasonable assurance provisions of the Bay TMDL pursuant to both the Clean Water Act and Chesapeake Bay Executive Order 13508. However, the accountability framework is not part of the Bay TMDL itself.


What if EPA determines that the Bay jurisdictions are not keeping pace with commitments?

The TMDL is designed to ensure that all pollution control measures needed to fully restore the Bay and its tidal rivers are in place by 2025. EPA expects practices in place by 2017 to meet 60 percent of the necessary reductions.

EPA’s goal is for the Bay jurisdictions to successfully implement their Watershed Implementation Plans (WIPs) and two-year milestones to achieve the necessary nutrient and sediment reductions.  Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia. 

EPA continually works with the jurisdictions to identify potential program improvements to help them get back on track and achieve the pollution reduction goals on schedule. If a Bay jurisdictions’ plans are inadequate or its progress is insufficient, EPA may take federal actions consistent with its December 29, 2009 letter to ensure pollution reductions.

Federal actions include expanding coverage of National Pollutant Discharge Elimination System (NPDES) permits to sources that are currently unregulated, increasing oversight of NPDES permits and requiring additional pollutant reductions from point sources. Other federal actions include increasing federal enforcement and compliance, prohibiting new or expanded discharges, redirecting EPA grants, and revising water quality standards to better protect local and downstream waters. All of these federal actions are based on existing EPA authority under the Clean Water Act.


How will EPA decide if federal actions are necessary?

Any federal actions will be guided by common sense, the best available information, and a shared goal to restore the Chesapeake Bay. EPA will consider all available information, including load reductions associated with pollutant controls and programmatic actions that Bay jurisdictions and local partners are taking to build capacity for future reductions. Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia.

EPA recognizes that the Chesapeake Bay Program (CBP) partnership will work to credit new practices, factor in new science, and account for previously under-reported implementation actions. EPA has discretion to determine whether federal actions are appropriate based on the degree to which reduction goals are missed and the reasons why. EPA will also consider additional actions taken by Bay jurisdictions to ensure load reductions will remain on track to meet the CBP partnership’s restoration goals.

 

Watershed Implementation Plans (WIPs)


What are Watershed Implementation Plans, or WIPs?
What do the Phase I WIPs do?
What do the Phase II WIPs do?
What is the primary purpose of the Phase III WIPs and when do you expect them to be submitted?


What are Watershed Implementation Plans, or WIPs?

The cornerstone of the accountability framework is the Bay jurisdictions’ development of Watershed Implementation Plans (WIPs). WIPs serve as roadmaps for how and when the Bay jurisdictions plan to meet their pollutant allocations under the TMDL. Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia.

There are two important criteria that EPA considers for each Bay jurisdictions' WIP. The first criteria for a WIP is that it achieves the Bay jurisdiction’s respective target loads at both the jurisdiction and major river-basin level.

The second criteria is that the WIP meets EPA's expectations for providing reasonable assurance that reductions will be achieved and maintained. Reasonable assurance provisions are particularly important for non-permitted sources like runoff from agricultural lands and currently unregulated stormwater from urban and suburban lands.


What do the Phase I WIPs do?

The Bay jurisdictions' Phase I WIPs subdivided target loads among pollutant sources and evaluated legal, regulatory, programmatic and financial tools available for implementation. Additionally, Phase I WIPs identified and rectified potential shortfalls in attaining the allocations, described mechanisms to track and report implementation activities, and provided alternative approaches Finally, Phase I WIPs outlined a schedule for implementation.


What do the Phase II WIPs do?

 

The primary purpose of the Phase II WIPs is to ensure that local partners are engaged and ready to help implement the WIPs. Local partners play a key role in restoring the Bay watershed.

On March 30, 2011, EPA released the Guide for Chesapeake Bay Jurisdictions for the Development of Phase II Watershed Implementation Plans. As articulated in this guide, Phase II provided Bay jurisdictions with the opportunity to facilitate implementation and refine their WIP strategies through local partner engagement. Although it varies by jurisdiction, “local partners” could include local governments, conservation districts, planning commissions, federal agencies, utilities, and watershed groups.

The most important element of the Phase II WIP is the narrative, which explains how Bay jurisdictions will work with key partners to meet restoration goals. Phase II WIPs were expected to ensure that all pollution control measures needed to fully restore the Bay and its tidal rivers are in place by 2025. EPA expects practices in place by 2017 to meet 60 percent of the necessary reductions between 2009 and 2025.

Bay jurisdictions' Phase II WIPs were expected to demonstrate that local partners have been engaged on WIP development and understand their contribution to meeting TMDL allocations.


What is the primary purpose of the Phase III WIPs and when do you expect them to be submitted?

EPA expects the Bay jurisdictions to submit Phase III WIPs in 2018, following a midpoint assessment of progress in 2017. Phase III WIPs should provide information on actions the Bay jurisdictions intend to implement between 2018 and 2025 to meet the Bay TMDL restoration goals.

The midpoint assessment of progress will include an update to the decision support tools used by the Chesapeake Bay Program partnership to develop implementation strategies. This update should aid the Bay jurisdictions in optimizing their Phase III WIPs.

Final TMDL & Next Steps


Where can I read the final Bay TMDL document?
How will EPA be monitoring progress by the Bay jurisdictions?
What are the next phases of the process?


Where can I read the final Bay TMDL document?

The final Bay TMDL document is available on our website.  View the Chesapeake Bay TMDL document.


How will EPA be monitoring progress by the Bay jurisdictions?

