# Chesapeake Bay Total Maximum Daily Load for Nitrogen, Phosphorus and Sediment

December 29, 2010

U.S. Environmental Protection Agency Region 3 Water Protection Division

Air Protection Division Office of Regional Counsel Philadelphia, Pennsylvania

U.S. Environmental Protection Agency Region 3 Chesapeake Bay Program Office Annapolis, Maryland

and

U.S. Environmental Protection Agency Region 2 Division of Environmenta l Planning and Protection New York, New York

in coordination with

U.S. Environmental Protection Agency Office of Water Office of Air and Radiation Office of General Counsel Office of the Administrator Washington, D.C.

and in collaboration with

Delaware, the District of Columbia, Maryland, New York, Pennsylvania, Virginia, and West VirginiaChesapeake Bay TMDL



## CHESAPEAKE BAY TMDL EXECUTIVE SUMMARY

INTRODUCTION The U.S. Environmental Protection Agency (E PA) has established the Chesapeake Bay Total Maximum Daily Load (TMDL), a historic and comprehensive “pollution diet” with rigorous accountability measures to initiate sweeping actions to restore clean water in the Chesapeake Bay and the region’s stre ams, creeks and rivers.

Despite extensive restoration efforts during the past 25 year s, the TMDL was prompted by insufficient progress and conti nued poor water quality in th e Chesapeake Bay and its tidal tributaries. The TMDL is requ ired under the federal Clean Wa ter Act and responds to consent decrees in Virginia and the District of Columb ia from the late 1990s. It is also a keystone commitment of a federal strategy to meet Pres ident Barack Obama’s Executive Order to restore and protect the Bay.

The TMDL – the largest ever developed by EPA – identifies the necessary pollution reductions of nitrogen, phosphorus and sediment across De laware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia and sets pollution limits necessary to meet applicable water quality standard s in the Bay and its tidal rive rs and embayments. Specifically, the TMDL sets Bay watershed limits of 185.9 million pounds of nitrogen, 12.5 million pounds of phosphorus and 6.45 billion pounds of sediment per year – a 25 pe rcent reduction in nitrogen, 24 percent reduction in phosphorus and 20 percent reduction in sediment. These pollution limits are further divided by jurisdiction and major river basin based on state-of-the-art modeling tools, extensive monitoring data, peer-rev iewed science and close interac tion with jurisdiction partners.

The TMDL is designed to ensure that all pollution cont rol measures needed to fully restore the Bay and its tidal rivers are in place by 2025, with at least 60 per cent of the actions completed by 2017. The TMDL is supported by rigorous accountability measures to ensure cleanup commitments are met, including short-and long- term benchmarks, a tracking and accountability system for jurisdiction activities, and federal contingency actions that can be employed if necessary to spur progress.
Watershed Implementation Plans (WIPs), which deta il how and when the six Bay states and the District of Columbia will meet pollution allocatio ns, played a central role in shaping the TMDL. Most of the draft WIPs subm itted by the jurisdictions in September 2010 did not sufficiently identify programs needed to reduce pollution or provide assurance the programs could be implemented. As a result, the draft TMDL issued September 24, 2010 contained moderate- to high-level backstop measures to tighten cont rols on federally permitted point sources of pollution.

A 45-day public comment period on the draft TMDL was held from September 24 to November 8, 2010. During that time, EPA held 18 public meeti ngs in all seven Bay watershed jurisdictions, which were attended by about 2,500 citizens. EPA received more than 14,000 public comments and, where appropriate, incorpor ated responses to those comme nts in developing the final TMDL.

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After states submitted the draft WIPs, EPA worked closely with each jurisdiction to revise and strengthen its plan. Because of this cooperative work and state leadership, the final WIPs were significantly improved. Examples of specific improvements include:

 Regulated point sources and non-regulated nonpoint sources of nitrogen, phosphorus, and sediment are fully considered and evaluate d separately in terms of their relative contributions to water quality impairment of the Chesapeake Bay’s tidal waters.

 Committing to more stringent nitrogen and phosphorus limits at wastewater treatment plants, including on the James River in Vi rginia. (Virginia, New York, Delaware)

 Pursuing state legislation to fund wastewater treatment plant upgrades, urban stormwater management and agricultural programs . (Maryland, Virginia, West Virginia)

 Implementing a progressive stormwater permit to reduce pollution. (Dis trict of Columbia)

 Dramatically increasing enforcement and complia nce of state requirements for agriculture. (Pennsylvania)

 Committing state funding to develop and impl ement state-of-the-art-technologies for converting animal manure to ener gy for farms. (Pennsylvania)

 Considering implementation of mandatory pr ograms for agriculture by 2013 if pollution reductions fall behind schedule. (Delaware, Maryland, Virginia)

These improvements enabled EPA to reduce and remove most federal backstops, leaving a few targeted backstops and a plan for enhanced oversi ght and contingency actions to ensure progress. As a result, the final TMDL is shaped in large part by the jurisdictions’ plans to reduce pollution, which was a long-standing priority for EPA and why the agency always provided the jurisdictions with flexibility to determine how to reduce pollution in the most efficient, costeffective and acceptable manner.

Now the focus shifts to the jurisdictions’ implementation of the WIP policies and programs that will reduce pollution on-the-ground and in-the -water. EPA will conduct oversight of WIP implementation and jurisdictions’ progress toward meeting two-year milestones. If progress is insufficient, EPA is committed to take appropriate contingency actions including targeted compliance and enforcement activities, expans ion of requirements to obtain NPDES permit coverage for currently unregulated sources, revision of the TMDL allocations and additional controls on federally permitted sources of polluti on, such as wastewater treatment plants, large animal agriculture operations and municipal stormwater systems.

In 2011, while the jurisdictions continue to impl ement their WIPs, they will begin development of Phase II WIPs, designed to engage local gove rnments, watershed organizations, conservation districts, citizens and other key stak eholders in reduc ing water pollution.



### TMDL BACKGROUND The Clean Water Act (CWA) sets an overarching environmental goal that all waters of the United States be “fishable” and “swimmable.” More sp ecifically it requires states and the District of Columbia to establish appropria te uses for their waters and a dopt water quality standards that are protective of those uses. The CWA also require s that every two years jurisdictions develop – with EPA approval – a list of waterways that are impaired by pollutants and do not meet water

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quality standards. For those waterways identi fied on the impaired list, a TMDL must be developed. A TMDL is essentially a “pollution diet” that identifies the maximum amount of a pollutant the waterway can receive a nd still meet water quality standards.

Most of the Chesapeake Bay and its tidal wate rs are listed as impaired because of excess nitrogen, phosphorus and sediment. These pollutants cause algae blooms that consume oxygen and create “dead zones” where fish and shellfish ca nnot survive, block sunli ght that is needed for underwater Bay grasses, and smot her aquatic life on the bottom. The high levels of nitrogen, phosphorus and sediment enter the water from agricultural operations, urban and suburban stormwater runoff, wastewater f acilities, air pollution and other sources, including onsite septic systems. Despite some reductions in pollution du ring the past 25 years of restoration due to efforts by federal, state and local gover nments; non-governmental organizations; and stakeholders in the agriculture, urban/suburban stormwater, and wastewat er sectors, there has been insufficient progress toward meeting the wa ter quality goals for the Chesapeake Bay and its tidal waters.

More than 40,000 TMDLs have been completed across the United States, but the Chesapeake Bay TMDL will be the largest and most complex t hus far – it is designed to achieve significant reductions in nitrogen, phosphorus and sedi ment pollution throughout a 64,000-square-mile watershed that includes the Distri ct of Columbia and large secti ons of six states. The TMDL is actually a combination of 92 smaller TMDLs for individual Chesapeake Bay tidal segments and includes pollution limits that are sufficient to m eet state water quality standards for dissolved oxygen, water clarity, underwater Bay grasses and chlorophyll- a , an indicator of algae levels (Figure ES-1). It is important to note that th e pollution controls employed to meet the TMDL will also have significant benefits for water quality in tens of thous ands of streams, creeks, lakes and rivers throughout the region.

Since 2000, the seven jurisdictions in the Chesap eake Bay watershed (Del aware, District of Columbia, Maryland, New York, Pennsylvania, Vi rginia, and West Virginia), EPA and the Chesapeake Bay Commission, which are partners in the Chesapeake Bay Program, have been planning for a Chesapeake Bay TMDL.

Since September 2005, the seven jurisdictions have b een actively involved in decision-making to develop the TMDL. During the October 2007 me eting of the Chesapeake Bay Program’s Principals’ Staff Committee, the Bay watershed jurisdictions and EPA agreed that EPA would establish the multi-state TMDL. Since 2008, EPA has sent official letters to the jurisdictions detailing all facets of the TM DL, including: nitrogen, phosphorus and sediment allocations; schedules for developing the TMDL and pollu tion reduction plans; EP A’s expectations and evaluation criteria for jurisdiction plans to meet the TMDL pollution limits; reasonable assurance for controlling nonpoint source pollu tion; and backstop actions that EPA could take to ensure
progress.

The TMDL also resolves commitments made in a number of consent decrees, Memos of Understanding, the Chesapeake Bay Foundation se ttlement agreement of 2010, and settlement agreements dating back to the late 1990s that address certain tidal waters identified as impaired in the District of Columbia, Delaware, Maryland and Virginia.

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Figure ES-1. A nitrogen, phosphorus and sediment TMDL has been devel oped for each of the 92 Chesapeake Bay segment watersheds.
Additionally, President Obama issued Executive Order 13508 on May 12, 2009, which directed the federal government to lead a renewed effort to restore and protect the Chesapeake Bay and its watershed. The Chesapeake Bay TMDL is a keystone commitment in the strategy developed by 11 federal agencies to meet the President’s Executive Order.

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### DEVELOPING THE CH ESAPEAKE BAY TMDL Development of the Chesapeake Bay TMDL requi red extensive knowledge of the stream flow characteristics of the watershed, sources of pollu tion, distribution and acre age of the various land uses, appropriate best management practices, the transport and fate of pollutants, precipitation data and many other factors. The TMDL is inform ed by a series of models , calibrated to decades of water quality and other data, and refined based on input from dozens of Chesapeake Bay scientists. Modeling is an approach that uses observed and si mulated data to replicate what is occurring in the environment to make future pred ictions, and was a critical and valuable tool to develop the Chesapeake Bay TMDL.

The development of the TMDL consisted of several steps:
1. EPA provided the jurisdictions with loadi ng allocations for nitrogen, phosphorus and sediment for the major rive r basins by jurisdiction.
2. Jurisdictions developed draft Phase I WIPs to achieve those basin-jurisdiction allocations. In those draft WIPs, jurisdictions made d ecisions on how to further sub-allocate the basin-jurisdiction loadings to various indivi dual point sources and a number of point and nonpoint source pollution sectors.
3. EPA evaluated the draft WIPs and, where de ficiencies existed, EPA provided backstop allocations in the draft TMDL that cons isted of a hybrid of the jurisdiction WIP allocations modified by EPA allocations for some source sectors to fill gaps in the WIPs.
4. The draft TMDL was published for a 45-day public comment period and EPA held 18 public meetings in all six states and the Di strict of Columbia. Public comments were received, reviewed and cons idered for the final TMDL.

5. Jurisdictions, working closely with EPA, re vised and strengthened Phase I WIPs and submitted final versions to EPA.
6. EPA evaluated the final WIPs and used them along with public comments to develop the final TMDL.

Since nitrogen and phosphorus load ings from all parts of the Ba y watershed have an impact on the impaired tidal segments of the Bay and its rivers, it was necessary for EPA to allocate the nitrogen and phosphorus loadings in an equitable manner to the states and basins. EPA used three basic guides to divide these loads.

 Allocated loads should protect living resource s of the Bay and its tidal tributaries and should result in all segments of the Bay mainstem, tidal tributaries and embayments meeting water quality standards for dissolved oxygen, chlorophyll a , water clarity and underwater Bay grasses.

 Tributary basins that contribute the most to the Bay water quality problems must do the most to resolve those problems (on a pound-per-pound basis) (Figure ES-2).

 All tracked and reported reductions in nitroge n, phosphorus and sediment loads are credited toward achieving final assigned loads.

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Figure ES-2. Sub-basins across the Chesapeake Bay watershed with the highest (red) to lowest (blue) pound for pound nitrogen pollutant loading effect on Chesapeake Bay water quality.

In addition, EPA has committed to reducing air depos ition of nitrogen to the tidal waters of the Chesapeake Bay from 17.9 to 15.7 million pounds pe r year. The reductions will be achieved through implementation of federal air regulations during the coming years.

To ensure that these pollutant loadings will attain and maintain applicable water quality standards, the TMDL calculations were deve loped to account for critical environmental conditions a waterway would face and seasonal va riation. An implicit margin of safety for nitrogen and phosphorus, and an explicit margin of safety for sediment, also are included in the TMDL.

Ultimately, the TMDL is designed to ensure that by 2025 all practices necessary to fully restore the Bay and its tidal waters are in place, with at least 60 percent of the actions taken by 2017.

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The TMDL loadings to the basin-jurisdictions ar e provided in Table ES- 1. These loadings were determined using the best peer-reviewed scie nce and through extensive collaboration with the jurisdictions and are informed by the jurisdictions’ Phase I WIPs.

Table ES-1. Chesapeake Bay TMDL watershed nitrogen, phosphorus and sediment final allocations by jurisdiction and by major river basin. Nitrogen allocations Phosphorus allocations Sediment allocations Jurisdiction Basin (million lbs/year) (million lb s/year) (million lbs/year) Susquehanna 68.90 2.49 1,741.17
Potomac 4.72 0.42 221.11 Eastern Shore 0.28 0.01 21.14
Western Shore 0.02 0.00 0.37 Pennsylvania

PA Total 73.93 2.93 1,983.78 Susquehanna 1.09 0.05 62.84
Eastern Shore 9.71 1.02 168.85
Western Shore 9.04 0.51 199.82
Patuxent 2.86 0.24 106.30
Potomac 16.38 0.90 680.29 Maryland

MD Total 39.09 2.72 1,218.10 Eastern Shore 1.31 0.14 11.31
Potomac 17.77 1.41 829.53 Rappahannock 5.84 0.90 700.04
York 5.41 0.54 117.80
James 23.09 2.37 920.23 Virginia

VA Total 53.42 5.36 2,578.90
Potomac 2.32 0.12 11.16 District of Columbia DC Total 2.32 0.12 11.16 Susquehanna 8.77 0.57 292.96 New York
NY Total 8.77 0.57 292.96 Eastern Shore 2.95 0.26 57.82 Delaware
DE Total 2.95 0.26 57.82
Potomac 5.43 0.58 294.24
James 0.02 0.01 16.65 West Virginia

WV Total 5.45 0.59 310.88
Total Basin/Jurisdiction Draft Allocation 185.93 12.54 6,453.61

Atmospheric Deposition Draft Allocationa 15.7 N/A N/A

Total Basinwide Draft Allocation 201.63 12.54 6,453.61

a Cap on atmospheric deposition loads direct to Chesap eake Bay and tidal tributary surface waters to be achieved

by federal air regulations through 2020.

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### ACCOUNTABILITY AND GOALS The Chesapeake Bay TMDL is unique because of the extensive measures EPA and the jurisdictions have adopted to ensure accountability for reduci ng pollution and meeting deadlines for progress. The TMDL will be implemented us ing an accountability framework that includes WIPs, two-year milestones, EPA’s tracking and assessment of restoration progress and, as necessary, specific federal contingency actions if the jurisdictions do not meet their commitments. This accountability framework is being established in part to provide demonstration of the reasonable assurance provi sions of the Chesapeake Bay TMDL pursuant to both the Clean Water Act (CWA) and the Chesapeake Bay Executive Order, but is not part of the TMDL itself.

When EPA establishes or approv es a TMDL that allocates pollu tant loads to both point and nonpoint sources, it determines whether there is a “reasonable assurance” that the point and nonpoint source loadings will be achieved and appl icable water quality standards will be attained. Reasonable assurance for the Chesapeake Bay TMDL is provided by the numerous federal, state and local regulatory and non-regulatory programs identified in the accountability framework that EPA believes will result in the necessary point and nonpoint source c ontrols and pollutant reduction programs. The most prominent program is the CWA’s Nationa l Pollutant Discharge Elimination System (NPDES) permit program that regulates point source s throughout the nation. Many nonpoint sources are not covered by a simila r federal permit program; as a result, financial incentives, other voluntary programs and state-sp ecific regulatory programs are used to achieve nonpoint source reductions. These fe deral tools are supplemented by a variety of state and local regulatory and voluntary programs and other commit ments of the federal government set forth in the Executive Order strategy and identif ied in the accountability framework.

Beginning in 2012, jurisdictions (including the fede ral government) are expected to follow twoyear milestones to track progress toward reach ing the TMDL’s goals. In addition, the milestones will demonstrate the effectiveness of the jurisd ictions’ WIPs by identifying specific near-term pollutant reduction controls and a schedule fo r implementation (see next section for further description of WIPs). EPA will review these two- year milestones and evaluate whether they are sufficient to achieve necessary pollution re ductions and, through the use of a Bay TMDL Tracking and Accountability System, determine if milestones are met.

If a jurisdiction’s plans are inadequate or its progress is insufficient, EPA is committed to take the appropriate contingency act ions to ensure pollution reduc tions. These include expanding coverage of NPDES permits to sources that ar e currently unregulated, increasing oversight of state-issued NPDES permits, requiring additional po llution reductions from point sources such as wastewater treatment plants, increasing federa l enforcement and compliance in the watershed, prohibiting new or expanded pollu tion discharges, redirecting EP A grants, and revising water quality standards to better prot ect local and downstream waters.



### Watershed Implementation Plans The cornerstone of the accountability framewor k is the jurisdictions’ development of WIPs, which serve as roadmaps for how and when a juri sdiction plans to meet its pollutant allocations under the TMDL. In their Phase I WIPs, the jurisd ictions were expected to subdivide the Bay TMDL allocations among pollutant sources; evaluate their current legal, regulatory,

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programmatic and financial tools available to im plement the allocations; identify and rectify potential shortfalls in attaining the allocati ons; describe mechanisms to track and report implementation activities; provide alterna tive approaches; and outline a schedule for implementation.

EPA provided the jurisdictions with detailed expectations for WIPs in November 2009 and evaluation criteria in April 2010. To assist with WIP prepara tion, EPA provided considerable technical and financial assistance. EPA worked w ith the jurisdictions to evaluate various “what if” scenarios – combinations of practices and programs that could achieve their pollution allocations.

The two most important criteria for a WIP is that it achieves the basin-jurisdiction pollution allocations and meets EPA’s expectations for prov iding reasonable assurance that reductions will be achieved and maintained, particularly for non- permitted sources like runoff from agricultural lands and currently unregul ated stormwater from urban and suburban lands.

After the draft Phase I WIP submittals in Se ptember 2010, a team of EPA sector experts conducted an intense evaluation process, compari ng the submissions with EPA expectations. The EPA evaluation concluded that the pollution controls identified in two of the seven jurisdictions’ draft WIPs could meet nitrogen and phosphorus al locations and five of the seven jurisdictions’ draft WIPs could meet sediment allocations. The EPA evaluation also conc luded that none of the seven draft Phase I WIPs provided sufficient reasonable assurance that pollution controls identified could actually be implemented to achieve the nitrogen, phosphorus and sediment reduction targets by 2017 or 2025.

In response to its findings, EPA developed a dr aft TMDL that established allocations based on using the adequate porti ons of the jurisdictions’ draft WIP a llocations along with varying degrees of federal backstop allocations in all seven jurisdictions. Back stop allocations focused on areas where EPA has the federal authority to contro l pollution allocations through NPDES permits, including wastewater treatment plants, stormwater permits, and animal feeding operations.



### Public Participation The draft Chesapeake Bay TMDL was develope d through a highly transparent and engaging process during the past two years. The outreach effort included hundred s of meetings with interested groups; two rounds of public meetings, stakeholder sessi ons and media interviews in all six states and the District of Columbia in fall of 2009 and 2010; a dedicated EPA website; a series of monthly interactive we binars; notices published in th e Federal Register; and a close working relationship with Chesapeake Bay Program committees representing citizens, local governments and the scientific community.