Under the accountability framework associated with the Chesapeake Bay TMDL, EPA committed to conduct ongoing oversight of programs within the Bay jurisdictions. Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia. EPA oversight will assure the Bay jurisdictions are on track to meet the goals of their Watershed Implementation Plans (WIPs) and two-year milestones.

EPA evaluates the milestone commitments that each jurisdiction makes every two years. In addition, EPA conducts, at a minimum, biennial reviews of the progress that each jurisdiction has made towards achieving the TMDL targets and milestone commitments.

EPA's goal is for the Bay jurisdictions to successfully implement their WIPs and two-year milestones to achieve the necessary nutrient and sediment reductions. However, EPA is prepared to take federal actions if it is necessary and appropriate to do so to help the jurisdictions reach their targets.

Federal actions are based on existing EPA authority under the Clean Water Act and can be taken at any time. Examples of federal actions include increasing and targeting federal enforcement and review of National Pollutant Discharge Elimination System (NPDES) permits and expanding permit coverage to unregulated sources.

In addition to EPA's on-going evaluations of WIPs and 2-year milestones, EPA conducts periodic reviews of state programs as part of its oversight responsibilities under the Clean Water Act. State programs reviewed include agriculture, stormwater, trading and offsets, etc. EPA works with the jurisdictions to make improvements to these programs.


What are the next phases of the process?

 

Currently, the Bay jurisdictions are actively engaged in the implementation of their respective Watershed Implementation Plans (WIPs) and two-year milestones. The Bay jurisdictions include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia. EPA is routinely conducting oversight of their progress towards meeting their two-year milestone and TMDL goals.

The Chesapeake Bay TMDL calls for an assessment in 2017 to review progress toward meeting the nutrient and sediment pollutant load reductions necessary for Bay restoration. EPA will assess the Bay jurisdictions’ progress towards meeting the 2017 goal of having practices in place to meet 60 percent of the necessary reductions compared to 2009 levels.

As part of this “midpoint assessment,” the Chesapeake Bay Program (CBP) partnership is reviewing the latest science, data, modeling and decision support tools used to measure progress. The intent of this part of the “midpoint assessment” is to strengthen the CBP partnership’s decision support capabilities to optimize the jurisdictions' Phase III WIPs.

In 2018, EPA expects the Bay jurisdictions to develop Phase III WIPs following a midpoint assessment of progress in 2017. The Phase III WIPs will provide information on actions the jurisdictions intend to implement between 2018 and 2025 to meet the Bay TMDL restoration goals.

The ultimate goal is to have all practices and controls installed by 2025 to achieve the Bay’s dissolved oxygen, water clarity/submerged aquatic vegetation and chlorophyll-a standards.

Litigation


Has the Chesapeake Bay TMDL been challenged in court?


Has the Chesapeake Bay TMDL been challenged in court?

On January 10, 2011, the American Farm Bureau Federation (AFBF) challenged EPA’s establishment of the Chesapeake Bay TMDL for nitrogen, phosphorus and sediment (American Farm Bureau Federation et al. v. EPA (M.D. Pa)). AFBF was soon joined by the National Association of Homebuilders and a variety of agricultural trade associations.

The Chesapeake Bay Foundation, other environmental groups, and trade associations representing municipal wastewater dischargers, among others, intervened on EPA’s side in defense of the TMDL. After submission of motions for summary judgment, the District Court heard five hours of oral argument on October 4, 2012.

On September 13, 2013, Judge Sylvia Rambo (U.S. District Court for the Middle District of Pennsylvania) dismissed in whole the challenge to EPA’s landmark Chesapeake Bay TMDL. In a wide-ranging decision, the court rejected all legal challenges, finding that the Chesapeake Bay TMDL and the framework established by the Chesapeake Bay Program Partnership in developing the cleanup plan was “consistent with” the CWA and other applicable federal laws.

The judge cited the “well documented” ecological and economic importance of the Chesapeake Bay, and held that the record in the case demonstrated the “extensive efforts on behalf of the Bay Partnership [between EPA and the Bay jurisdictions] to protect this important resource.” The court concluded that, in light of “the numerous complexities of regulating an interstate waterbody, EPA’s role is critical to coordinating the Bay Jurisdiction’s efforts to ensure pollution reduction.”

As a result of the court’s decision, the Chesapeake Bay TMDL remains in place to help guide continuing efforts to reduce nitrogen, phosphorus and sediment pollution to the Bay and its tidal tributaries. Read the September 13, 2013 Chesapeake Bay TMDL court decision.

By unanimous decision issued on July 6, 2015, the Third Circuit Court of Appeals found that EPA had acted within the scope of its authority under the Clean Water Act in establishing the TMDL for the Chesapeake Bay in 2010. In doing so, the court rejected the arguments by AFBF and others that the Bay TMDL could not legally include source allocations, target dates, and reasonable assurance.

The court determined that "[e]stablishing a comprehensive, watershed-wide TMDL - complete with allocations among different kinds of sources, a timetable, and reasonable assurance that it will actually be implemented - is reasonable and reflects a legitimate policy choice by the agency." The court's judgement affirmed the District Court decision dated September 13, 2013. Read the July 6, 2015 Chesapeake Bay TMDL court decision.

On February 29, 2016, the U.S. Supreme Court declined to review the decision of the Court of Appeals for the Third Circuit.  The AFBF (and other parties) had sought review and reversal of the Third Circuit decision of July 6, 2015 upholding EPA's establishment of the Chesapeake Bay TMDL.  By that denial, the Supreme Court ended five years of litigation regarding the Chesapeake Bay TMDL and allowed the Third Circuit ruling to stand as the final decision in the case.  View the docket for the case on the U.S. Supreme Court website.