The release of the draft Ch esapeake Bay TMDL on September 24, 2010 began a 45-day public comment period that concluded on Novemb er 8, 2010. During the comment period EPA conducted 18 public meetings in all six states and the District of Columbia. More than 2,500 people participated in the public meetings. Seve n of these meetings were also broadcast live online. During the six weeks that EPA officials traveled around the watershed, they also held dozens of meetings with stakeholders, incl uding local governments, agriculture groups, homebuilder and developer associations, wastewater industry representatives and environmental

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organizations. EPA received more than 14,000 comments – most of which supported the TMDL – and the Agency’s response to those comments is included as an appendix to the TMDL.



### Final Watershed Implementation Plans and TMDL

Since submittal of the draft WI Ps and release of the draft TMDL in September 2010, EPA worked closely with each jurisdiction to revi se and strengthen its plan. Because of this cooperative work and state leader ship, the final WIPs were sign ificantly improved. Examples of specific improvements include:

 Committing to more stringent nitrogen and phosphorus limits at wastewater treatment plants, including on the James River in Vi rginia. (Virginia, New York, Delaware)

 Pursuing state legislation to fund wastewater treatment plant upgrades, urban stormwater management and agricultural programs . (Maryland, Virginia, West Virginia)

 Implementing a progressive stormwater permit to reduce pollution. (Dis trict of Columbia)

 Dramatically increasing enforcement and complia nce of state requirements for agriculture. (Pennsylvania)

 Committing state funding to develop and impl ement state-of-the-art-technologies for converting animal manure to ener gy for farms. (Pennsylvania)

 Considering implementation of mandatory pr ograms for agriculture by 2013 if pollution reductions fall behind schedule. (Delaware, Maryland, Virginia)

These improvements enabled EPA to reduce and remove most federal backstops, leaving a few targeted backstops and a plan for enhanced oversi ght and contingency actions to ensure progress.

Backstop Allocations, Adjustments, and Actions Despite the significant improvement in the final WIPs , one of the jurisdictions did not meet all of its target allocations and two of the jurisdicti ons did not fully meet EPA’s expectations for reasonable assurance for specific pollution sector s. To address these few remaining issues, EPA included in the final TMDL several targeted b ackstop allocations, adjustments and actions. As a result of the jurisdictions’ significant impr ovements combined with EPA’s backstops, EPA believes the jurisdictions are in a position to implement their WIPs and achieve the needed pollution reductions. This approa ch endorses jurisdictions’ pollution reduction commitments, gives them the flexibility to do it their way first, and signals EPA’s commit ment to fully use its authorities as necessary to reduce pollution.

New York Wastewater – Backstop Allocation

 EPA closed the numeric gap between New York ’s WIP and its modified allocations by establishing a backstop that further redu ces New York’s wasteload allocation for wastewater. EPA is establishing an aggreg ate wasteload allocation for wastewater treatment plants.

 EPA calculated this backstop WLA using the nitrogen and phosphorus performance levels that New York committed to, but assumes that significant wastewater treatment plants (WWTPs) are at current flow rather than design flow.

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 EPA understands that New York plans to renew and/or modify WWTP permits upon completion of its Phase II WIP, consistent with the applicable TMDL allocations at that time. New York is reviewing engineering reports from WWTPs and, in its Phase II WIP, will provide information to support individual WLAs for these plants.

Pennsylvania Urban Stormwater – Backstop Adjustment

 EPA transferred 50 percent of th e stormwater load that is no t currently subject to NPDES permits from the load allocation to the wasteload allocation. The TMDL allocation adjustment increases reasonable assurance that pollution allocations from urban stormwater discharges will be achieved and maintained by signaling that EPA is prepared to designate any of these discharges as requiring NPDES pe rmits. Urban areas would only be subject to NPDES permit conditions protective of water quality as issued by Pennsylvania upon designation. EPA will consider this step if Pennsylvania does not demonstrate progress toward reductions in urban loads identified in the WIP. EPA may also pursue designation activities based on considerations othe r than TMDL and WIP implementation.

 EPA will maintain close oversight of general permits for the Pennsylvania stormwater sector (PAG-13 and PAG-2) and may object if permits are not protective of water quality standards and regulations. Upon review of Pe nnsylvania’s Phase II WIP, EPA will revisit the wasteload allocations for wastewater treatment plants, incl uding more stringent phosphorus limits, in the event that Pennsyl vania does not reissue PAG-13 and PAG-2 general permits for Phase II MS4s and constr uction that are protec tive of water quality by achieving the load reductions called for in Pennsylvania’s Phase I WIP.

West Virginia Agriculture – Backstop Adjustment

 EPA shifted 75 percent of West Virginia’s an imal feeding operation (AFO) load into the wasteload allocation and assumed full implem entation of barnyard runoff control, waste management and mortality composting practi ces required under a CAFO permit on these AFOs. The shift signals that any of these opera tions could potentially be subject to state or federal permits as necessary to protect wa ter quality. AFOs would only be subject to NPDES permit conditions as issued by West Virginia upon designation. EPA will consider this step if West Virginia does not achieve re ductions in agricultural loads as identified in the WIP. EPA may also pursue designation activ ities based upon considerations other than TMDL and WIP implementation.

 Based upon West Virginia's ability to dem onstrate near-term progress implementing the agricultural section of its WIP, includi ng CAFO Program authorization and permit applications and issuance, EPA will assess in the Phase II WIP whether additional federal actions, such as establishing more stringent wasteload allocations for wastewater treatment plants, are necessary to ensure th at TMDL allocations are achieved.

Enhanced Oversight and Contingencies While final WIPs were significantly improved and th e jurisdictions deserve credit for the efforts, EPA also has minor concerns with the assuranc e that pollution reductions can be achieved in certain pollution sectors in Penns ylvania, Virginia and West Vi rginia. EPA has informed these jurisdictions that it will consider future b ackstops if specific near-term progress is not demonstrated in the Phase II WIP.

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Pennsylvania Agriculture

 Based on Pennsylvania's ability to demons trate near-term progress implementing the agricultural section of its WIP, includi ng EPA approval for its CAFO program and enhanced compliance assurance with state re gulatory programs, EPA will assess in the Phase II WIP whether additional federal actions, such as shifting AFO loads from the load allocation to the wasteload allocation or establishing more stringent wasteload allocations for WWTPs, are necessary to ensure that TMDL allocations are achieved.

Pennsylvania Wastewater

 EPA established individual wast eload allocations for wastewater treatment plants in the TMDL to ensure that sufficient detail is pr ovided to inform individual permits for sources within the wasteload allocati on. Individual allocations do not commit wastewater plants to greater reductions than what the state has proposed in its WIP. Provisions of the TMDL allow, under certain circumstances, for modifi cations of allocations within a basin to support offsets and tr ading opportunities.

 EPA will assess Pennsylvania’s near-term ur ban stormwater and agriculture program progress and determine whether EPA should modify TMDL allocations to assume additional reductions from wa stewater treatment plants.

Virginia Urban Stormwater

 If the statewide rule and/or the Phase II WIP do not provide additional assurance regarding how stormwater discharges out side of MS4 jurisdictions will achieve nitrogen, phosphorus, and sediment reductions proposed in the fina l Phase I WIP and assumed within the TMDL allocations, EPA may shift a grea ter portion of Virginia’s urba n stormwater load from the load allocation to the wasteload allocation. This shift would signal that substantially more stormwater could potentially be subject to NPDES permits issued by the Commonwealth as necessary to protect water quality.

West Virginia Urban Stormwater

 If stormwater rules and/or the Phase II WI P do not provide additional assurance regarding how urban stormwater discharges outside of MS4 juri sdictions will achieve nitrogen, phosphorus, and sediment allocations proposed in the final Phase I WIP and assumed within the TMDL load allocations, EP A may shift a greater portion of West Virginia’s urban stormwater load from the load allocation to the wasteload allocation. The shift would signal that substantially more urban stormwater could potentially be subject to state permit coverage and/or federal Clean Water Act permit covera ge as necessary to protect water quality.

West Virginia Wastewater

 EPA established individual wasteload allocations for signifi cant wastewater treatment plants in the TMDL to ensure that sufficient de tail is provided to inform individual permits for sources within the wastewater wastel oad allocation. Individua l allocations do not commit wastewater plants to greater reductions than what the state has proposed in its WIP. Provisions of this TMDL allow, under certa in circumstances, for modifications of allocations within a basin to suppor t offsets and trading opportunities.

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 EPA will assess West Virginia’s near-term agriculture program progress and determine whether additional federal actions consistent with EPA’s December 29, 2009 letter, such as modifying TMDL allocations to assume additi onal reductions from wastewater treatment plants, are necessary to ensure th at TMDL allocations are achieved.

Ongoing oversight of Chesapeake Bay jurisdictions EPA will carefully review programs and permits in all jurisdictions. EPA’s goal is for jurisdictions to successfully implement their WIPs, but EPA is prepared to take necessary actions in all jurisdictions for insufficient WIP implem entation or pollution redu ctions. Federal actions can be taken at any time, although EPA will engage particularly during two-year milestones and refining the TMDL in 2012 and 2017. Actions include:

 Expanding coverage of NPDES permits to sources that are cu rrently unregulated

 Increasing oversight of st ate-issued NPDES permits

 Requiring additional pollution reductions from federally regulated sources

 Increasing federal enforcement and compliance

 Prohibiting new or expande d pollution discharges

 Conditioning or redirecting EPA grants

 Revising water quality standards to bette r protect local and downstream waters

 Discounting nutrient and sediment reduction pr ogress if jurisdiction cannot verify proper installation and management of controls



### FINAL TMDL As a result of the significantly improved WIPs and the removal and reduction of federal backstops, the final TMDL is shaped in large pa rt by the jurisdictions’ pl ans to reduce pollution. Jurisdiction-based solutions for reducing pollution was a long-stand ing priority for EPA and why the agency always provided the jurisdictions wi th flexibility to determine how to reduce pollution in the most efficient, cost-effective and acceptable manner.

Now, the focus shifts to jurisdictions’ implementation of the WIP policies and programs designed to reduce pollution on-the-ground and in-t he-water. EPA will conduct oversight of WIP implementation and jurisdictions’ progress toward meeting two-year milestones. If progress is insufficient, EPA will utilize contingencies to place additional controls on federally permitted sources of pollution, such as wastewater treatmen t plants, large animal ag riculture operations and municipal stormwater systems, as well as ta rget compliance and enforcement activities.

Federal agencies will greatly contribute to restoration of the Chesapeake Bay watershed, particularly through implementation of the new fe deral strategy created u nder President Obama’s Executive Order. Eleven federal agencies have committed to a comprehensive suite of actions and pursuit of critical environmental goa ls on the same 2025 timeline as the TMDL. Additionally, federal agencies will be establishi ng and meeting two-year milestones, with the specific charge of taking actions that directly support the jurisd ictions in reducing pollution and restoring water quality.

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‐ 14 December 29, 2010 The jurisdictions are expected to submit Phase II WIPs that provide local area pollution targets for implementation on a smaller scale; the timefra me for these Phase II WIPs will be determined in early 2011. Phase III WIPs in 2017 are expected to be designed to provide additional detail of restoration actions beyond 2017 and en sure that the 2025 goals are met.Chesapeake Bay TMDL



## Contents

SECTION 1. Introduction........................................................................................................ . 1-1

1.1 TMDLs a nd the CWA .......................................................................................................... ...1-2 1.2 History of the Ch esapeake Bay TMDL..................................................................................1-3 1.2.1 Regulatory and Ma nagement Initiatives .................................................................................... ... 1-3 1.2.2 Partnership Commitment to Develop the Chesapeake Bay TMDL .............................................. 1-8 1.2.3 President’s Chesapeake Bay Executiv e Order .............................................................................1- 10 1.3 Bay TMDL Process, Partner Coordination and Responsibilities......................................1-11 1.3.1 CBP Partnership and Organizational Structure............................................................................1 -11 1.4 Legal Framework for th e Chesapeake Bay TMDL ............................................................1-15 1.4.1 What is a TMDL? .......................................................................................................... ..............1-15 1.4.2 Why is EPA estab lishing this TMDL?....................................................................................... ..1-16 SECTION 2. Watershed and Impairment Description ............................................................ 2-1
2.1 General Watershed Setting.................................................................................................. ...2-1 2.2 Chesapeake Bay TMDL Scope ...............................................................................................2-6 2.2.1 Pollutants of Concern.................................................................................................... ................ 2-7 2.2.2 Chesapeake Bay Program Segmentation Scheme ......................................................................... 2-7 2.2.3 Jurisdictions’ 20 08 303(d) Listings...................................................................................... ........2-14 2.2.4 2008 303(d) Listing Segments Compared to Consent Decree and MOU Segments....................2-15 SECTION 3. Chesapeake Bay Water Quality Standards ........................................................ 3-1
3.1 Chesapeake Bay Water Quality Cr iteria and Designated Uses...........................................3-2 3.1.1 Tidal Water Designated Uses.............................................................................................. .......... 3-4 3.1.2 Dissolved Ox ygen Criteria................................................................................................ ............ 3-9 3.1.3 Chlorophy ll a Crite ria ................................................................................................... ...............3-11 3.1.4 Water Clarity/Underwate r Bay Grasses Criteria ..........................................................................3- 11 3.2 Jurisdictions’ Current Chesapeake Bay Water Quality Standards Regulations.............3-15 3.2.1 Delaware ................................................................................................................. .....................3-15 3.2.2 District of Columbia..................................................................................................... ................3-15 3.2.3 Maryland................................................................................................................. .....................3-16 3.2.4 Virginia ................................................................................................................. .......................3-17 3.3 Assessing Attainment of Chesapeake Bay Water Quality Standards...............................3-18 3.3.1 Defining Total Exceedances ............................................................................................... .........3-18 3.3.2 Defining Allo wable Exceedances ........................................................................................... .....3-20 3.3.3 Assessing Cr iteria Attainment............................................................................................ ..........3-22 SECTION 4. Sources of nitrogen, phosphorus and Sediment to the Chesapeake Bay.......... 4-1
4.1 Jurisdiction Loading Contributions.......................................................................................4- 1 4.2 Major River Basin Contributions ..........................................................................................4- 3

4.3 Pollutant Source Sector Contributions..................................................................................4-5 4.4 Regulated Point Sources.................................................................................................... ......4-6 4.4.1 Significant and Nonsi gnificant Municipal and I ndustrial Fa cilities .............................................. 4-7 4.4.2 Basinwide NPDES Permitting Approach...................................................................................... 4-8 4.5 Regulated Point Sou rce Load Summaries.............................................................................4-9

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4.5.1 Municipal Wastewater Dischargin g Fac ilities

.............................................................................. 4-9 4.5.2 Industrial Di scharge F acilitie s.......................................................................................... ............4-13 4.5.3 Combined Sewer Overflows ................................................................................................. .......4-17 4.5.4 Sanitary Se wer Overflows ................................................................................................. ..........4-21 4.5.5 NPDES Permitted Stormwater............................................................................................... ......4-22 4.5.6 Concentrated Anim al Feeding Operations ................................................................................... 4-25 4.6 Nonpoin t Sources........................................................................................................... ........4-28 4.6.1 Agri culture .............................................................................................................. .....................4-29 4.6.2 Atmospheri c Deposition ................................................................................................... ...........4-33 4.6.3 Forest Lands............................................................................................................. ....................4-36 4.6.4 On-site Wastewater Treatment Systems ..................................................................................... .4-37 4.6.5 Nonregulated Stormwater Runoff........................................................................................... .....4-38 4.6.6 Oceanic Inpu ts ........................................................................................................... ..................4-39 4.6.7 Streambank and Tida l Shoreline Erosion................................................................................... ..4-41 4.6.8 Tidal Re suspension ....................................................................................................... ...............4-42 4.6.9 Wildlife ................................................................................................................. .......................4-43 4.6.10 Natura l Backgr ound ...................................................................................................... ...............4-44 SECTION 5. Chesapeake Bay Monitoring and Modeling Frameworks................................. 5-1
5.1 Technical Monitoring and Modeling Requirements.............................................................5-1 5.2 Bay Monitoring Framework Overview .................................................................................5-2 5.2.1 Partnership’s Chesapeake Ba y Tidal Monitoring Network........................................................... 5-3 5.2.2 Partnership’s Watershe d Monitoring Network.............................................................................5- 12 5.2.3 Data Qua lity and Access .................................................................................................. ............5-14 5.2.4 Data Subm ission and Quality Assurance .................................................................................... .5-16 5.2.5 Monitoring Applications in Ch esapeake Bay TMDL Development............................................5-18 5.3 Modeling Framework Overview ..........................................................................................5-18 5.4 Chesapeake Bay Airshed Model...........................................................................................5-21 5.5 Chesapeake Bay Land Change Model .................................................................................5-24 5.5.1 Motivations for Developing Future Land Use Estimates .............................................................5-24 5.5.2 Scale of Chesapeake Bay Land Change Model Future Land Use Estimates ...............................5-24 5.5.3 Components of Chesapeake Bay Land Change Model Future Land Use Estimates ....................5-26 5.6 Chesapeake Bay SPARROW Model....................................................................................5-27 5.7 Chesapeake Bay Scenario Builder .......................................................................................5-28 5.8 Phase 5.3 Chesapeake B ay Watershed Model.....................................................................5-30 5.8.1 Bay Watershed Model Segmentation......................................................................................... ..5-30 5.8.2 Bay Watershe d Model Setup................................................................................................ ........5-32 5.8.3 Pollutant Sour ce Representation .......................................................................................... ........5-37 5.8.4 Calib ration.............................................................................................................. ......................5-38 5.9 Chesapeake Bay Water Quality and Sediment Transport Model.....................................5-38 5.9.1 Nonpoint Source Loads.................................................................................................... ............5-41 5.9.2 Point S ource Lo ads ....................................................................................................... ...............5-41 5.9.3 Atmosphe ric Loads ........................................................................................................ ..............5-41 5.9.4 Bank Loads ............................................................................................................... ...................5-42 5.9.5 Wetlands ................................................................................................................. .....................5-42 5.9.6 Mode l Setu p.............................................................................................................. ...................5-42 5.10 Chesapeake Bay Criteri a Assessment Program..................................................................5-43 5.11 Climate Change Simulation................................................................................................. .5-43

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SECTION 6. Establishing the Allocatio ns for the Basin-Jurisdictions.................................. 6-1
6.1 Establishing the Overa ll Model Parameters .........................................................................6-2 6.1.1 Hydrologic Period........................................................................................................ ................. 6-2 6.1.2 Seasonal Variation ....................................................................................................... ................. 6-3 6.1.3 Daily Loads.............................................................................................................. ..................... 6-5 6.2 Establishing the Nitrogen and Phosphorus Related Model Parameters.............................6-8 6.2.1 Critical Conditions ...................................................................................................... .................. 6-8 6.2.2 Assessment Procedures for DO and Chlorophyll a Standards ...................................................... 6-9 6.2.3 Addressing Reduced Sensitivity to Load Redu ctions at Low Nonattainment Percentages..........6-10 6.2.4 Margin of Safety ......................................................................................................... .................6-13 6.3 Methodology for Establishing the Basin-Jurisdiction Allocations for Nitrogen and Phosphorus..................................................................................................................... ........6-16 6.3.1 Accounting for Relativ e Effectiveness of the Major River Basins on Tidal Water Quality.........6-17 6.3.2 Determining Controllable Load ............................................................................................ .......6-20 6.3.3 Relating Relative Impact to N eeded Controls (A llocations)........................................................6-24 6.4 Establishing the Basin-Jurisdiction Al locations for Nitrogen and Phosphorus...............6-25 6.4.1 Setting the Atmospheric Nitr ogen Deposition Allocation............................................................6-26 6.4.2 Determining the Basinwide Nitrogen and Phosphorus Target Load Based on Dissolved Oxygen......................................................................................................................... ................6-28 6.4.3 Allocating Nitrogen and Phosphorus Loads to Jurisdictions within the Bay Watershed .............6-30 6.4.4 Resolving Dissolved Oxygen and Chlo rophyll a Nonattainin g Bay Segments............................6-32 6.4.5 Allocation Considerations for the Headwater Ju risdictions (New York and West Virginia).......6-38 6.4.6 Nitrogen-to-Phosphorus Exchanges......................................................................................... ....6-39 6.5 Establishing the Sediment-R elated Model Parameters......................................................6-41 6.5.1 Critical Conditions fo r Water Clarity and SAV ...........................................................................6 -41 6.5.2 Assessment Procedures for th e Clarity and SAV Standards ........................................................6-42 6.5.3 Addressing Reduced Sensitivity to Load Redu ctions at Low Nonattainment Percentages..........6-43 6.5.4 Explicit Margin of Safety for Sediment ................................................................................... ....6-44 6.6 Establishing the Basin-Jurisdiction Allocations for Sediment ..........................................6-44 6.6.1 Methodology for Determin ing Sediment A llocations ..................................................................6-45 6.6.2 Addressing Water Clarity /SAV Nonattaining Segments .............................................................6-45

6.7 Basin-Jurisdiction Allocation s to Achieve the Bay WQS...................................................6-48 6.7.1 Basin-Jurisdicti on Allocations Tables.................................................................................... ......6-48 6.7.2 Correction of the West Virg inia Sediment Allocation .................................................................6-48 6.8 Attainment of the District of Columbia pH Water Quality Standard ..............................6-49
SECTION 7. Reasonable Assurance and Accountability Framework ................................... 7-1

7.1 Reasonable Assurance....................................................................................................... ......7-1 7.1.1 Overview of the Ac countability Framework................................................................................. 7-2 7.1.2 Federa l Stra tegy

......................................................................................................... ................... 7-3 7.1.3 Funding .................................................................................................................. ....................... 7-4 7.1.4 Air Emissi on Reductions. ................................................................................................. ............ 7-4 7.2 Accountability Framework................................................................................................... ..7-4 7.2.1 Watershed Implementation Plans........................................................................................... ....... 7-6 7.2.2 Two-Year Milest ones...................................................................................................... .............. 7-8 7.2.3 Chesapeake Bay TMDL Tracki ng and Accountab ility Syst em ...................................................7-10 7.2.4 Federal EPA Actions...................................................................................................... ..............7-11

iii December 29, 2010Chesapeake Bay TMDL

SECTION 8. Watershed Implementation Plan Evaluation and Resultant Allocations ......... 8-1
8.1 WIP Evaluation Methodology ................................................................................................8 -3 8.1.1 Quantitative Evaluation of the Final Ph ase I WIPs....................................................................... 8 -3 8.1.2 Qualitative Evaluation of the Final Ph ase I WIPs......................................................................... 8-4

8.2 WIP Evaluati on Results ..................................................................................................... .....8-5 8.2.1 Target Allo cation Attainment ............................................................................................. .......... 8-5 8.2.2 Reasonable Assurance..................................................................................................... .............. 8-9 8.3 Allocation Methodology ..................................................................................................... .....8-9 8.3.1 Backstop Allo cation Met hodology .......................................................................................... ....8-10 8.3.2 Backstop Adjustment (Allo cation Shift) Me thodology................................................................8-10 8.3.3 Assumptions Suppo rting the A llocatio ns................................................................................... ..8-12 8.4 Allocations by Jurisdiction ................................................................................................ ...8-17 8.4.1 Delaware ................................................................................................................. .....................8-17 8.4.2 District of Columbia..................................................................................................... ................8-19 8.4.3 Maryland................................................................................................................. .....................8-20 8.4.4 New York................................................................................................................. ....................8-22 8.4.5 Penn sylvania ............................................................................................................. ...................8-24 8.4.6 Virginia ................................................................................................................. .......................8-27 8.4.7 West Virginia............................................................................................................ ...................8-30 8.5 Allocation Summary Chart................................................................................................... 8-33
SECTION 9. Chesapeake Bay TMDLs .................................................................................... 9-1
9.1 Bay Segment Annual and Daily Allocations to Meet WQS..................................................9-1
SECTION 10. Implementation an d Adaptive Management.................................................... 10-1

10.1 Future Growth ............................................................................................................. ..........10-1 10.1.1 Designating Target Loads for New or Increased Sources............................................................10-1 10.1.2 Offset Programs ......................................................................................................... ..................10-1 10.1.3 Additional Offs et Program Features ...................................................................................... ......10-2 10.1.4 EPA’s Oversight Role of Ju risdictions’ Offset Programs ............................................................10-3 10.2 Water Quality Trading ..................................................................................................... ....10-3

10.3 Future Modifications to the Chesapeake Bay TMDL ........................................................10-4

10.4 Federal Facilities and Lands.............................................................................................. ...10-5 10.5 Factoring in Effects from Continued Climate Change.......................................................10-7 10.6 Sediment behind the Susquehanna River Dams .................................................................10-7

10.7 Filter Feeders ............................................................................................................ .............10-8
SECTION 11. Public Participation .......................................................................................... 11-1

11.1 Stakeholder and Local Government Outreach and Involvement .....................................11-1 11.1.1 Open Collaborati on with Stakeholders .................................................................................... ....11-1 11.1.2 Outreach to Local Governme nts and Elected Official s................................................................11-1 11.1.3 Local Pilots ............................................................................................................ ......................11-2

11.2 Public Outreach ........................................................................................................... ..........11-2 11.2.1 Public Mee tings ...........................................................................................................................11-2 11.2.2 Webinars to Expand Audiences ............................................................................................ .......11-4 11.2.3 Chesapeake Bay TMDL Website............................................................................................. ....11-5 11.2.4 Pub lic No tices ..............................................................................................................................11-5

iv December 29, 2010Chesapeake Bay TMDL

11.3 Responses to Public Comments ............................................................................................11 -5 11.4 Interaction with States, D.C. on Watershed Implementation Plans .................................11-6
SECTION 12. References ......................................................................................................... 12-1
SECTION 13. Glossary ........................................................................................................... .. 13-1

SECTION 14. Abbreviations..................................................................................................... 1 4-1



### Appendices

Appendix A Chesapeake Bay TMDL Contributors Appendix B Index of Documents Supporting the Chesapeake Bay TMDL Appendix C Record of Chesapeake Bay TMDL Related Chesapeake Bay Program Committee, Team and Workgroup and Partne r/Stakeholder Meetings Appendix D Evaluation of the Most Protectiv e Chesapeake Bay Dissolved Oxygen Criteria Appendix E Summary of Initial Climate Cha nge Impacts on the Chesapeake Bay Watershed Flows and Loads Appendix F Determination of the Hydrologic Period for Model Application Appendix G Determination of Critical Conditions for the Chesapeake Bay TMDL Appendix H Criteria Assessment Procedures using Model Scenario Output with Bay Monitoring Data Appendix I Documentation of the Reduced Sensitivity to Load Reductions at Low Nonattainment Percentages Appendix J Key Chesapeake Bay TMDL Reference and Management Model Scenarios: Definitions and Descriptions Appendix K Allocation Methodology for Relatin g Relative Impact to Needed Controls Appendix L Setting the Chesapeake Bay Atmo spheric Nitrogen Deposition Allocations Appendix M Chesapeake Bay Water Quality/Sediment Transport Model Management Scenario Attainment Assessment Results and 2008 303(d) Chesapeake Bay List Assessment Results Appendix M-1 Chesapeake Bay Dissolv ed Oxygen Criteria Attainment Assessment Results Appendix M-2 Chesapeake Bay Chlorophyll a Criteria Attainment Assessment Results Appendix M-3 Chesapeake Bay Water Clarity/SAV Criteria Attainment Assessment Results Appendix M-4 Chesapeake Bay Segments 2008 303(d) List Assessment Results Appendix N Resolution of Segments Faili ng to Attain the Applicable Criteria

v December 29, 2010Chesapeake Bay TMDL

Appendix O Setting the Chlorophyll a Criteria-Based Nutrient Allocations for the James River Watershed Appendix P Setting the Water Clarity/S AV Criteria-Based Sediment Allocations Appendix Q Detailed Annual Ches apeake Bay TMDL WLAs and LAs Appendix R Chesapeake Bay TMDL Daily WLAs and LAs Appendix S Offsets for New or Increased Loadings of Nitrogen, Phosphorus and Sediment to the Chesapeake Bay Watershed Appendix T Sediment behind the Susque hanna Dams Technical Documentation Appendix U Accounting for the Benefits of Filter Feeder Restoration Technical Documentation Appendix V Best Management Practice (BMP ) Implementation Rates for Final Scenarios Appendix W Responses to Public Comme nts Received on the September 24, 2010, Draft Chesapeake Bay TMDL Appendix X Staged Implementation Approach fo r Wastewater Treatmen t Facilities in the Virginia James River Basin

vi December 29, 2010Chesapeake Bay TMDL



## Tables
Table ES-1. Chesapeake Bay TMDL watershe d nitrogen, phosphorus and sediment final allocations by jurisdiction and by major river basin. .............................................ES-7 Table 1-1. URLs for accessing the seven Chesapeake Bay watershed jurisd ictions’ tributary strategies .................................................................................................... 1-7 Table 1-2. Summary of Chesapeake Bay TM DL relevant actions agreed to by the CBP’s Principals’ Staff Committee during its October 1, 2007, me eting ............... 1-9 Table 1-3. Virginia consent decree (CD) waters impaired for dissolved oxygen (DO) and/or nutrients addressed by the Chesapeake Bay TMDL ................................... 1-18 Table 1-4. District of Columbia consent de cree (CD) waters impai red for pH addressed by the Chesapeake Bay TMDL .............................................................................. 1-19 Table 2-1. The Chesapeake Bay 303(d) tidal segments with consent decree (CD)/memorandum of understanding (M OU) and 303(d) listing status by major river basin and jurisdiction .......................................................................... 2-10 Table 2-2. Comparison of consent decree/M OU segm ents with total number of Bay segments ................................................................................................................. 2-15 Table 3-1. Chesapeake Bay water qualit y criteria and design ated use related documentation and addenda ..................................................................................... 3-2 Table 3-2. Five Chesapeake Ba y tidal waters designated uses ................................................. 3-4 Table 3-3. Current tidal water desig nated uses by Chesapeake Bay segment .......................... 3-6 Table 3-4. Current Chesapeake Bay DO criteria ..................................................................... 3-10 Table 3-5. Summary of Chesapeake Bay wate r clar ity criteria for application to shallow-water Bay grass designated use habitats .................................................. 3-12 Table 3-6. Chesapeake Bay SAV restorati on acreage goals and application depths .............. 3-12 Table 3-7. Links for accessing the current wa ters quality standard s (WQS) regulatio ns for Delaware, the District of Columbia, Maryland, and Virginia .......................... 3-15 Table 3-8. District of Columbia designated uses for surface waters ....................................... 3-16 Table 3-9. Numeric criteria fo r the District of Columb ia’s tidally influenced waters ............ 3-16 Table 3-10. Segment- specific chlorophyll a crite ria for Virginia’s tidal James River
waters ..................................................................................................................... 3-17 Table 3-11. Estimated percent spatial criteria ex ceedances and associated cumulative probabilities ............................................................................................................ 3-19 Table 4-1. Percentage of total nitrog en de livered to the Bay from each jurisdiction by pollutant source sector ............................................................................................. 4-5 Table 4-2. Percentage of total phosphorus de livered to the Bay from each jurisdiction by pollutant source sector ........................................................................................ 4-5 Table 4-3. Percentage of sediment deliv ered to the Bay from each jurisdiction by pollutant source sector ............................................................................................. 4-6 Table 4-4. Jurisdiction-specific definitions of significant municipal and industrial wastewater discharge facilities ................................................................................ 4-7 Table 4-5. Significant and nonsignificant municipal and industrial wastewater discharging facilities by jurisd iction as of December 2010..................................... 4-8 Table 4-6. Nitrogen and phosphorus permit tracking summary under the Basinwide NPDES Wastewater Permitting Approach, through December 2010 ..................... 4-9 Table 4-7. Municipal wastewater facilities by jurisdiction ..................................................... 4-10

vii December 29, 2010Chesapeake Bay TMDL

Table 4-8. Model estimated 2009 municipal wa stewater loads by jurisdiction delivered to Chesapeake Bay................................................................................................. 4-10 Table 4-9. Model estimated 2009 municipal wastewater loads by major river basin delivered to Chesapeake Bay................................................................................. 4-10 Table 4-10. Industrial wast ewater facilities .............................................................................. 4-14 Table 4-11. 2009 Load estimates of i ndustrial facility discharges............................................ 4-14 Table 4-12. 2009 Flow, total nitr ogen, and total phosphorus lo ad estimates of industrial wastewater facility discharges by major river basin.............................................. 4-14 Table 4-13. Combined sewer system co mmunities in the Bay watershed ................................ 4-18 Table 4-14. NPDES stormwater permittees by jurisdiction and in the Chesapeake Bay watershed, summer 2009 ....................................................................................... 4-25 Table 4-15. Federal numeric thresholds fo r small, medium, and large CAFOs........................ 4-26 Table 4-16. Estimated number of st ate or federal permitted CAFOs........................................ 4-28 Table 4-17. Estimated portion of deposited NOx loads on the Chesapeake watershed from four source sectors—EGUs, mobile sources, industry, and all other sources in 1990 and 2020....................................................................................... 4-36 Table 4-18. Chesapeake Bay Water Quality a nd Sediment Transport Model -simulated SAV acres under a range of sediment scoping scenarios compared with the 2010 Tributary Strategy scenario........................................................................... 4-44 Table 5-1. Modeling tools supporting development of the Chesapeake Bay TMDL ............. 5-20 Table 5-2. Phase 5.3 Chesapeake Bay Watershed Model land uses ....................................... 5-33 Table 6-1. ADM for calculating daily maximum loads ............................................................ 6-7 Table 6-2. Different approaches available under the explicit and implicit MOS types .......... 6-14 Table 6-3. Relative effectiveness (measured as DO concentration per edge-of-stream pound reduced) for nitrogen and phosphorus for watershed jurisdictions by major river basin and above and below the fall line .............................................. 6-19 Table 6-4. Pollutant sources as defined for the No Action and E3 model scenarios .............. 6-23 Table 6-5. Chesapeake Bay designated use se gments showing percent nonattainment of the applicable Bay DO WQS under th e basinwide nitrogen and phosphorus target loadings (million pounds per year) .............................................................. 6-33 Table 6-6. Tributary strategy scenario a nd nitrogen and phosphorus-based allocation scenario’s total suspended solids loads (millions of pounds) by watershed jurisdiction ............................................................................................................. 6-43 Table 6-7. Chesapeake Bay watershed nitrogen and phosphorus and sediment allocations by major river basin by ju risdiction to achieve the Chesapeake Bay WQS ............................................................................................................... 6-50 Table 6-8. Chesapeake Bay watershed nitrogen and phosphorus and sediment allocations by jurisdiction by major river basin to achieve the Chesapeake Bay WQS ............................................................................................................... 6-51 Table 7-1. Eight elements of the jurisdic tions’ Watershed Implementation Plans ................... 7-6 Table 7-2. Comparison of elements within the Chesapeake Bay TMDL and Phase I, II, and III WIPs............................................................................................................. 7-7 Table 8-1. Comparison between nitrogen, phos phorus, and sediment jurisdiction-wide allocations and final Phase I Watershed Implementation Plans, in millions of pounds per year........................................................................................................ 8-6

viii December 29, 2010Chesapeake Bay TMDL

Table 8-2. Comparison between the nitr ogen, phosphorus, and sediment basinjurisdiction allocations and final Phase I Watershed Implementation Plans, in million pounds per year ........................................................................................... 8-7 Table 8-3. Percent reductions in edge-of- stream loads to achieve urban stormwater WLAs..................................................................................................................... 8-14 Table 8-4. EPA backstop allocations, adjustme nts, and actions based on assessment of final Phase I WIPs.................................................................................................. 8-16 Table 8-5. Chesapeake Bay watershed nitr ogen, phosphorus, and sediment allocations by jurisdiction and by major river basin, in millions of pounds per year .............. 8-33 Table 9-1. Chesapeake Bay TMDL total ni trogen (TN) annual allocations (pounds per year) by Chesapeake Bay segment to attain Chesapeake Bay WQS ....................... 9-2 Table 9-2. Chesapeake Bay TMDL total phos phorus (TP) annual allocations (pounds per year) by Chesapeake Bay segment to attain for the proposed amended Chesapeake Bay WQS ............................................................................................. 9-7 Table 9-3. Chesapeake Bay TMDL sedime nt (TSS) annual allocations (pounds per year) by Chesapeake Bay segment to attain Chesapeake Bay WQS ..................... 9-12 Table 9-4. Edge of Stream (EOS) WLAs (Annual) for the 478 significant permitted dischargers to meet TMDLs to a ttain the Chesapeake Bay WQS ......................... 9-17

ix December 29, 2010Chesapeake Bay TMDL



## Figures
Figure ES-1. A nitrogen, phosphorus and sedime nt TMDL has been developed for each of the 92 Chesapeake Bay segment watersheds. ....................................................ES-4 Figure ES-2. Sub-basins across the Chesapeake Bay watershed with the highest (red) to lowest (blue) pound for pound nitrogen pollutant loading effect on Chesapeake Bay water q uality. ..............................................................................ES-6 Figure 1-1. CBP’s orga nizational structure. ............................................................................. 1-12 Figure 2-1. The Chesapeake Bay watershed with major rivers and cities. ................................. 2-2 Figure 2-2. Hydrogeomorphic regions of the Chesapeake Bay watershed. ............................... 2-3 Figure 2-3. Chesapeake Bay watershed land cover. ................................................................... 2-5 Figure 2-4. Reported and pr ojected human population grow th in the Chesapeake Bay watershed 1950–2030.

............................................................................................. 2-6 Figure 2-5. The 92 Chesapeake Bay segments. .......................................................................... 2-8 Figure 2-6. The 92 Chesapeake Bay segment watersheds. ......................................................... 2-9 Figure 3-1. Conceptual illust ration of the five Chesapeake Bay tidal water designated use

zones. ....................................................................................................................... 3-5 Figure 3-2. Dissolved oxygen concentrations (mg/L) required by different Chesapeake Bay species and biological comm unities. ................................................................ 3-9 Figure 3-3. Example cumulative fr equency distribution (CFD) curve. .................................... 3-19 Figure 3-4. Default reference curve used in the a ttainment assessment of Chesapeake Bay water quality criteria for which biol ogically based reference curves have not yet been derived. .............................................................................................. 3-21 Figure 3-5. Example reference and asse ssment curves showing allowable and nonallowable exceedances.

.......................................................................................... 3-21 Figure 3-6. Direct model assessment of open water (a), and deep water and deep chan nel (b) criteria. .............................................................................................................. 3-24 Figure 4-1. Modeled estima ted total nitrogenloads delivered to the Chesapeake Bay by jurisdiction in 2009. ................................................................................................. 4-1 Figure 4-2. Model estimated to tal phosphorus loads delivered to the Chesapeake Bay by jurisdiction in 2009. ................................................................................................. 4-2 Figure 4-3. Model estimated to tal sediment loads delivered to the Chesapeake Bay by jurisdiction in 2009. ................................................................................................. 4-2 Figure 4-4. Model estimated total nitrogen loads delivered to the Chesapeake Bay by major tributary in 2009. ........................................................................................... 4-3 Figure 4-5. Model estimated to tal phosphorus loads delivered to the Chesapeake Bay by major tributary in 2009. ........................................................................................... 4-4 Figure 4-6. Model estimated to tal sediment loads delivered to the Chesapeake Bay by major tributary in 2009. ........................................................................................... 4-4 Figure 4-7. Significant wastewater treatment facilities in the Chesapeake Bay watershed. .... 4-11 Figure 4-8. Nonsignificant m unicipal wastewater treatment facilities in the Chesapeake Bay watershed........................................................................................................ 4-12 Figure 4-9. Significant industria l wastewater discharge faci lities in the Chesapeake Bay watershed. .............................................................................................................. 4-15 Figure 4-10. Nonsignificant i ndustrial wastewater discharge facilities in the Chesapeake Bay watershed........................................................................................................ 4-16 Figure 4-11. CSO communities in th e Chesapeake Bay watershed. .......................................... 4-20

x December 29, 2010Chesapeake Bay TMDL

Figure 4-12. Phase I and II MS4s in the Chesapeake Bay watershed. ....................................... 4-24 Figure 4-13. 1985 and 2009 modeled total nitr ogen, phosphorus, and sediment loads from agricultural lands ac ross the Chesapeake Bay watershed...................................... 4-30 Figure 4-14. 2007 Chesapeake Bay watershed poultry populations by jurisdiction. ................. 4-31 Figure 4-15. 2007 Chesapeake Bay watershed li vestock populations by jurisdiction. .............. 4-32 Figure 4-16. Principle area of NOX emissions (outlined in blue) that contribute nitrogen deposition to the Chesapeake Bay and its watershed (solid blue fill) (the Bay airshed)................................................................................................................... 4-34 Figure 4-17 Trend of estimated average nitrat e and ammonia depositi on concentrations in the Phase 5 Model domain from 1984 to 2005...................................................... 4-35 Figure 4-18. Estimated 2001 annual total deposition of nitrogen (kg/ha) to North America and adjacent coastal ocean..................................................................................... 4-40 Figure 4-19. Relative estimates of sources of erosion from land sources (crop, forest, or construction) or bank sources banks and ditch beds)............................................. 4-41 Figure 4-20. Sources of total suspended so lids in the Chesapeake including the two components of shoreline erosions, fa stland and nearshore erosion. ...................... 4-42 Figure 4-21. Estimated tidal sediment inputs for 1990 from the Chesapeake Bay watershed and from shore erosion. Shor eline sediment inputs (here labeled bank load) are estimated to be about e qual to watershed inputs (here labeled as nonpoint source). ............................................................................................... 4-43 Figure 5-1. Tidal Chesapeake Bay water qua lity monitoring network stations. ........................ 5-4 Figure 5-2. Shallow-water monitoring illustrating segment completion and latest rotation for Maryland. ........................................................................................................... 5-7 Figure 5-3. 2003-2008 Chesapeake Bay stratified random benthic sampling sites used to estimate habitat impairment through benthic community condition assessment................................................................................................................ 5-8 Figure 5-4. Flightlines for the annual Chesapeake Bay SAV Aerial Survey. ............................ 5-9 Figure 5-5. Illustration of mapped SAV beds, individua l bed coding, bed density estimates, and species identifica tion (from ground surveys)................................. 5-10 Figure 5-6. Chesapeake Bay wate rshed monitoring network................................................... 5-13 Figure 5-7. Chesapeake Bay tidal and wate rshed water quality monitoring networks’ participants arrayed by their role in sample collection, laboratory analysis, and/or data reporting.............................................................................................. 5-17 Figure 5-8. Chesapeake Bay TM DL modeling framework...................................................... 5-19 Figure 5-9. Atmospheric deposition monitori ng stations used in the Chesapeake Bay airshed nitrogen wet depos ition regression model................................................. 5-22 Figure 5-10. The Community Multiscale Air Quality Model’s 12 km grid over the Phase 5.3 Chesapeake Bay Watershed Model county segmentation. .............................. 5-23 Figure 5-11. 2006 Land cover conditions in the Chesapeake Bay watershed and intersecting counties............................................................................................... 5-25 Figure 5-12. An example of the Chesapeake Bay SPARROW Model output showing delivered yields of tota l nitrogen in the Chesapeake Bay watershed..................... 5-28 Figure 5-13. Scenario Builder conceptual process. ................................................................... 5-29 Figure 5-14. Segmentation and reach simulation of the Phase 5.3 Chesapeake Bay Watershed Model................................................................................................... 5-31

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Figure 5-15. Phase 5.3 Chesapeake Bay Waters hed Model hydrology ( upper panel) and water quality (lower panel) monitoring calibration stations overlaid on the Phase 5.3 Bay Watershed Model’s river segments................................................ 5-39 Figure 5-16. The detailed 57,000 cell grid of the Chesapeake Bay Water Quality and Sediment Transport Model. ................................................................................... 5-40 Figure 6-1. Graphic comparison of allowable exceedance compared to actual exceedance. ............................................................................................................ 6-11 Figure 6-2. Example of DO criteria nonattainment results from a wide range of nitrogen and phosphorus load reduction model scenarios. .................................................. 6-12 Figure 6-3. Example of a James Rive r segment’s spring chlorophyll a WQS nonattainment results from a wide ra nge of TN loading Chesapeake Bay Water Quality Model scenarios. ............................................................................ 6-13 Figure 6-4. Relative effectiveness for nitroge n for the watershed jurisdictions and major rivers basins, above and below the fall line, in descending order.......................... 6-20 Figure 6-5. Relative effectiv eness illustrated geographica lly by subbasins across the Chesapeake Bay watershed for nitrogen................................................................ 6-21 Figure 6-6. Relative effectiveness for illust rated geographically by subbasins across the Chesapeake Bay watershed for phosphorus........................................................... 6-22 Figure 6-7. Allocation methodology example s howing the hockey stick and straight line reductions approaches, respectively, to wastewater (red line) and all other sources (blue line) for nitrogen.............................................................................. 6-25 Figure 6-8. Principal areas of nitrogen oxide (blue line) a nd ammonia (red line) emissions that contribute to nitroge n deposition to the Chesapeake Bay and its watershed (dark blue fill). ................................................................................. 6-27 Figure 6-9. Chesapeake Bay water quality m odel simulated DO criteria attainment under various TN and TP loading scenarios. ................................................................... 6-29 Figure 6-10. Example allocation met hodology application for phosphorus............................... 6-31 Figure 6-11. Example allocation methodol ogy application for nitrogen.................................... 6-31 Figure 6-12. Potomac River chlorophyll a mon itoring data compared with the District’s summer seasonal mean chlorophyll a water quality criteria.................................. 6-36 Figure 6-13. Tidal James River monitoring data for chlorophyll a at station TF5.5 (in the upper tidal James River near Hopewell, Virginia) compared to Virginia’s James River segment-season specific chlorophyll a criteria.................................. 6-37 Figure 6-14. James River nonattainment of the chlorophyll a WQS at various load scenarios................................................................................................................. 6-38 Figure 6-15. TN:TP exchanges based on anoxic volume days and varying TP loads................ 6-40 Figure 6-16. TN: TP exchanges based on chlo rophyll a concentrations and varying TP loads. ...................................................................................................................... 6-4 0 Figure 6-17. Chesapeake Bay SAV/Water Clarit y WQS attainment from monitoring data assessment.............................................................................................................. 6-46 Figure 6-18. Model simulated sediment loads by scenario compared with the range of sediment allocations (billions of pounds per year as total suspended sediment)................................................................................................................ 6-49 Figure 6-19. District of Columbia’s Roosev elt Island station pH versus chlorophyll a monitoring data regression..................................................................................... 6-52 Figure 7-1. Relationship between WI Ps and 2-year milestones................................................. 7-9

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## Foreword

This document describes the technical, legal, and policy underpinnings of the Chesapeake Bay Total Maximum Daily Load (TMDL). While EPA Regions 2 and 3 are establishing this TMDL, it represents the product of decad es of scientific research, monitoring, assessment, and model application, and years of focused dialogue and analysis among EPA, our six watershed state partners and the District of Co lumbia, and numerous stakeholders. This document has benefited from the input of thousands of professionals a nd citizens dedicated to the restoration of the Chesapeake Bay. In accordance with the Clean Water Act and Executive Order 13508 (signed by President Obama on May 12, 2009), the Chesapeake Bay TMDL provides a critical plan to restore and maintain the living resources of the Chesapeake Bay.

A TMDL is required by the Clean Water Act for wa ters that are on state lists identifying waters that are impaired – i.e., not at taining state adopted and EPA approved water quality standards. Most of the waters of the Chesapeake Bay and its tidal tributaries and embayments are on the three states’ (Maryland, Virginia , and Delaware) and the District ’s lists of impaired waters because of excess nitrogen, phosphorus, and sediment pollution. The Chesapeake Bay TMDL identifies the loadings of nitrogen, phosphorus, a nd sediment that are necessary to achieve the applicable jurisdiction’s water quality standard s for the Bay and its tidal tributaries and embayments for dissolved oxygen, chlorophyll a (an indicator of algae), water clarity, and submerged aquatic vegetation (SAV, or underw ater Bay grasses). For this reason, the Chesapeake Bay TMDL has been described as a pollution diet defining th e pollutant loadings necessary to attain water quality standards and restore the aquatic life resources of the Chesapeake Bay.

The Chesapeake Bay receives waters from thousands of streams and rivers within seven jurisdictions in the mid-Atlantic region of the Un ited States: Delaware, the District of Columbia, Maryland, New York, Pennsylvania, Virginia, and West Virginia. These waters drain to the Chesapeake Bay and, therefore, contribute polluta nt loadings to the Bay. The Chesapeake Bay TMDL also establishes total maximum daily loads from these watersheds and jurisdictions for each of the 92 impaired segments that comprise the waters of the Chesapeake Bay and its tidal tributaries and embayments. Thus, the Chesapeake Bay TMDL is actually an assemblage of 276 TMDLs: individual TMDLs for each of the 3 pollutants— nitrogen, phosphorus, and sediment— for each of the 92 segments (3 x 92 = 276).

The purpose of the Chesapeake Bay TMDL is to id entify the pollutant loading reductions needed to meet the applicable Bay water quality sta ndards. The TMDL, thus, allocates loads to all pollutant source sectors in all parts of the Bay’s 64,000 square mile watershed. Because of the watershed-wide nature of these loading reduc tions, the water quality benefits from these reductions will not be limited to the Bay and its tidal tributaries and embayments. In fact, the watershed’s headwaters from the location the pol lutant reductions are made to the point they enter the Bay or its tidal tribut aries should benefit from some m easure of improved water quality. The controls necessary to reduce nitrogen, phosphorus, and sediment also are likely to reduce other pollutants like bacteria and chemical contaminants.

While the Chesapeake Bay TMDL establishes th e pollutant loadings for nitrogen, phosphorus, and sediment needed to restore and maintain a healthy Bay, the TMDL is essentially an

xiii December 29, 2010Chesapeake Bay TMDL

information and planning tool that does not , by itself, implement the needed controls. Implementation mechanisms available under other provisions of the Clean Water Act, Clean Air Act, state laws, and federal and state regulations, and local ordinances, as well as appropriate levels of funding, are needed to achieve th ese loading targets. The Bay TMDL will be implemented using an accountability framework th at includes the seven jurisdictions’ Watershed Implementation Plans (WIPs), two-year mile stones, EPA’s tracking and assessment of restoration progress and, as necessary, specific fede ral actions if the Bay watershed jurisdictions do not meet their targets and commitments. Alt hough not itself an element of the Chesapeake Bay TMDL, the accountability framework is bei ng established pursuant to both section 117(g)(1) of the Clean Water Act and Execu tive Order 13508, in part, to de monstrate reasonable assurance that the Chesapeake Bay TMDL allocations fo r nitrogen, phosphorus, and sediment and the jurisdictions’ water quality standards are met.

An executive summary provides an overview of the TMDL, highlighting its more important aspects. For more specific information, read ers should consult the main document, which describes each aspect of the Chesapeake Bay TMDL in detail. Finall y, for additional background and supportive material, the reader is referred to the references contained in the main document and numerous appendices.

Shawn M. Garvin, Regional Administrator U.S. Environmental Protection Agency Region 3

Judith A. Enck, Regional Administrator U.S. Environmental Protection Agency Region 2

xiv December 29, 2010Chesapeake Bay TMDL


## Acknowledgements

This document was developed through the colla borative efforts of the U.S. Environmental Protection Agency (EPA) and its seven Chesap eake Bay watershed partners—Delaware, the District of Columbia, Maryland, New York, Pe nnsylvania, Virginia, and West Virginia— principally through the Chesapeake Bay Program’s (CBP) Water Quality Goal Implementation Team (WQGIT) (formerly the Water Quality St eering Committee), its principal workgroups, and the former Nutrient Subcommittee. The CBP’s Principals’ Staff Committee made decisions on behalf of the partnership and provided policy di rection to the WQGIT. Advice, direction, and independent peer review were provided by th e CBP’s Scientific and Technical Advisory Committee (STAC), the Local Government Advi sory Committee (LGAC), and the Citizen’s Advisory Committee (CAC). Comments and reco mmendations gathered through the November– December 2009 public meetings/webinars, the m onthly webinars scheduled during 2010, and the September—November 2010 public comment period were instrumental in ensuring that the published allocations provide the most benefits to local streams and rivers and still achieve the jurisdictions’ Chesapeake Bay water quality standards.

The document resulted from the collaborative expert ise, input, feedback, and formal comments of thousands of individuals from the multitude of CBP partnering agencies and institutions, local governments, nongovernmental organi zations, businesses, many othe r involved stakeholders, and the general public. Their individual and coll ective contributions are hereby acknowledged.

Special acknowledgment is made to past a nd present members the following CBP committees: WQGIT, Principals’ Staff Committee, Manage ment Board, STAC, LGAC, CAC, Agriculture Workgroup, Forestry Workgroup, Sediment Wo rkgroup, Urban and Suburban Stormwater Workgroup, Wastewater Treat ment Workgroup, Watershed Technical Workgroup, TMDL Workgroup (formerly Reevaluation Technical Workgroup), the former Nutrient Subcommittee, Scientific and Technical An alysis and Reporting Team, Criteria Assessment Procedures Workgroup, Modeling Workgroup, Nontidal Wate r Quality Workgroup, Tidal Monitoring and Analysis Workgroup, Analytical Methods a nd Quality Assurance Workgroup, and former Monitoring and Analysis Subcommittee. Appendix A provides a detailed member listing of these committees, teams, and workgroups who were in strumental in completing the Chesapeake Bay total maximum daily load (TMDL).

Special acknowledgement is also made to the fo llowing individuals (in alphabetical order) for their contributions to the development of th e Bay TMDL, support of the development of the jurisdictions’ Phase I Watershed Implementation Pl ans (WIPs), evaluation of the draft and final Phase I WIPs, supporting public and stakeholde r outreach, responding to thousands of public comments, and publication of this document: Gr eg Allen, EPA Region 3 CBP Office; Katherine Antos, EPA Region 3 CBP Offi ce; Cheryl Atkinson, EPA Regi on 3 Water Protection Division (WPD); Seth Ausubel, EPA Region 2 Divisi on of Environmental Planning and Protection; Michael Barnes, Chesapeake Research Consorti um/CBP Office; Greg Barranco, EPA Region 3 CBP Office; Richard Batiuk, EPA Region 3 CBP Office; Benita Best-Wong, EPA Office of Water; Carin Bisland, EPA Region 3 CBP Office; Ross Brennan, EPA Office of Water; Kevin Bricke, EPA Region 2 Division of Environmen tal Planning and Protec tion; Chris Brosch, University of Maryland/CBP Office; Brian Bu rch, EPA Region 3 CBP Office; Jon Capacasa, EPA Region 3 WPD; An n Carkhuff, EPA Region 3 WPD; Peter Claggett, U.S. Geological

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Survey (USGS)/CBP Office; Jeff Corbin, EPA Re gion 3 Office of the Regional Administrator; James Curtin, EPA Office of General C ounsel; Thomas Damm, EPA Region 3 WPD; Christopher Day, EPA Region 3 Office of Regiona l Counsel; Kevin DeBell, EPA Region 3 CBP Office; Robin Dennis, NOAA/EPA Office of Research and Deve lopment; Helene Drago, EPA Region 3 WPD; Mark Dubin, University of Ma ryland/CBP Office; Jim Edward, EPA Region 3 CBP Office; Judith Enck, EPA Region 2 Regiona l Administrator; Leo E ssenthier, EPA Region 3 WPD; Barbara Finazzo, EPA Regi on 2 Division of Environmen tal Planning and Protection; Katie Foreman, University of Maryland/CBP O ffice; Kristin Foringer, Chesapeake Research Consortium/CBP Office; Debra Forman, EPA Regi on 3 WPD; J. Charles Fox, EPA Office of the Administrator; Michael Fritz, EPA Region 3 CBP Office; Elizab eth Gaige, EPA Region 3 WPD; Angie Garcia, EPA Region 3 WPD; Shawn Garv in, EPA Region 3 Regional Administrator; Kelly Gable, EPA Region 3 Office of Regional Counsel; Patricia Gleason, EPA Region 3 WPD; Peter Gold, EPA Region 3 WPD; Aaron Gorka, Chesapeake Res earch Consortium/CBP Office; Michelle Gugger, EPA Region 3 WPD; Michael Ha ire, EPA Office of Wate r; Denise Hakowski, EPA Region 3 WPD; Su zanne Hall-Trevena, EPA Region 3 WPD; James Hanlon, EPA Office of Water; Rachel Herbert, EPA Offi ce of Water; Sara Hilbrich, EP A Office of Water; Amie Howe, EPA Region 3 Office of State a nd Congressional Relations; Nan Ides, EPA Region 3 WPD; Fred Irani, USGS/CBP Office; Ruth Izraeli, EPA Re gion 2 Division of Environmental Planning and Protection; Jackie Johnson, Inters tate Commission on the Potomac River Basin/CBP Office; Jeni Keisman, University of Maryland/CBP Office; Victoria Kilbert, Chesapeake Research Consortium/CBP Office; Robert Koroncai, EPA Region 3 WPD; Caitlin Kovelove, EPA Office of Water; Amelia Letnes, EPA Office of Wate r; Mary Letzkus, EPA Region 3 WPD; Lewis Linker, EPA Region 3 CBP Office; Felix Locicero, EPA Region 2 Division of Environmental Planning and Protection; Travis Loop, EPA Region 3 CBP Office; Michael Mallonee, Interstate Commission on the Potomac River Basin/CBP Offi ce; Lori Mackey, EPA Region 3 CBP Office; David McGuigan, EPA Region 3 WPD; Evelyn M acKnight, EPA Region 3 WPD; Mike Mason, EPA Office of Water; Larry Merri ll, EPA Region 3 WPD; Linda Mi ller, EPA Region 3 Office of State and Congressional Relations; Jenny Mo lloy, EPA Region 3 CBP Office/WPD; Francis Mulhern EPA Region 3 WPD; Elizabeth Ottinger, EPA Region 3 WPD; Andrew Parker, Tetra Tech; Reggie Parrish, EPA Region 3 CBP Office; Je ffrey Potent, EPA Office of Water; Lucinda Power, EPA Region 3 CBP Office; Andrew Prugar, EPA Office of Environmental Information; Teresa Rafi, Tetra Tech; Pravin Rana, EPA Offi ce of Water; Sucharith Ravi, University of Maryland/CBP Office; Bill Richardson, EPA Re gion 3 WPD; Robert Rose, EPA Office of Water; Jennifer Sincock, EPA Re gion 3 WPD; Mike Shapiro, EPA Office of Water; Gary Shenk, EPA Region 3 CBP Office; Kelly Shenk, EP A Region 3 CBP Office; Rachel Streusand, Chesapeake Research Consortium/CBP Office; Jeff Strong, Tetra Tech; Fred Suffian, EPA Region 3 WPD; Gwen Supplee, EPA Region 3 WPD; Jeff Sweeney, University of Maryland/CBP Office; Nita Sylvester, EPA Re gion 3 CBP Office; Peter Tango, U.S. Geological Survey/CBP Office; Renee Thompson, USGS/CBP Office; Brian Trulea r, EPA Region 3 WPD; Randy Waite, EPA Office of Air and Radiation; Tom Wall, EPA Office of Water; Ping Wang, University of Maryland/CBP Office; Howard We inberg, University of Maryland/CBP Office; Steve Whitlock EPA Office of Water; Julie Wi nters, EPA Region 3 CBP Office; John Wolf, USGS/CBP Office; Robert Wood, EPA Region 3 CBP Office; Jing Wu, University of Maryland/CBP Office; Guido Yactayo, Univ ersity of Maryland/CBP Offi ce; Ning Zhou, Virginia Polytechnical and State University/CBP Office; Kyle Zieba, EPA Region 3 WPD; and Hank Zygmunt, EPA Region 3 WPD.

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Special acknowledgement of the policy direc tion and guidance provide d by Lisa Jackson, EPA Administrator; Robert Perciase pe, EPA Deputy Administrator; and Robert Sussman, Counselor to the Administrator.

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Members of the Chesapeake Bay Program’s Water Qualit y Goal Implementation Team gather in Lancaster, Pennsylvania, in April 2009 to discuss development of the Chesapeake Bay TMDL.

xviii December 29, 2010Chesapeake Bay TMDL



## SECTION 1. I NTRODUCTION

This document establishes total maximum daily loads (TMDLs) for nitrogen, phosphorus, and sediment for the Chesapeake Bay and its tidal tr ibutaries and embayments as required by section 303(d) of the Clean Water Act (CWA) and its implementing regulations at Title 40 of the Code of Federal Regulations (CFR) section 130.7. This TMDL represents the culmination of decades of collaboration among many partners and stakeholders and is the result of an analysis of water quality pollution and its solution on an unpreceden ted geographic, scientific, programmatic, and political scale. While all TMDLs are unique, this TMDL is distinguished by the magnitude of the watershed it addresses and the w ealth of science synthesized, data developed, and analyses conducted over the course of the past decades that support its conclusions.

In an effort to keep the Chesapeake Bay TMDL (Bay TMDL) document as clear and succinct as possible, discussion of the techni cal analyses and modeling that support the pollutant allocations are reasonably summarized in natu re with links provided to the more detailed technical support documentation. Because of the larg e size of the watershed and the many individual sources, load allocations (LAs) and wasteload allocations (WLA s) summarized in Section 9 are presented in greater detail in supporting appendices.

This document is organized into 11 sections as follows:

 Section 1: Clean Water Act and regulatory, statutory, and historical background of the Chesapeake Bay TMDL

 Section 2: Description of the Chesapeake Bay watershed, the Bay, and its impaired segments

 Section 3: The jurisdictions’ Ches apeake Bay water quality standards

 Section 4: The major sources of nutrients a nd sediment in the Bay, its watershed, and its airshed

 Section 5: The modeling tools used to develop the WLAs and LAs

 Section 6: How the TMDL was developed, including the allocation methodology and related considerations

 Section 7: Discussion of reasonable assurance, Bay TMDL implementation, and the Bay TMDL accountability framework

 Section 8: The evaluation of jurisdic tions’ Watershed Implementation Plans

 Section 9: The individual nitrogen, phosphorus , and sediment TMDLs for each of the 92 Bay tidal segments

 Section 10: Adaptive management appr oach to Bay TMDL implementation

 Section 11: Documentation of public participation, comments, and responses

This document also contains three additional secti ons providing: a list of references (Section 12), a glossary (Section 13), a nd a list of abbreviations (Section 14) and 24 Appendices.

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Additional supporting inform ation that is not part of this document or its appendices, can be found as follows:

 Technical documentation for each of the Ch esapeake Bay TMDL models and supporting tools—Bay airshed, land change, Scenario Builder, SPARROW, Bay watershed, Bay water quality and sediment transport, oyster filter feeder, and menhaden filter feeder—are provided via URL links in Section 5.

 Access to each of the jurisdictions’ final Ph ase I Watershed Implementation Plans (WIPs) is provided via URL in Section 7. The WIPs are part of the accountability framework meant to implement the Bay TMDL, but they ar e not an element of the Bay TMDL itself. EPA reviewed the Phase I WIPs as part of th e information used to inform its allocation decisions.

 Publicly accessible agreemen ts, documents, reports, papers, meeting summaries, correspondence, and data sets developed during the decades and more recent years leading up to the Chesapeake Bay TMDL, which were instrumental in setting the scientific, programmatic, policy, and legal foundation on wh ich the Bay TMDL is built, are listed in Appendix B with electronic access to all through the provided URLs.



### 1.1 TMDLS AND THE CWA Section 303(c) of the 1972 Clean Water Act (CWA ) requires states, including the District of Columbia, (collectively referred to as jurisdic tions) to establish water quality standards (WQS) that identify each waterbody’s designated uses an d the criteria needed to support those uses. The CWA establishes a rebuttable presum ption that all waters can attain beneficial aquatic life uses, i.e., fishable and recreational (i.e., swimmable) uses.

Section 303(d) of the CWA requires states, including the District of Columbia, to develop lists of impaired waters that fail to meet WQS set by jurisdictions even after implementing technologybased and other pollution controls. EPA’s regulat ions for implementing CWA section 303(d) are codified in the Water Quality Planning and Ma nagement Regulations at 40 CFR Part 130. The law requires that jurisdictions establish prior ity rankings and develop TMDLs for waters on the lists of impaired waters (40 CFR 130.7).

A TMDL specifies the maximum amount of a pollu tant that a waterbody can receive and still meet applicable WQS. A mathematical definiti on of a TMDL is written as the sum of the individual wasteload allocations (WLAs) for point sources, the load allocation (LAs) for nonpoint sources and natural background, and a margin of safety (MOS)[CWA section 303(d)(1)(C)]:

TMDL = Σ WLA + Σ LA + MOS

where

WLA = wasteload allocation, or the portion of the TMDL allo cated to existing and/or future point sources.

LA = load allocation, or the po rtion of the TMDL attributed to existing and/or future nonpoint sources and natural background.

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MOS = margin of safety, or the portion of the TMDL that accounts for any lack of knowledge concerning the relationship be tween effluent limitations and water quality, such as uncertainty about the relationship be tween pollutant loads and receiving water quality, which can be provided implicitly by applying conservative analytical assumptions or e xplicitly by reserving a portion of loading capacity.

The process of calculating and documenting a TMDL involves a number of tasks and— especially for a large, complex, and multijuri sdictional waterbody with multiple impairments— can require substantial effort and resources. Major tasks involv ed in the TMDL development process include the following:

 Characterizing the impaired waterbody and its watershed

 Identifying and inventorying the re levant pollutant source sectors

 Applying the appropriate WQS

 Calculating the loading capacity using appropriate modeling analyses to link pollutant loads to water quality

 Identifying the required source allocations

The Bay TMDL report presents the results of numerous analyses and model simulations designed to calculate the Bay and its tidal tribut aries and embayments’ pollutant loading capacity and documents the informational elements de scribed above. Because the Chesapeake Bay watershed is so large, and the analysis required for developing the Bay TMDL so extensive, the Chesapeake Bay TMDL and its supporting documentation consists of this report and additional supporting materials in the numerous appendice s referenced throughout the report. The Bay TMDL is also supported by an extensive li st of significant documents (Appendix B).



### 1.2 HISTORY OF THE CHESAPEAKE BAY TMDL The Chesapeake Bay watershed has been inhabite d for thousands of years, but the population started to increase si gnificantly with the arriva l of European settlers in the 1600s. Settlers began clearing forests for timber and to make room for expanding agricultural acti vities, increasing soil erosion and nutrient delivery to the Bay and its tributaries (Curtin et al. 2001; Rountree et al. 2007). As early as 1900, the oyster populati on began to decline. Throughout the 20 th century, urban development and agricultura l activities increased throughout the watershed. In the late 1970s, Maryland Senator Charles Mathias sponsored a congressionally funded, 5-year study to analyze the rapid loss of aquati c life that was affecting the Ba y. That study identified excess nitrogen and phosphorus pollution as the main source of the Bay’s degradation (USEPA 1982, 1983a, 1983b, 1983c, 1983d).



### 1.2.1 Regulatory and Ma nagement Initiatives In response to the Bay’s decline, various regul atory and management initiatives have been undertaken aimed at Bay restoration, ranging from cooperative agreements among surrounding jurisdictions to new regulatory programs and policies. Through the years, the agreements and alliances have become more formalized and inclusive to address the multitude of factors

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‐ 4 December 29, 2010 contributing to the deterioration in Chesapeake Bay water quality. The following paragraphs outline the major policy, legislative, and programma tic events that have led to the development of the Bay TMDL, including the management agreements and statutory and regulatory requirements that form the underpinning of the Bay TMDL.

1983 Chesapeake Bay Agreement In 1983 the governors of Maryland, Virginia, and Pe nnsylvania; the mayor of the District of Columbia; the chairman of the Chesapeake Ba y Commission; and EPA’ s Administrator signed the first Chesapeake Bay Agreement. In that agreement, the signatories acknowledged the decline in living resources of the Chesapeake Bay and agreed to establish the Chesapeake Executive Council (CEC) to “assess and oversee the implementation of coordinated plans to improve and protect the water quality and living resources of the Chesapeake Bay estuarine systems” (Chesapeake Bay Partnership 1983).

1987 Chesapeake Bay Agreement Faced with the need to take a more comprehens ive and coordinated approach to restoring water quality and living resources of the Chesapeak e Bay, the signatories to the 1983 agreement entered into the 1987 Chesapeake Bay Agr eement (CEC 1987). The 1987 Chesapeake Bay Agreement set priority goals and commitments, of which a key goal was to “reduce and control point and nonpoint sources of pollution to attain the water quality condition necessary to support the living resources of the Bay.” To achieve th at goal, signatories to the 1987 Bay Agreement committed to reduce the controllable nitrogen and phosphorus loads delivered to the mainstem of the Chesapeake Bay by 40 percent by 2000 and to develop a Bay-wide implementation strategy to achieve those reductions (CEC 1987).

CWA Section 117 and the Chesapeake Bay Program (CBP) In the 1987 amendments to the CWA, Congress— in section 117—authorized the formation and funding of the Chesapeake Bay Program (CBP) within EPA Region 3. Congress directed the CBP to collect and disseminate information relate d to the environmental quality of the Bay, to “coordinate state and federal effo rts to improve Bay water quality, to evaluate sediment impacts on the Bay, and to determine the impact of na tural and human-induced environmental changes on the living resources of the Bay.” 1

1991 Reevaluation A 1991 reevaluation of progress made toward achievement of the 1987 Bay Agreement’s 40 percent nutrient reduction goal led to a detailed quantification of the original narrative goal. Each major river basin by jurisdiction received a “tributary nutrient load allocation” as a “40% controllable load reduction” fo r both nitrogen and phosphorus as the principal outcome of the reevaluation (Secretary Robert Perciasepe 1992). The 1991 reevaluation also introduced several concepts still applicable in the Bay TMDL: tributary strategies (WIPs), limit of technology (everything by everyone everywhere or E3 scenar io), recognition of ai r deposition (air load allocation to tidal surface waters ), and geographic-based allocations (relative effectiveness-based allocation methodology).

1 Clean Water Act section 117 (33 United States Code [U.S.C.] 1267).Chesapeake Bay TMDL

1992 Amendments to the Chesapeake Bay Agreement
The 1991 reevaluation led to several amendments to the 1987 Chesapeake Bay Agreement in 1992, including an increased focus on the importance of the tributaries in the Bay’s restoration. The parties to the 1987 Chesapeake Bay Agreem ent were to begin by 1993 to develop and implement tributary-specific strategies to meet mainstem nutrient reduction goals, to improve water quality, and to restore living resources to the mainstem and tributaries (CEC 1992). The amendments also established a goal of expa nding the distribution of submerged aquatic vegetation (SAV) as an initial measure of progress toward the water quality and living resource goals of the 1987 Agreement.

1997 Reevaluation In 1997 the CBP conducted a year-long evaluation to assess what progress had been made toward the goal set in the 1987 Chesapeake Bay Agreement of a 40 percent reduction by 2000 in nitrogen and phosphorus delivered to the Ba y (CEC 1997). The 1997 reevaluation found that between 1985 and 1996 phosphorus loads delivered to the Bay declined by 6 million pounds annually, and nitrogen loads delivered to th e Bay declined by 29 million pounds annually. By 1996 phosphorus loads from wastewater discharger s had been reduced by 51 percent in the participating jurisdictions as a result of implem enting effluent standards, upgrading wastewater treatment plants, and banning phosphate laundry de tergents. Wastewater nitrogen loads were reduced by 15 percent by implem enting biological nut rient removal at so me major municipal wastewater treatment facilities and by upgradi ng certain industrial wastewater treatment facilities. Implementation of nutrient reduction best management practices (BMPs) reduced nonpoint source loadings of nitrogen and phosphorus to the Bay by 7 and 9 pe rcent, respectively. There was no clear trend in Bay dissolved oxygen (DO) levels, however. Although progress was made, the 1997 reevaluation report stated, “we must accelerate our efforts to close the gap on the year 2000 goal, maintain those reduced loading levels into the future and if necessary adjust the nutrient goals to help us achieve the water quality improvements needed to sustain living resources in the Bay” (CBP 1997).

1999 Integration of Cooperative and Statutory Programs In September 1999, senior water quality program managers representing the Bay watershed jurisdictions and EPA outlined the Process for Integrating the Cooperative and Statutory Programs of the Chesapeake Bay and its Tribut aries—Continuing the Watershed Partnership to Restore the Chesapeake Bay (CBP 1999). That consensus document laid the groundwork for the water quality goals and commitments within the Chesapeake 2000 Agreement. A decade in advance, it set the partnership on a course that culminated in the Bay TMDL.

Chesapeake 2000 Agreement In June 2000 the governors of Maryland, Virginia, a nd Pennsylvania; the mayor of the District of Columbia; the Administrator of EPA; and th e chairman of the Chesapeake Bay Commission signed the Chesapeake 2000 Agreement (CEC 2000). To meet the goal of “achieving and maintaining the water quality neces sary to support the aquatic livi ng resources of the Bay and its tributaries and to protect human health,” the si gnatories committed to specific actions, including:

“Continue to achieve and maintain the 40 pe rcent nutrient reduction goal agreed to in 1987.

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By 2010, correct nutrient- and sediment-related problems in the Chesapeake Bay and its tidal tributaries sufficiently to remove the Bay and the tidal portions of its tributaries from the list of impaired waters under the Clean Wate r Act. In order to achieve this:

1. By 2001, define the water quality conditions necessary to protect aquatic living resources and then assign load reductions for nitrogen and phosphorus to each major tributary;
2. By 2001, using a process parallel to that established for nutrients, determine the sediment load reductions necessary to achieve the water quality conditions that protect aquatic living resources, and assi gn load reductions for sediment to each major tributary;
3. By 2002, complete a public process to develop and begin implementation of revised Tributary Strategies to achieve and maintain the assigned loading goals;
4. By 2003, jurisdictions with tidal waters us e their best efforts to adopt new or revised WQS consistent with the de fined water quality conditions. Once adopted by the jurisdictions, EPA will expe ditiously review the new or revised standards, which are used as the basis for removing the Bay and its tidal rivers from the list of impaired waters; and

5. By 2003, work with the Susquehanna Ri ver Basin Commission and others to adopt and begin implementing strategies that prevent the lo ss of the sediment retention capabilities of the lo wer Susquehanna River dams.”

2000 Six-Jurisdiction Memorandum of Understanding In the fall of 2000, EPA, Delaware, the Di strict of Columbia, Maryland, New York, Pennsylvania, and Virginia signed a Memora ndum of Understanding (MOU) (Chesapeake Bay Watershed Partners 2000), with West Virginia joining as a signatory in June 2002, agreeing to the following:

 Work cooperatively to achieve the nutrient and sediment reduction targets necessary to achieve the goals of a clean Chesapeake Bay by 2010, thereby allowing the Chesapeake Bay and its tidal tributaries to be rem oved from the list of impaired waters.

 Provide for an inclusive, open and comp rehensive public participation process.

 Collaborate on the development and use of innova tive measures such as effluent trading, cooperative implementation mechanisms, and ex panded interstate agreements to achieve the necessary reductions.

The signatories also agreed to report annually on progress toward achie ving the goals of the agreement.

2003 Nutrient and Sediment Cap Load Allocations In 2003 EPA and its seven watershed jurisdictiona l partners established nitrogen, phosphorus, and sediment cap loads based on Bay water quality model projections of attainment of the then EPA-proposed dissolved oxygen water quality cr iteria under long-term average hydrologic conditions (Secretary Tayloe Murphy 2003). Reachi ng those cap loads was expected to eliminate

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the summer no-oxygen conditions in the deep wate rs of the Bay and excessive algal blooms throughout the Bay, tidal tributarie s and embayments (USEPA 2003c).

EPA and its watershed jurisdiction partners allocated the nitrogen and phosphorus cap loads among the major river basins by ju risdiction. Those jurisdictions w ith the highest impact on Bay water quality were assigned the highest nutrien t reductions, while jurisdictions without tidal waters received less stringent reductions because they would not realize a direct benefit from the improved water quality conditions in the Bay (USE PA 2003c). Sediment allocations were based on the phosphorus-equival ent allocations to e ach major river basin by jurisdiction (USEPA 2003c).

Although not original signatories of the Chesap eake 2000 Agreement, New York, Delaware, and West Virginia signed on as part ners in implementing the cap load s; thus, all seven Bay watershed jurisdictions were assigned allocations (Chesapeake Bay Wa tershed Partners 2000; USEPA 2003c). The final total basinwide cap loads agreed to by EPA and the seven watershed jurisdictions were 175 million pounds of nitrogen per year and 12.8 million pounds of phosphorus per year delivered to the tidal waters of the Bay (USEPA 2003c). The basinwide upland sediment cap load was 4.15 million tons per year (USEPA 2003c).

2004–2006 Tributary Strategies To achieve the nitrogen, phosphorus, and sediment cap loads, the seven watershed jurisdictions developed what became known as the Chesapeake Bay Tributary Strategies ( Table 1-1 ) (Secretary Tayloe Murp hy 2003). The tributary strategies outlined river basin-specific implementation activities to re duce nitrogen, phosphorus, and se diment pollutant loads from point and nonpoint sources sufficient to remove the Chesapeake Bay and its tidal tributaries and embayments from the Bay jurisdictions’ respective impaired waters lists. Many of the policies and procedures used in developing the Chesapeak e Bay TMDL originated with the development of the 2003 nutrient and sediment cap loads and s ubsequent development of tributary strategies.

Table 1-1. URLs for accessing the seven Chesapeake Bay watershed jurisdictions’ tributary strategies
Jurisdiction Tributary strategy URL link
Delaware http://www.chesapeakebay.net/watershedimpl ementationpla ntools.aspx?menuitem=52044
District of Columbia http://www.chesapeakebay.net/watershedimpl ementationpla ntools.aspx?menuitem=52044

Maryland http://www.dnr.state.md.us/bay/trib strat/impleme ntation_plan.html
New York http://www.dec.ny.gov/docs/water_pdf/cbaystratfinal.pdf Pennsylvania http://www.chesapeakebay.net/watershedimpl ementationpla ntools.aspx?menuitem=52044 Virginia http://www.chesapeakebay.net/watershedimpl ementationpla ntools.aspx?menuitem=52044 West Virginia http://www.wvca.us/bay/files/bay_documents/ 8_9657_WV_P otomac_Tributary_Strategy_F INAL_from_web.pdf

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2004–2005 Jurisdiction Adoption of Chesapeake Bay Water Quality Standards
In continued efforts to coordina te activities to address nitr ogen, phosphorus, and sediment-based pollution in the Bay, the tidal jurisdictions of Ma ryland, Virginia, Delaware, and the District of Columbia adopted into their respective WQS regulations the EPA-published Chesapeake Bay water quality criteria for dissolved o xygen, water clarity, SAV, and chlorophyll a , along with criteria attainment assessment pr ocedures and refined tidal water de signated uses (for details, see Section 3) (USEPA 2003a, 2003d) . EPA approved those four ju risdictions’ WQS regulations modifications pursuant to CWA section 303(c).

2007 Reevaluation Secretary Tayloe Murphy’s 2003 memorandum summarized the comprehensive set of agreements made by Bay watershed partners with regard to cap loads for nitrogen, phosphorus, and sediment; new Bay-wide and local SAV restoration goals; and a commitment to reevaluate the allocations in 2007 (Secretary Tayloe Murphy 2003). The initiation of that reevaluation at a partnership sponsored workshop in Septembe r 2005 laid the institutional groundwork for the collaborative work on the Bay TMDL (Chesa peake Bay Reevaluation Steering Committee 2005).

EPA and the seven watershed jurisdictions reeval uated the nutrient and sediment cap loads in 2007, in response to the four Bay jurisdictions revising th eir WQS regulations for the Chesapeake Bay, its tidal tributaries and emba yments in 2004-2005 (Secretary Tayloe Murphy 2003). The 2007 reevaluation found that suffici ent progress had not been made toward improving water quality to a level that indicated the mainstem Chesapeake Bay and its tidal tributaries and embayments were no longer impaired by nitrogen, phosphorus, and sediment pollution (Chesapeake Bay Reevaluation Steering Committee 2005).



### 1.2.2 Partnership Commitment to Develop the Chesapeake Bay TMDL Throughout the Bay TMDL development process, EP A has worked in close and open partnership with all seven watershed jurisd ictions, sharing decision making w ith the jurisdictions via the CBP structure described in S ection 1.3. While EPA establis hed the Bay TMDL, the seven watershed jurisdictions were esse ntial partners in the initiative, providing critical input and participating in deliberations and making key decisions affecting the development process. The seven Bay watershed jurisdictions and EPA had been building the foundation for the Chesapeake Bay TMDL since signing the Chesapeake 2000 Agreem ent, which laid out the steps necessary to put in place an appropriate framework for a future Bay TMDL, including consistent jurisdictional Chesapeak e Bay WQS (CEC 2000).

From the September 2005 reevaluation workshop to the publication of the Bay TMDL in December 2010, the seven watershed jurisdictions were actively involved in developing the Bay TMDL through participation in the CBP’s Prin cipals’ Staff Committee (PSC), Water Quality Goal Implementation Team (WQGIT), and other decision-making committees, teams, and technical workgroups (see Section 1.3.1). The full records of the meetings and conference calls of those committees, teams, and workgroups ar e accessible via the Internet—see Appendix C.

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At the October 1, 2007 meeting of the PSC, the se ven watershed jurisdictions and EPA reached consensus that EPA would establish the Bay TMDL on behalf of the seve n jurisdictions with a target date of 2025 when all necessary pollution control measures would be in place (CBP PSC 2007). Consensus within the Principals’ Staff Co mmittee means that all parties present have either agreed on this as a course of action and/or that no party obj ected to it. Table 1-2 summarizes that and the other Bay TMDL-rele vant consensus agreements reached by the partners during that meeting.

Table 1-2. Summary of Chesapeake Bay TMDL relevant actions agreed to by the CBP’s Principals’ Staff Committee during its October 1, 2007, meeting

 The Bay watershed TMDLs will be developed jointly between the six Bay watershed states, the District, and EPA and then established by EPA.

 The Water Quality Steering Committee (WQSC) will draft nutrient and sediment cap load allocations by tributary basin by jurisdiction, and the PSC will formally adopt these allocations.

 The watershed states and the District would have responsibility for further assigning loads — WLAs and LAs—to sources consistent with EPA regulations and guidance.

 These state/District suballocations (WLA/LA) would become part of the overall Bay watershed TMDLs report.

 The final publication would contain all the required document ation supporting the EPA Bay watershed TMDLs in a single, integrated publication with extensive appendices.

 EPA will provide the technical re sources/analyses required to support development of the Bay watershed TMDLs through the CBP Office staff and EPA-funded contractor support.

 The Bay watershed TMDLs must be completed and established by EPA no later than May 1, 2011.

 The CBP partners will en gage stakeholders and t he public in a more extensive structured dialogue about the tributary strategy implementation challenges before us.

 The CBP partners will focus on getting the progra ms in place by 2010 that we believe are required to achieve our water quality goals.

 The CBP partnership’s public announcement of initiation of work on the Bay watershed TMDLs will occur following the states’ submission and EPA approval of the 2008 303(d) lists in the spring 2008 time frame.

 Eight principles will guide the reevaluation e fforts by the WQSC and its workgroups (see Attachment A for more detailed version):

o Shared urgency to restore the Bay;

o Clear communication and common message;

o Focus and accelerate implementation (do no harm);

o Engage the public about the implementation challenge;

o Legal obligations will be met;

o Improving and applying the latest science;

o Flexibility of the sub-allocations within the major basins; and

o Keep healthy waters healthy.

 The WQSC will proceed forward with the responsi bility for carrying out the necessary preparation work following these eight guiding principles.

 The state/EPA Reevaluation Technical Workgr oup (RTWG) will be reconvened and operate under the direction of the WQSC.

 The RTWG was charged with responsibility for reso lving the existing technical issues in light of the desire to accelerate implementation at all scales. The WQSC will convene a parallel Implementation Workgroup and charge this group wi th the responsibility for ensuring that the reevaluation and TMDL development process results in acceleration of ongoing tributary strategy implementation.

Source: CBP PSC 2007

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### 1.2.3 President’s Chesapeake Bay Executive Order On May 12, 2009, President Barack Obama i ssued the Chesapeake Bay Protection and Restoration Executive Order 13508, which calls for the federal government to lead a renewed effort to restore and protect the Chesapeake Bay and its watershed. Critical among its directives

were:

 Establish a Federal Leadership Committee to oversee the development and coordination of reporting, data management and other activitie s by agencies involved in Bay restoration.

 Require involved agencies to prepare and s ubmit reports with recommendations on a wide range of Bay issues (EPA -HQ-OW-2009-0761; FRL-8978-8).

 Require the Federal Leadership Committee to develop a Strategy for Protecting and Restoring the Chesapeake Bay by May 2010 ( http://executiveorder.chesapeakebay.net/ ).

 Require the Federal Leadership Committee to publish an annual Chesapeake Bay Action Plan describing how federal funding proposed in the President’s budget will be used to protect and restore the Chesapeake Ba y during the upcoming fiscal year.

 Require federal agencies to consult extensively with Bay watershed jurisdictions in preparing their reports.

Pursuant to the Executive Order, on May 12, 2010, the Federal Leadership Committee—led by the EPA Administrator and secretaries from the Departments of Agriculture, Commerce, Defense, Homeland Security, Interior, Trans portation, and others—issued its coordinated strategy for restoring the Chesapeake Bay (FLCCB 2010). That strategy sets measurable goals for improving environmental conditions in the Bay for the following:

 Clean water

 Habitat

 Fish and wildlife

 Land and public access

Other supporting strategies address citizen stewardship, climate change, science, and implementation and accountability. A key element of the approach for meeting water quality goals was the development of this TMDL for the Chesapeake Bay (FLCCB 2010).

Parallel to the issuance of the Executive Order, the jurisdictions and the federal government committed to implement all necessary measures for restoring water quality in the Bay by 2025 and to meet specific milestones every 2 year s (FRL-8955-4; Clean Water Act section 303(d): Preliminary Notice of Total Maximum Daily Load (TMDL) Development for the Chesapeake Bay). To that end, EPA is developing an accountability framework to guide the overall restoration effort and to link it to impl ementation of the Chesapeake Bay TMDL. The accountability framework, which is di scussed in more detail in S ection 7, includes four elements:

 Watershed Implementation Plans (WIPs)

 Two-year milestones to dem onstrate restoration progress

 EPA’s commitment to track and assess progress

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 Federal actions if the Bay wa tershed jurisdictions fail to meet expectations such as developing sufficient WIPs, effectively implem enting their WIPs, and/or fulfilling their 2- year milestones



### 1.3 BAY TMDL PROCESS, PARTNER COORDINATION AND RESPONSIBILITIES EPA Region 3 is the lead federal office res ponsible for developing the Chesapeake Bay TMDL, with the Water Protection Division (WPD) having the lead responsibilit y within the Regional Office. In developing this TM DL, WPD coordinated efforts w ith the Chesapeake Bay Program Office, Air Protection Division, Office of Regional Counsel, Offi ce of State and Congressional Relations, Office of Public Affairs, and Office of the Regional Administrator (all within EPA Region 3), EPA Region 2 (Division of Environmental Planning and Restoration and Office of the Regional Administrator), and EP A Headquarters (Office of Water, Office of General Counsel, Office of Air and Radiation, and Office of the Administrator). Throughout the Bay TMDL development process, EPA worked in close a nd open partnership with all seven watershed jurisdictions, numerous federal agency partners, and a diverse array of other partners and stakeholders through the CBP partnership. This se ction describes the different elements of the CBP organizational structure and provides ad ditional descriptions of the roles and responsibilities of the various entities and stakeholde rs involved in developing the Chesapeake Bay TMDL.



### 1.3.1 CBP Partnership and Organizational Structure The CBP is a unique regional partnership that includes Maryland, Pennsylvania, Virginia, the District of Columbia, the Chesapeake Bay Commission, EPA, federal agencies, and participating advisory groups. The headwater states of Delawa re, New York, and West Virginia participate as full partners on issues related to water quality. Each of the CBP partners agrees to use its own resources to implement projects and activities that advance Bay and watershed restoration.

The partnership defines its collective actions through formal, voluntary agreements and provides general policy direction through consensus docum ents, typically called directives. The CBP works through a series of Goal Implementation Teams with oversight provided by the CBP’s Management Board. Extensive documentation of the CBP structure and governance is provided in Chesapeake Bay Program Governance—Managing the Partnership for a Restored and Protected Watershed and Bay (CBP 2009). Figure 1-1 shows th e CBP organizational chart.

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Source: CBP 2009

Figure 1-1. CBP’s organizational structure.

Chesapeake Executive Council The top executive of each of the signatories of the Chesapeake 2000 Agreement (state governors, the District of Columbia ma yor, EPA Administrator, and Chesapeake Bay Commission Chair), form the Chesapeake Executive C ouncil (CEC), which meets annually to set basinwide policies and the future directions for the CBP. Delaware , New York, and West Vi rginia participate in CEC meetings and have full input status on all water quality-related matters. Principals’ Staff Committee (PSC) members serve as advisors to their respecti ve CEC members. The CEC has played a pivotal role in de veloping the Bay TMDL by signing the Chesapeake 2000 Agreement and subsequent directives and by setting the partne rship on a well-defined, 10-year path directly supporting development of the Bay TMDL (CEC 2000, 2003, 2005).

Federal Leadership Committee To bring the full weight of the federal governme nt to address the Chesapeake’s challenges, President Obama issued Executive Order 13508 on Chesapeake Bay Protection and Restoration and established the Federal Leadership Committee, which is chaired by the Administrator of the U.S. Environmental Protection Agency and include s senior representative s from the departments of Agriculture, Commerce, Defense, Homela nd Security, Interior, and Transportation.

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‐ 13 December 29, 2010 Principals’ Staff Committee The Principals’ Staff Committee (PSC) provide d policy and programmatic direction to the Management Board on the development and a doption of the Chesapeake Bay nutrient and sediment targets and allocations for the Bay TMDL (Figure 1-1). The PSC is composed of cabinet-level representatives from each of th e seven watershed jurisdictions, EPA Region 3’s Regional Administrator, senior federal agen cy executives, the Chesapeake Bay Commission executive director, and the director of the CBP Office. The Regional Administrator of EPA Region 3 currently chairs the PSC. The Citizens, Local Governments, and the Scientific and Technical advisory committ ees all advise the PSC.

Management Board PSC members provided policy and program directi on to the Management Board which, in turn, provided strategic planning, priori ty setting, and operational guidan ce and direction to the Water Quality Goal Implementation Team (WQGIT) during the development of the Bay TMDL (Figure 1-1). The Management Board is compos ed of senior policy representatives from the seven watershed jurisdictions, the Chesapeake Ba y Commission, the nine core federal agency partners, 2 and the chairs of the Citizens, Local Governments, and the Scientific and Technical advisory committees. The Management Board direct s and coordinates the efforts of the six Goal Implementation Teams and Action Teams. The director of the CBP Office chairs the Management Board, and the CBP Office provides for the staff to support the work of all the Goal Implementation Teams and workgroups. Staffing fo r the three advisory committees is supported by EPA through cooperative agreements with nonprofit organizations.

Water Quality Goal Implementation Team The WQGIT’s purpose is to support efforts to reduce and cap the nitrogen, phosphorus, and sediment loads entering the Bay and to ensure that such reductions are maintained over time. It is composed of the members of the former Wate r Quality Steering Committee and the former Nutrient Subcommittee. The WQGIT provided advi ce and guidance to EPA related to the draft target loads and allocations before they were brought to the PSC. The WQGIT consists of senior water program managers from each of the seve n Bay watershed jurisdictions, EPA Headquarters and Regions 2 and 3, the Chesapeake Bay Commission, the Susquehanna River Basin Commission, and the Interstate Commission on th e Potomac River Basin. The WQGIT provided technical direction to the Wate rshed Technical, Agriculture, Forestry, Wastewater Treatment, Sediment, and Urban Stormwater workgroups.

Watershed Technical Workgroup The Watershed Technical Workgroup was create d to provide a forum for communication among the Bay watershed jurisdictions and other CBP partic ipants on technical issues originally related to tributary strategy development, tracking a nd reporting. Members of th e Watershed Technical Workgroup include technical st aff and mid-level managers from the seven watershed jurisdictions, EPA, and point s ource and environmental stakehol der groups. For the Chesapeake

2 The Natural Resources Conservation Service, U.S. Forest Service, National Oceanic and Atmospheric Administration, U.S. Geological Survey, National Park Service, U.S. Fish and Wildlife Service, U.S. Army Corps of Engineers, U.S. Department of Defense, and EPA.Chesapeake Bay TMDL

Bay TMDL, the workgroup provided review and overs ight in regards to application of the Bay Watershed Model.

Pollutant Source Workgroups The Agricultural Workgroup coordinated and ev aluated agricultural nu trient and sediment reduction measures throughout the ju risdictions and resolved issues related to tracking, reporting, and crediting conservation practices.

The Forestry Workgroup provided information on the effectiveness of different riparian forest buffer restoration and other forest management practices.

The Wastewater Treatment Workgroup provi ded a formal means of communication among federal agencies, state agencies/jurisdictions, and wastewater treatment facility owner/operators.

The Sediment Workgroup provided t echnical and policy-related assistance to the CBP partners in setting the sediment allocations.

The Urban Stormwater Workgroup provided input re lated to all aspects of stormwater nutrient and sediment loads and management practices.

Science, Technical Analysis, and Reporting Team—Criteria Assessment Protocols Workgroup The Criteria Assessment Protocols Workgroup had the lead responsibility for ensuring coordinated assessment of all Chesapeake Bay, tida l tributary and embayment waters related to the four Bay jurisdictions’ lis ting and delisting under CWA sec tion 303(d). The workgroup also had the lead in developing, reviewing, and recommending to the WQGIT amendments to the original 2003 Chesapeake Bay water quality criteria published by EPA.

Science, Technical Analysis, and Reporting Team—Modeling Workgroup The Modeling Workgroup, formerly the Modelin g Subcommittee and now under the Science, Technical Analysis, and Reporting (STAR) t eam, oversaw the devel opment, calibration, verification, and management application of th e suite of computer-bas ed Bay models that supported the development of the Bay TMDL. The models allowed managers to estimate the pollutant load reductions needed to achieve WQ S and to assess the potential of different management scenarios to achieve th e needed pollutant load reductions.

Scientific and Technical Advisory Committee
The Scientific and Technical Advisory Committee (STAC) is composed of scientists representing a diverse range of disciplines from federal agenci es and academic institutions in the seven watershed jurisdictions. ST AC provides scientific and tec hnical guidance and independent scientific peer review to the CBP on measures to restore and pr otect the Chesapeake Bay. STAC activities related to the Bay TMDL included indepe ndent scientific peer reviews of all the Bay models (watershed, land change, es tuarine water quality, estuarine sediment transport, estuarine filter feeder), Bay criteria assessment procedures, and land use data, and reviewing and commenting on the draft Bay TMDL.

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‐ 15 December 29, 2010 Local Governments Advisory Committee The Local Governments Advisory Committee (L GAC) is a body of locally elected officials appointed by the governors of Maryland, Pennsylvania, Virginia, and the mayor of the District of Columbia. The LGAC was established to prom ote the role of local governments in Bay restoration efforts and develop strategies that ultimately broade n local government participation in the CBP. The LGAC was directly involved in developing the Bay TMDL in the following ways: ensured the direct involvement of local el ected officials in the decision-making processes, helped establish the local Wa tershed Implementation Plan (WIP) pilots in 2010 (before development of the Phase II WIPs starting in 201 1), and helped inform the thousands of local governments across the watershed about the Bay TMDL.

Citizen’s Advisory Committee The Citizens Advisory Committee (CAC) provides advice to the CEC, the PSC, the Management Board, and all the Goal Implementation Teams as needed in implementing the Chesapeake Bay Agreement. The CAC directly assisted the Bay TMDL development process by providing detailed recommendations on how to engage th e nongovernmental components of the larger Bay watershed community and placi ng a strong focus on ensuring full accountability during the development and throughout the long-t erm implementation of the Bay TMDL.

Appendix A provides the membership lists of a ll the above described committees, teams, and workgroups at the time of publication of the Bay TMDL, fully acknowledging their individual and collective contributions.



### 1.4 LEGAL FRAMEWO RK FOR THE CHESAPEAKE BAY TMDL

1.4.1 What is a TMDL? As discussed more fully in Section 1.1, a TMDL specifies the maximum amount of a pollutant that a waterbody can receive and still meet appl icable WQS. Allocations to point sources are called wasteload allocations or WLAs, while allo cations to nonpoint sources are called load allocations or LAs. A TMDL is the sum of th e WLAs (for point sour ces), LAs (for nonpoint sources and natural background) (40 CFR 130.2), and a margin of safety (CWA section 303(d)(1)(C)). Section 303(d) requires that TMDLs be establis hed for impaired waterbodies “at a level necessary to implement the applicable [WQS].” 3

TMDLs are “primarily informational tools” that “s erve as a link in an implementation chain that includes federally regulated point source controls , state or local plans for point and nonpoint source pollutant reduction, and asse ssment of the impact of such measures on water quality, all to the end of attaining water quality goals for the nation’s waters.” 4 Recognizing a TMDL’s role as a vital link in the implementation chain, federa l regulations require that effluent limits in NPDES permits be “consistent with the assumptions and requirements of any available WLA” in an approved TMDL. 5

3 33 U.S.C. 1313(d)(1)(C).
4 Pronsolino v. Nastri, 291 F.3d 1123, 1129 (9 th Cir. 2002).
5 40 CFR 122.44(d)(1)(vii)(B).Chesapeake Bay TMDL

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‐ 16 December 29, 2010 In addition, before EPA establishes or approves a TMDL that allocates pollutant loads to both point and nonpoint sources, it determines whethe r there is reasonable assurance that the nonpoint source LAs will, in fact, be achieved and WQ S will be attained (USEPA 1991b). If the reductions embodied in LAs are not fully achie ved, the collective reduc tions from point and nonpoint sources will not result in attainment of the WQS.

The Bay TMDL will be implemented using an accountability framework that includes the jurisdictions’ WIPs, 2-year mile stones, EPA’s tracking and asse ssment of restoration progress and, as necessary, specific federal actions if the Bay juri sdictions do not meet their commitments. The accountability framework is being established, in part, to demonstrate that the Bay TMDL is supported by reasonable assurance. The accountability framework is also being established pursuant to CWA s ection 117(g)(1). Section 117(g) of the CWA directs the EPA Administrator to “ensure that management pl ans are developed and implementation is begun...to achieve and maintain...the nutrient goals of th e Chesapeake Bay Agreement for the quantity of nitrogen and phosphorus entering the Chesapeake Ba y and its watershed, [and] the water quality requirements necessary to restore living resources in the Chesapeake Bay ecosystem.” 6 In addition, Executive Order 13508 directs EPA and other federal agencies to build a new accountability framework that guid es local, state, and federal wa ter quality restoration efforts. The accountability framework is designed to he lp ensure that the Bay’s nitrogen, phosphorus, and sediment goals, as embodied in the Ch esapeake Bay TMDL, are met. While the accountability framework informs the TMDL, section 303(d) does not require that EPA “approve” the framework per se , or the jurisdictions’ WIPs that constitute part of that framework.



### 1.4.2 Why is EPA establishing this TMDL?
In 1998, data showed the mainstem and tidal tr ibutary waters of the Chesapeake Bay to be impaired for aquatic life resources. EPA determined that the mainstem and tidal tributary waters of the Chesapeake Bay must be placed on Virginia ’s section 303(d) list. EPA therefore added the mainstem of the Chesapeake Bay to Virginia’s final section 303(d) list. As described in Section 2, each tidal river, tribut ary, embayment, and other tidal waterbody that is part of the Chesapeake Bay TMDL is included on a jurisdiction’s section 303(d) list.

EPA established the Chesapeake Bay TMDL pursua nt to a number of existing authorities, including the CWA and its implementing regulati ons, judicial consent de crees requiring EPA to address certain impaired Chesapeake Bay and tidal tributary and embayment waters, a settlement agreement resolving litigation brought by th e Chesapeake Bay Founda tion, the 2000 Chesapeake Agreement, and Executive Order 13508. In esta blishing the Bay TMDL, EPA acted pursuant to the consensus direction of the Chesapeake Execu tive Council’s PSC and in partnership with each of the seven Chesapeake Bay watershed jurisdictions.

The CWA provides EPA with ample authority to establish the Chesapeake Bay TMDL. CWA section 117(g)(1) provides that “[t]he Administrato r, in coordination with other members of the [CEC], shall ensure that management plans are developed and implementation is begun by signatories to the Chesapeake Bay Agreement to achieve and maintain [among other things] the

6 Clean Water Act section 117(g)(1)(A)-(B), 33 U.S.C. 1267(g)(1)(A)-(B).Chesapeake Bay TMDL

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‐ 17 December 29, 2010 nutrient goals of the Chesapeake Bay Agreemen t for the quantity of nitrogen and phosphorus entering the Chesapeake Bay and its watershed [and] the water quality requirements necessary to restore living resources in the Chesapeake Bay ecosystem.” Because it establishes the Bay and tidal tributaries’ nutrient a nd sediment loading and allocati on targets, the Chesapeake Bay TMDL is itself such a “management plan.” In addition, the Bay TMDL’s loading and allocation targets both inform and are informed by a larger set of federal and state management plans being developed for the Bay, including the Bay wate rshed jurisdictions’ WIPs and the May 2010 Strategy for Protecting and Restoring the Chesapeake Bay (FLCCB 2010).

CWA section 303(d) requires jurisdictions to establish and submit TMDL s to EPA for review. Under certain circumstances, EPA also has the au thority to establish TMDLs. The circumstances of this TMDL do not necessarily identify the ou ter bounds of EPA’s auth ority. However, where – as here – impaired waters have been identified on jurisdictions’ section 303(d ) lists for many years, where the jurisdictions in question decided not to establish their own TMDLs for those waters, where EPA is establishing a TMDL for those wate rs at the direction of, and in cooperation with, the jurisdictions in question, and where those waters are part of an interrelated and interstate water system like the Chesapeake Bay that is impaired by pollutant loadings from sources in seven different jurisdictions, CWA section 303(d) authorizes EPA to establish that TMDL 7

. On May 12, 2009, President Barack Obama signed Executive Order 13508— Chesapeake Bay Protection and Restoration . The Executive Order’s overarching goal is “to protect and restore the health, heritage, natural re sources, and social and economic value of the Nation’s largest estuarine ecosystem and the natural sustainabilit y of its watershed.” The Executive Order says the federal government “should lead this effort ” and acknowledges that pr ogress in restoring the Bay “will depend on the support of state and local governments.” To that end, the Executive Order directs the lead federal agencies, including EPA, to work in close collaboration with their state partners. To protect and re store the Chesapeake Bay and its tidal tributaries, the President directed EPA to “make full use of its author ities under the [CWA].” In establishing the Bay TMDL, EPA is doing no more—or less—than making full use of its CWA authorities to lead a collaborative and effective federal and state effort to meet the Bay’s nutrient and sediment goals.

A number of consent decrees, memoranda of unde rstanding (MOUs), and settlement agreements provide additional support for EPA’s decisi on to establish the Chesapeake Bay TMDL addressing certain waters identifi ed as impaired on the Maryland, Virginia, and the District of Columbia’s 1998 section 303(d) lists and on the Delaware 19 96 section 303(d) list. EPA established the Chesapeake Bay TMDL consis tent with those consent decrees, MOUs, and settlement agreements, described below.

Virginia–EPA Consent Decree The American Canoe Association, Inc., and the American Littoral Society filed a complaint against EPA for failing to comply with the CWA, including section 303(d), regarding the TMDL program in the Commonwealth of Virginia. A consent decree signed in 1999 resolved the litigation. 8 The consent decree includes a 12-year sc hedule for developing TMDLs for impaired

7 Dioxin/Organochlorine Center v. Clarke , 57 F.3d 1517 (9 th Cir. 1995); Scott v. City of Hammond , 741 F.2d 992 (7 th Cir. 1984); American Canoe Assn. v EPA , 54 F.Supp.2d 621 (E.D.Va. 1999).
8 American Canoe Association v. EPA , 98cv979 (June 11, 1999).Chesapeake Bay TMDL

segments identified on Virginia’s 1998 section 303(d) list. The consent decree requires EPA to establish TMDLs for those waters, by May 1, 2011, if Virginia fails to do so according to the established schedule. Virginia has requested th at EPA establish TMDLs for the nutrient- and sediment-impaired tidal portions of the Chesapeake Bay and its tributaries and embayments in accordance with the Virginia consent decree sc hedule (CBP PSC 2007). Table 1-3 provides a list of the Virginia consent decree waters that we re addressed by the Chesapeake Bay TMDLs for nitrogen, phosphorus, and sediment.

Table 1-3. Virginia consent decree (CD) waters impaired for dissolved oxygen (DO) and/or nutrients addressed by the Chesapeake Bay TMDL Waterbody Name CD Segment ID Chesapeake Bay Segment ID CD Impairment Bailey Bay, Bailey Creek – Tidal VAP-G03E JMSTF1 DO
Broad Creek VAT-G15E ELIPH, WBEMH,SBEMH, EBEMH DO

Chesapeake Bay Mainstem Narrative a CB5MH, CB6PH, CB7PH Nutrients Chesapeake Bay Mainstem VACB-R 01E CB5MH, CB6PH, CB7PH DO
Elizabeth River – Tidal Narrative b ELIPH, WBEMH,SBEMH, EBEMH Nutrients

Hungars Creek VAT-C14R CB7PH DO
James River – Tidal Narrative c JMSTF2, JMSTF1, JMSOH, JMSMH, JMSPH Nutrients

King Creek VAT-F27E YRKPH DO Mattaponi River – Tidal Narrative d MPNTF, MPNOH Nutrients Messongo Creek VAT-C10E POCMH DO
North Branch Onancock Creek VAT-C11E CB7PH DO Pagan River VAT-G11E JMSMH DO Pamunkey River – Tidal Narrative e PMKTF, PMKOH Nutrients Queen Creek VAT-F26E YRKMH DO Rappahannock River Narrative f RPPMH Nutrients Rappahannock River VAP-E 25E RPPMH Nutrients Rappahannock River VAP- E25E RPPMH DO Rappahannock River VAP-E 26E RPPMH Nutrients Rappahannock River VAP- E26E RPPMH DO
Thalia Creek VAT-C08E LYNPH DO
Williams Creek VAN-A30E POTMH DO
York River Narrative g YRKMH, YRKPH Nutrients
York River VAT-F27E YRKPH DO

Source: American Canoe Association v. EPA , 98cv979 (June 11, 1999). Notes: a = Chesapeake Bay Mainstem (VACB-R01E) impaired for nutrients b = Elizabeth River (VAT-G15E) impaired for DO, nutrients c = James River (VAP-G01E, VAP-G03E, VAP-G02E, VAP-G 04E, VAP-G11E, and VAP-G15E) impaired for nutrients d = Mattaponi River (VAP-F24E and VAP-F25E) impaired for nutrients e = Pamunkey River (VAP-F13E and VAP-F14E) impaired for DO, nutrients f = Rappahannock River (VAP-E24E) impaired for DO g = York River (VAT-F26E) impaired for nutrients

1

‐ 18 December 29, 2010Chesapeake Bay TMDL

1

‐ 19 December 29, 2010 District of Columbia–EPA Consent Decree In 1998 Kingman Park Civic Association and others filed a similar suit against EPA. 9 The lawsuit was settled through the entry of a consent decree requi ring EPA to, among other things, establish TMDLs for the District of Columbia’s portions of the tidal Potomac and tidal Anacostia rivers if not established by the Dist rict of Columbia by a certain date.

The impairment of the District of Columbia’s portion of the upper tidal Potomac River by low pH is directly related to the Chesapeake Bay wa ter quality impairments because the low pH is a result of excess nutrients causing algal blooms in the tidal river. Establishing a tidal Potomac River pH TMDL is directly li nked to establishing the Chesapeake Bay TMDL because of their common impairing pollutants (nitrogen and phos phorus) and the hydrologic connection between the District’s portion of the ti dal Potomac River and the Chesapeake Bay. EPA and the Kingman Park plaintiffs jointly sought, and received on February 12, 2008, a formal extension of the District of Columbia TMDL Consent Decree so that EPA could complete the Potomac River pH TMDL on the same schedule as the Chesapeake Bay TMDL. 10 The District of Columbia requested that EPA establish the pH TMDL for the District’s por tion of the tidal Potomac River (CBP PSC 2007). Table 1-4 provides a list of the District’s consent decree waters that were addressed by the Chesapeake Bay TMDL s for nitrogen, phosphorus, and sedim ent.
In addition, Anacostia Riverkeeper and Friends of the Earth filed suit against EPA challenging more than 300 TMDLs for the District of Columbia, including the Anacostia River TMDLs, because the TMDLs were not expressed as dail y loads. On May 25, 2010, the District Court for the District of Columbia ordered the vacatur of the District of Columbia’s TMDL for pH for the Washington Ship Channel, with a stay of vacatur until May 31, 2011. 11 With publication of the Bay TMDL, the Washington Ship Channel pH impairment has been addressed and the pH TMDL for the Ship Channel approved by EPA on December 15, 2004 has been superseded.

Table 1-4. District of Columbia consent decree (CD) waters impaired for pH addressed by the Chesapeake Bay TMDL

Waterbody Name CD Segment ID Chesapeake Bay Segment ID CD Impairment Washington Ship Channel DCPWC04E_00 POTTF_DC pH
Middle Potomac River DCPMS00E POTTF_DC pH

Source: Kingman Park Civic Association v EPA , 98cv00758 (June 13, 2000).

Delaware–EPA Consent Decree
In 1996 the American Littoral Societ y and the Sierra Club filed a suit against EPA to ensure that TMDLs were developed for waters on Delaware ’s 1996 section 303(d) list, one of which is a tidal Bay segment (Upper Nanticoke River). The pa rties entered into a c onsent decree resolving the lawsuit. 12 The consent decree required EPA to esta blish TMDLs if Delaware failed to do so within the 10-year TMDL development schedule. Although Delaware established TMDLs for the

9 Kingman Park Civic Association v EPA , 98cv00758 (June 13, 2000).
10 Kingman Park Civic Association v. EPA , 98cv00758 (Order February 12, 2008). 11 Anacostia Riverkeeper et al v. Jackson , 1:2009cv00098 (D.DC)( Mem. and Order May 25, 2010)

12 American Littoral Society, et al. v EPA, et al. , 96cv591 (D.Del. 1997).Chesapeake Bay TMDL

1

‐ 20 December 29, 2010 one listed tidal Bay segment (DE DNREC 1998), the TMDLs were established to meet prior WQS and are insufficient to attain Chesapeake Bay WQS.

Maryland–EPA MOU In 1998 Maryland and EPA Region 3 entered into an MOU that, among other things, established a 10-year schedule for addressing waters on Maryland’s 1998 section 303(d) list, with completion by 2008 (MDE 1998). Because of funding constraints, the complexity of some TMDLs, and limited staff resources, Maryland determin ed that it would not be able to address all 1998 listed waters by 2008. Further, the Chesap eake 2000 Agreement established a goal of meeting water quality standards in the Chesap eake Bay by 2010 (CEC 2000). Many of the waters on Maryland’s 1998 section 303(d) list were open waters of the Bay or tidal tributaries and embayments to the Bay. Maryland determined th at developing TMDLs for those tidal waters before the deadline established by the MOU, as would be required under th e schedule established in 1998, “would undermine the spirit of the agreemen t” because of a lack of integration between the CBP partnership and Maryland efforts (M DE 2004). Therefore, Maryland decided to postpone development of TMDLs for Maryland’s listed Chesapeake Bay and its tidal tributary and embayment waters until the two programs could coordinate efforts.

In September 2004, Maryland and EPA Region 3 ente red into a revised MOU that extended the schedule for TMDL development to 13 years (by 2011) (MDE 2004). Although neither Maryland nor EPA is under a consent decree for establishing TMDLs for Maryland waters, the state has requested that EPA develop the TM DLs for the Maryland portion of the Chesapeake Bay and tidal tributaries and embayments im paired by excess nitrogen, phosphorus, and sediment as recognized in the MOU between Maryland and EPA (CBP PSC 2007).

Chesapeake Bay Foundation Settlement Agreement In January 2009, the Chesapeake Bay Foundation a nd others filed suit against EPA in U.S. District Court for the District of Columbia (1:09-cv-00005-CKK) alleging, among other things, that EPA had failed to carry out nondiscretiona ry duties under CWA section 117(g) designed to restore and preserve the Chesapeake Bay. In Ma y 2010, EPA signed a settlement agreement with the plaintiffs promising to take a number of actions to restore and preserve the Bay. In particular, EPA promised that by December 31, 2010, it would establish a TMDL for those segments of the Chesapeake Bay impaired by nitrogen, phosphorus, and sediment. EPA is establishing this TMDL, in part, to meet that commitment.Chesapeake Bay TMDL



## SECTION 2. W ATERSHED AND IMPAIRMENT DESCRIPTION

This section provides a general description of the watershed a nd the impairments addressed in the Chesapeake Bay TMDL. Section 2.1 provides a description of the basic history, geography, land uses, and recent development patterns and tre nds. Section 2.2 presents the scope of the Bay TMDL including the parameters of concern, the specific impairment listings addressed, and the Bay TMDL segmentation.



### 2.1 GENERAL WATE RSHED SETTING The Chesapeake Bay watershed includes parts of six states—Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia—and the entire District of Columbia (collectively, the jurisdictions). The Chesapeake Bay proper is a pproximately 200 miles lo ng, stretching from Havre de Grace, Maryland, to Norf olk, Virginia. It varies in wi dth from about 3.4 miles near Aberdeen, Maryland, to 35 miles near the mouth of the Poto mac River. The easternmost boundary of the Chesapeake Bay with the Atlantic Ocean is represented by a line between Cape Charles and Cape Henry. Including its tidal tr ibutaries and embayments, the Chesapeake Bay encompasses approximately 11,684 miles of shoreline, a length longer than the entire West Coast of the United States.

About half of the Bay’s water volume consists of saltwater from the A tlantic Ocean. The other half is freshwater that drains into th e Bay from its 64,000-square-mile watershed ( Figure 2-1 ). Ninety percent of the freshwater is delivered fro m five major rivers: the Susquehanna (which is responsible for about 50 percent) , Potomac, James, Rappahannock, and York rivers. In all, the watershed contains more than 10,000 streams and rivers that eventually flow into the Bay.

Runoff from the Bay’s enormous watershed flow s into an estuary with a surface area of 4,500 square miles resulting in a land-to -water ratio of 14 to 1. That larg e ratio is one of the key factors in explaining why the drainage area has such a significant influence on water quality in the Bay.

Although the Chesapeake Bay is entirely within the Atlantic Coastal Plain, its watershed includes parts of the Piedmont and Appalachian provinces . The waters that flow into the Bay have different chemical characteristics, dependi ng on the geology from which they originate ( Figure 2-2 ).

2

‐ 1 December 29, 2010Chesapeake Bay TMDL

Figure 2-1. The Chesapeake Bay watershed with major rivers and cities.

2

‐ 2 December 29, 2010Chesapeake Bay TMDL

Source: USGS WRIR 00-424

Figure 2-2. Hydrogeomorphic regions of the Chesapeake Bay watershed.

2

‐ 3 December 29, 2010Chesapeake Bay TMDL

The Atlantic Coastal Plain is a flat, lowland area with a maximum elevation of about 300 feet. It is supported by a bed of crystalline rock, cove red with southeasterly dipping wedge-shaped layers of relatively unconsolidated sand, cla y, and gravel. Water passing through the loosely compacted mixture dissolves many of the minerals . The most soluble elements are iron, calcium, and magnesium. The coastal plain extends from the e dge of the continental shelf, to the east, to a fall line that ranges from 15 to 90 miles west of the Chesapeake Bay. The fall line, which is the location where free flowing streams enter tidal waters, forms the boundary between the Piedmont Plateau and the coastal plain. Waterfalls and rapi ds clearly mark this line, which is close to Interstate 95. At the fall line, the elevation ri ses to 1,100 feet.

The Piedmont Plateau extends from the fall line in the east to the Appala chian Mountains in the west. The area is divided into two geologically distinct regions by Parrs Ridge, which traverses Carroll, Howard, and Montgomery counties in Mary land and adjacent counties in Pennsylvania. Several types of dense, crystall ine rock—including slates, schist s, marble, and granite—compose the eastern side of the Piedmont Plateau. That variety results in a very diverse topography. Rocks of the Piedmont tend to be impermeable, and wate r from the eastern side is low in calcium and magnesium salts. The western side of the Piedmont consists of sandstones, shales, and siltstones, layered over by limestone. The limestone bedroc k contributes calcium and magnesium to its water, making it hard. Waters from the western side of Parrs Ridge flow into the Potomac River, one of the Chesapeake Bay’s largest tributaries.

The Appalachian Province covers th e western and northern part of the watershed and is rich in coal and natural gas deposits. Sandstone, siltston e, shale, and limestone form the bedrock. Water from that province flows to the Chesapeak e Bay mainly via the Susquehanna River.

Earliest evidence of human inhabi tants in the Bay watershed is of hunter-gatherers as long as 10,000 years ago. Native Americans began cultivati ng crops and settling in villages throughout the area around 1,000 years ago. European settlement less than 500 hundred years ago began a period of transformation of forests into fa rmland, while today many of those lands are undergoing retransformations into urban and suburban lands.

Over the past hundreds of years, forest cleari ng and urban development have resulted in the following land use breakdown in the watershed: 69 percent wooded/open, 22 percent agriculture, 7 percent developed, and 2 percen t open water and extractive ( Figure 2-3 ).
From 1950 through 2008, the Bay watershed ’s popul ation doubled, increasing from 8.3 million to 16.8 million. The 8-year period from 2000 to 2008 witnessed population growth of approximately 7 percent from 15.7 million. T oday, nearly 17 million people live in the watershed. According to census data, the wa tershed’s population is growing by about 157,000 per year. Projections through 2030 are for the population to reach approximately 20 million ( Figure 2-4 ).

2

‐ 4 December 29, 2010Chesapeake Bay TMDL

Source: Irani and Claggett 2010

Figure 2-3. Chesapeake Bay watershed land cover.

2

‐ 5 December 29, 2010Chesapeake Bay TMDL

Source: CBP Office Bay Barometer 2009

Figure 2-4. Reported and projected human population growth in the Chesapeake Bay watershed 1950–2030.



### 2.2 CHESAPEAKE BAY TMDL SCOPE The Chesapeake Bay TMDL is the largest, mo st complex TMDL in the country, covering a 64,000-square-mile area across seven jurisdictions. EPA established a federal TMDL for the tidal segments of the Chesapeake Bay and its tidal tr ibutaries and embayments that are impaired for aquatic life uses due to excessi ve loads of nutrients (nitroge n and phosphorus) and sediment and listed on the four tidal Bay jurisdictions’ respec tive CWA 2008 section 303(d) lists of impaired waters. The Bay TMDL also alloca tes loadings of nitrogen, phos phorus, and sediment to sources contributing those pollutants in all seven juri sdictions in the Bay watershed—Delaware, the District of Columbia, Maryland, New York, Pe nnsylvania, Virginia, and West Virginia.

As described more fully in Section 2.2.1 below, the Chesapeake Bay TMDL addresses only the restoration of aquatic life uses for the Bay a nd its tidal tributaries and embayments that are impaired from excess nitrogen, phosphorus, and sediment pollution. If Bay segments are impaired for other pollutants, EPA expects that the Bay watershed juri sdictions will develop separate TMDLs to addr ess those pollutants.

Thousands of previously approved TMDLs have b een established to protect local waters across the Chesapeake Bay watershed. While many a ddressed other pollutants, some addressed nitrogen, phosphorus, and/or sediment. For wa tersheds and waterbodies where both local TMDLs and Chesapeake Bay TMDLs have already b een developed or established for nitrogen, phosphorus, and sediment, the more stringent of the TMDLs will apply. In some cases, the reductions required to meet local conditions shown in existing TMDLs may be more stringent than those needed to meet Bay requirements, and vice versa.

2

‐ 6 December 29, 2010Chesapeake Bay TMDL

2

‐ 7 December 29, 2010 

### 2.2.1 Pollutants of Concern The pollutants of concern for this TMDL are nutrients—nitrogen and phosphorus—and sediment. Excessive nitrogen and phosphorus in th e Chesapeake Bay and its tidal tributaries promote a number of undesirable water quality conditions such as exce ssive algal growth, low DO, and reduced water clarity (Smith et al. 1992 ; Kemp et al. 2005). The effect of nitrogen and phosphorus loads on water quality and living reso urces can vary considerably by season and region.

Sediment suspended in the water column reduces the amount of light available to support healthy and extensive SAV or underwater Bay grass co mmunities (Dennison et al. 1993; Kemp et al. 2004). The relative contribution of suspended sediment and algae that causes poor light conditions varies with location in the Bay tidal waters (Gallegos 2001).

Sediment also can contain other pollutant s. For example, certain bacteria (e.g., Escherichia coli ) often cling to sediment. By reducing sediment , reductions in phosphorus delivered to the Bay (and possibly other po llutants such as E. coli ) also will occur. However, EPA is not providing allocations for E. coli or other additional pol lutants in this TMDL.

If Bay segments are impaired for other pollutants, EPA expects that the Bay watershed jurisdictions will develop separate TMDLs to address those pollutants. Because of the actions taken to achieve the Chesapeake Bay TMDL, direct benefits to local water quality conditions in surface waters throughout the Chesapeak e Bay watershed also will occur.



### 2.2.2 Chesapeake Bay Progr am Segmentation Scheme For 27 years, the CBP partners have used variou s versions of a basic segmentation scheme to organize the collection, analysis, and presenta tion of environmental data relating to the Chesapeake Bay. The Chesapeake Bay Program Segmentation Scheme: Revisions, Decisions and Rationales provides documentation of the spatial segmentation scheme of the Chesapeake Bay and its tidal tributaries and the later revisi ons and changes over almost thirty years (USEPA 1983b, 2004b, 2005, 2008a).

Segmentation is the compartmenta lization of the estuary into s ubunits on the basis of selection criteria (USEPA 2008a). Generally, segments reflect certain unique physical, chemical or biological characteristics of a portion of a waterbody (e.g., salinity, influence of pollutant sources, etc.). The 92-segment scheme used in the Chesapeake Bay was derived from the 2004 published 78-segment scheme with additional ju risdictional boundary lines imposed to create 89 segments (USEPA 2004b, 2008a). The sche me includes only the split segments 1 agreed to by the CBP partnership for the tidal James and Potomac rivers for a total of 92 segments (Figure 2-5) ( Table 2-1 ) (USEPA 2008a). The 92 individual wate rsheds that drain directly into one of the 92 Chesapeake Bay segments are re ferred to in this docum ent as Bay segment watersheds (Figure 2-6).

1 A split segment refers to when an established tidal Ba y segment was fully bisected for purposes of applying different water quality criteri a specific to two different portions of the same segment—in the case of the James River, or different assessments of attainment of the same applicable criteria separately from the main river segment—in the case of the Potomac River.Chesapeake Bay TMDL

Source: USEPA 2008a

Figure 2-5. The 92 Chesapeake Bay segments.

2

‐ 8 December 29, 2010Chesapeake Bay TMDL

Source: USEPA 2008a

Figure 2-6. The 92 Chesapeake Bay segment watersheds.

2

‐ 9 December 29, 2010Chesapeake Bay TMDL

Table 2-1 lists the eight major ri ver basins draining to the Ches apeake Bay and their associated Bay segments with information related to each Bay segment’s 2008 section 303(d) list status and whether the Bay segment is addressed by a c onsent decree or MOU. The 303(d) Integrated Report listing categories are as follows:

 Category 1—attaining all WQS

 Category 2—attaining some WQS

 Category 3—insufficient information to determine if WQS are attained

 Category 4—impaired or threatened waters that do not need or already have completed a TMDL

- 4a—TMDL has been completed

- 4b—Other pollution control requ irements are reasonably expe cted to result in the attainment of the WQS in the near future

- 4c—Impairment is not caused by a pollutant

 Category 5—impaired or threaten ed water that requires a TMDL

Most Bay segments are listed as category 5 (impaired for most/a ll designated uses); exceptions are noted in Table 2-1

.

Table 2-1. The Chesapeake Bay 303(d) tidal segments with consent decree (CD)/ memorandum of understanding (MOU) and 303(d) listing status by major river basin and jurisdiction Major river basin Jurisdiction Chesapeake Bay 303(d) segment Segment ID CD/MOU 2008 list status a

MD Big Annemessex River BIGMH

-- 5
MD Bohemia River BOHOH MD MOU 4a for TN and TP
DE C&D Canal, DE C&DOH_DE -- 5
MD C&D Canal, MD C&DOH_MD MD MOU 5
MD Eastern Bay EASMH MD MOU 5
VA Eastern Lower Chesapeake Bay CB7PH VA CD 5

MD Elk River ELKOH MD MOU 5
MD Fishing Bay FSBMH MD MOU 4a for TN and TP
MD Honga River HNGMH MD MOU 5
MD Little Choptank River LCHMH MD MOU 5
MD Lower Chester River CHSMH MD MOU 5
MD Lower Choptank River CHOMH2 MD MOU 5
MD Lower Nanticoke River NANMH

-- 5
MD Lower Pocomoke River, MD POCMH_MD MD MOU 5

VA Lower Pocomoke River, VA POCMH_VA VA CD 5

MD Manokin River MANMH MD MOU 4a for TN and TP Eastern Shore

MD Middle Chester River CHSOH MD MOU 4a for TN and TP

2

‐ 10 December 29, 2010Chesapeake Bay TMDL

2

‐ 11 December 29, 2010 Major river basin Jurisdiction Chesapeake Bay 303(d) segment Segment ID CD/MOU 2008 list status a

MD Middle Choptank River CHOOH MD MOU 5
MD Middle Nanticoke River NANOH MD MOU 5
MD Middle Pocomoke River, MD POCOH_MD MD MOU 5

VA Middle Pocomoke River, VA POCOH_VA

-- 5

MD Mouth of Choptank River CHOMH1 MD MOU 5

MD Northeast River NORTF MD MOU 4a for TN and TP
MD Sassafras River SASO H MD MOU 4a for TP
MD Tangier Sound, MD TANMH_MD MD MOU 5
VA Tangier Sound, VA TANMH_VA

-- 5
MD Upper Chester River CHSTF MD MOU 4a for TN and TP
MD Upper Choptank River CHOTF MD MOU 5
DE Upper Nanticoke River, DE NANTF_DE DE CD finished 5

MD Upper Nanticoke River, MD NANTF_MD MD MOU 5

MD Upper Pocomoke River POCTF MD MOU 5
MD Wicomico River WICMH MD MOU 5
VA Appomattox River APPTF

-- 5
VA Chickahominy River CHKOH

-- 5
VA Eastern Branch Elizabeth River EBEMH VA CD 5

VA Lafayette River LAFMH

-- 5
VA Lower James River JMSMH VA CD 5
VA Lynnhaven River LYNPH VA CD 5
VA Middle James River JMSOH VA CD 5
VA Mouth of Chesapeake Bay CB8PH

-- 5

VA Mouth of James River JMSPH VA CD 5
VA Mouth to mid-Elizabeth River ELIPH VA CD 5

VA Southern Branch Elizabeth River SBEMH VA CD 5

VA Upper James River - Lower JMSTF1 VA CD 5

VA Upper James River - Upper JMSTF2 VA CD 5 James

VA Western Branch Elizabeth River WBEMH VA CD 5

MD Lower Patuxent River PAXMH MD MOU 5
MD Middle Patuxent River PAXOH MD MOU 5 Patuxent

MD Upper Patuxent River PAXTF MD MOU 5Chesapeake Bay TMDL

2

‐ 12 December 29, 2010 Major river basin Jurisdiction Chesapeake Bay 303(d) segment Segment ID CD/MOU 2008 list status a

MD Western Branch Patuxent River WBRTF MD MOU BOD TMDL completed for DO impairments; 4a for BOD
DC Anacostia River, DC ANATF_DC DC CD 3 for DO; 4a for BOD, TN, TP and TSS
MD Anacostia River, MD ANATF_MD MD MOU 4a for BOD, TN, TP and TSS
VA Lower Central Chesapeake Bay, VA b CB5MH_VA b VA CD 5

MD Lower Potomac River, MD POTMH_MD MD MOU 5

VA Lower Potomac River, VA POTMH_VA VA CD 5

MD Mattawoman Creek MATTF MD MOU 5
MD Middle Potomac River, MD - Mainstem POTOH1_MD MD MOU 5

MD Middle Potomac River, MD - Nanjemoy Creek POTOH2_MD MD MOU 5

MD Middle Potomac River, MD - Port Tobacco River POTOH2_MD MD MOU 4a for TN and TP

VA Middle Potomac River, VA POTOH_VA

-- 3 for DO in Migratory Spawning and Nursery (MSN); 2 for SAV and DO in open water
MD Piscataway Creek PISTF MD MOU 5
DC Upper Potomac River, DC POTTF_DC DC CD 3 for DO, 5 for pH

MD Upper Potomac River, MD POTTF_MD MD MOU 5 Potomac

VA Upper Potomac River, VA POTTF_VA

-- 3 for DO in Migratory Spawning and Nursery; 2 for SAV and DO in open water
VA Corrotoman River CRRMH

-- 5 Rappa- hannock VA Lower Rappahannock River RPPMH VA CD 5Chesapeake Bay TMDL

2

‐ 13 December 29, 2010 Major river basin Jurisdiction Chesapeake Bay 303(d) segment Segment ID CD/MOU 2008 list status a

VA Middle Rappahannock River RPPOH

-- 3 for DO in Migratory Spawning and Nursery; 2 for SAV and DO in open water
VA Upper Rappahannock River RPPTF

-- 5

VA Western Lower Chesapeake Bay b CB6PH b VA CD 5

Susquehanna MD Northern Chesapeake Bay b CB1TF b MD MOU 5

MD Back River BACOH MD MOU 4a for TN and TP
MD Bush River BSHOH MD MOU 5
MD Gunpowder River GUNOH MD MOU 5
MD Lower Central Chesapeake Bay, MD b CB5MH_MD b MD MOU 5

MD Magothy River MAGMH MD MOU 5
MD Middle Central Chesapeake Bay b CB4MH b MD MOU 5

MD Middle River MIDOH MD MOU 5
MD Patapsco River PATMH MD MOU 5
MD Rhode River RHDMH MD MOU 5
MD Severn River SEVMH MD MOU 5
MD South River SOUMH MD MOU 5
MD Upper Central Chesapeake Bay b CB3MH b MD MOU 5

MD Upper Chesapeake Bay b CB2OH b MD MOU 5 Western Shore

MD West River WSTMH MD MOU 5
VA Lower Mattaponi River MPNOH VA CD 5
VA Lower Pamunkey River PMKOH VA CD 5
VA Lower York River YRKPH VA CD 5
VA Middle York River YRKMH VA CD 5
VA Mobjack Bay MOBPH

-- 5
VA Piankatank River PIAMH

-- 5
VA Upper Mattaponi River MPNTF VA CD 5 York

VA Upper Pamunkey River PMKTF VA CD 5

Sources: American Canoe Association v. EPA; American Littoral Society, et al. v. EPA, et al.; DC DOH 1998; DC DOE 2008; DE DNREC 1996; DE DNREC 2008; Kingman Park Civ ic Association, et al. vs. EPA; MDE 1998, 2004, 2008; USEPA 2008 a; VA DEQ 1998; VA DEQ 2008 a. BOD = biological oxygen demand; DO = dissolved oxygen ; TN = total nitrogen; TP = total phosphorus; TSS = total suspended solids b. More than one river basin flows into this tidal segmentChesapeake Bay TMDL

2

‐ 14 December 29, 2010 

### 2.2.3 Jurisdictions’ 2008 303(d) Listings The Chesapeake Bay TMDL is based on the most recent EPA-approved tidal Bay jurisdictions’ section 303(d) lists, which ar e the 2008 303(d) listings. 2 Those section 303(d) lists identify 89 of the 92 Chesapeake Bay segments as impaired on either Category 4a (impaired, TMDL has been developed) or Category 5 (impaired, needs TMDL ) because of various factors, including low DO levels, insufficient SAV, excess chlorophyll a , biological/nutrient indicators, total nitrogen, total phosphorus, total suspended solids (TSS), biological oxygen dema nd (BOD), and pH (caused by excessive nitrogen and phosphorus fueling al gal blooms) (DC DOE 2008; DE DNREC 2008; MDE 2008; VADEQ 2008).

Three Chesapeake Bay segments are not listed in Category 4a or 5 on Virginia’s 2008 integrated report:

 Upper Potomac River (POTTF_VA)

 Middle Potomac River (POTOH_VA)

 Middle Rappahannock River (RPPOH)

Those three segments are listed as either Category 2 (some uses me t, other uses have insufficient information to determine impairment) or Category 3 (insufficient information to determine if impaired) (VA DEQ 2008). Because their listing st atus raises a reasonable possibility that they are impaired, and because those segments are ti dally interconnected with other impaired Bay segments, it is appropriate that they also be addressed by the Chesapeake Bay TMDL.

The first segment, Virginia’s Upper Potomac Ri ver (POTTF_VA), encompasses a series of small tidal embayments that are tidally interconne cted with Maryland’s Upper Potomac River (POTTF_MD) segment and the District of Co lumbia’s Upper Potomac River (POTTF_DC) segment (USEPA 2008a), both of which are listed as Category 5 of Maryland’s and the District of Columbia’s respective 2008 integrated repor ts (DCDOE 2008; MDE 2008). Loads originating in the watershed that drains directly to Virg inia’s Upper Potomac River segment influence the water quality in the two adjacent Ma ryland and District of Columbia impaired tidal segments and other down-tide segments.

The second segment, Virginia’s Middle Potomac River (POTOH_VA), also encompasses a series of small tidal embayments that are tidally interconnected with Maryland’s Middle Potomac River (POTOH_MD) segment (USEPA 2008a), which is listed as Category 5 on Maryland’s 2008 integrated report (MDE 2008). Loads originating in the watershed that drains directly to Virginia’s Middle Potomac River segm ent influence the water quality in the adjacent Maryland impaired tidal segment and other down-tide impaired segments.

The third segment, Virginia’s Middle Rappaha nnock River (RPPOH), is tidally interconnected with both the Lower Rappahannock River (R PPMH) and the Upper Rappahannock River (RPPTF) segments (USEPA 2008a), both of whic h are listed as Category 5 on Virginia’s 2008 integrated report (VADEQ 2008). Loads originating in the watershed that drains directly to

2 At the time EPA applied the Bay models for development of the allocations starting in 2009, the 2008 section 303(d) lists were the most recent appr oved lists. Although EPA subsequently received 2010 sectio n 303(d) lists for approval from all tidal jurisdictions, EPA used the approved 2008 lists in establishing the Bay TMDL to have a consistent basis for the TMDL.Chesapeake Bay TMDL

2

‐ 15 December 29, 2010 Virginia’s Middle Rappahannock River segment influence the water quality in the adjacent Virginia impaired tidal segmen ts and other down-tide segments.

As detailed in Section 9, TMDLs have been comp leted as part of the Chesapeake Bay TMDL for all 92 Chesapeake Bay segments listed in Table 2-1 (see Section 9). These include TMDLs for the above described three Virginia Bay segments because they flow into impaired tidal Bay segments, and reductions in nitrogen, phosphorus, and sediment loadings from their respective watersheds, therefore, are necessary to achie ve the Bay jurisdictions’ Chesapeake Bay WQS.



### 2.2.4 2008 303(d) Listing Segments Compared to Consent Decree and MOU Segments

To ensure that EPA established TMDLs fo r all necessary Bay segments—all 2008 listed segments, all Virginia, Delaware, and the Distri ct of Columbia TMDL consent decree segments, and all Maryland MOU segments—EPA compared the 2008 listed segments with those included on those consent decrees and MOUs ( Table 2-1 ). In total, 77 segmen ts are addressed by the Virginia and District of Colu mbia consent decrees and the Maryland MOU: 22 segm ents are on the Virginia TMDL consent decree; 2 segments are on the Delaware TMDL consent decree; 2 segments are on the District of Columbia TMDL consent decree; and 51 segments are on the Maryland TMDL MOU ( Table 2-2 ). The evaluation found that al l segments of the Virginia consent decree, Delaware consent de cree, the Dist rict of Columbia consent decree, and Maryland MOU are included in the list of 92 Chesapeake Bay segments fo r which nitrogen, phosphorus, and sediment TMDLs have been established under the Bay TMDL.

Table 2-2. Comparison of consent decree/MOU segments with total number of Bay segments

Jurisdiction Consent decree or MOU segments Chesapeake Bay segments Virginia 22 35
District of Columbia 2 2 Maryland 51 53
Delaware 2 a 2
Total 77 92 Source: Adapted from Table 2-1

. a. Tw o consent decrees affect one Bay segment in Dela ware, but TMDLs have already been established for both waterbodies.Chesapeake Bay TMDL



## SECTION 3. C HESAPEAKE BAY WATER QUALITY STANDARDS

WQS consist of four basic elements: designated uses, water quality criteria, an antidegradation policy (to maintain and protect existing uses and high-quality waters), and general policies (addressing implementation issues such as low fl ows, variances, and mixing zones). Designated uses are a jurisdiction’s goals and expectati ons for each of the individual surface waters (e.g., coldwater fisheries, public water supply, and primary contact re creation). EPA’s WQS regulation defines designated uses as the “uses specified in WQS for each waterbody or segment, whether or not they are being attained” (40 CFR 131.3). Water quality criteria may be numeric or narrative, and represent a quality of water that supports a partic ular use. When water quality criteria are met, water quality is expected to protect its designated use. Numeric water quality criteria are generally chemical-specific and reflec t specific levels of po llutants that, if found in the waterbody, do not impair its designated uses (e .g., physical or chemical characteristics like temperature, minimum concentration of DO, and the maximum concentrations of toxic pollutants).

Starting in 1986, EPA and its CBP partners emba rked on a process to synthesize scientific evidence on the water quality requirements of hundreds of aquatic sp ecies and biological communities inhabiting Chesapeake Bay and its tidal tributaries and embayments. The 1987 Chesapeake Bay Agreement included a commitment to “develop and adopt guidelines for the protection of water quality and habitat conditions necessary to support the living resources found in the Chesapeake Bay system, and to use these guidelines in the implementation of water quality and habitat quality programs” (CEC 1987). Th e CBP partnership initially published two syntheses of the available scientific findings supp orting establishment of habitat requirements for 31 target species (CBP 1987; Funderburk et al. 1991). Those efforts spawned development and publication of synthesis documents focused on DO requirements (Jordan et al. 1992) and underwater Bay grasses habitat requirements (B atiuk et al. 1992, 2000). On the basis of that work, in part, EPA published as guidance the Ch esapeake Bay water quality criteria (USEPA 2003a) and the Chesapeake Bay refined aquatic life designated uses and attainability (USEPA 2003d) documents.

Guided by those efforts, Delaware, the District of Columbia, Maryland, and Virginia adopted jurisdiction-specific Chesapeake Bay WQS regul ations in 2004–2005 consistent with the EPA published guidance. EPA then reviewed and a pproved the four tidal Bay jurisdictions’ WQS submissions pursuant to CWA section 303(c).

Since 2005, Delaware, Maryland, Virginia, and the Di strict of Columbia each has proposed and adopted very specific amendments to its resp ective Chesapeake Bay WQS regulations. Each jurisdiction’s process for amending its existing Chesapeake Bay WQS regulations requires full public notice, public review and comment, and re sponse to public comments before submission to EPA Region 3 for final EPA review and approval.

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### 3.1 CHESAPEAKE BAY WATE R QUALITY CRITERIA AND DESIGNATED USES The above described DO, underwater Bay grasse s, and Bay habitat requirements documents (Batiuk et al. 1992, 2000; CBP 1987; Funderburk et al. 1991; Jordan et al. 1991), supplemented by additional scientific research findings, provided the basis for developing the applicable water quality criteria guidance for the Chesapeake Bay. The criteria assessment guidance is documented within EPA’s Bay criteria (USEPA 2003a), designated uses/attainability (USEPA 2003d), and Bay segmentation (USEPA 2004b) docum ents and the subsequent seven addenda (USEPA 2004a, 2004e, 2005, 2007a, 2007b, 2008a, 2010a ). EPA Region 3 published those documents as guidance in accordance with CWA sect ions 117(b) and 303 to derive water quality criteria specifically for addre ssing the critical nutr ient and sediment enrichment parameters necessary to protect designated a quatic life uses in the Bay ( Table 3-1 ). These criteria serve as surrogate numeric criteria for n itrogen, phosphorus, and sedim ent.

Table 3-1. Chesapeake Bay water quality criteria and designated use related documentation and addenda

Document title Month/year published Document content and description Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries. EPA 903-R-03- 002. [USEPA 2003a] April 2003 Original Chesapeake Bay water quality criteria document.

Technical Support Document for Identification of Chesapeake Bay Designated Uses and Attainability. EPA 903-R-03-004. [USEPA 2003d] October 2003 Original Chesapeake Bay tidal waters designated uses document.

Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries—2004 Addendum. EPA 903-R-03-002. [USEPA 2004a] October 2004 Addresses endangered species protection, assessment of DO criteria, derivation of site-specific DO criteria, pycnocline boundary delineation methodology, and updated water clarity criteria/SAV restoration acreage assessment procedures. Technical Support Document for Identification of Chesapeake Bay Designated Uses and Attainability—2004 Addendum. EPA 903-R-04-006. [USEPA 2004e] October 2004 Addresses refinements to Bay tidal waters designated use boundaries, segmentation boundaries, and Potomac River jurisdictional boundaries; documents SAV no-grow zones, restoration goal, and shallow-water acreages. Chesapeake Bay Program Analytical Segmentation Scheme: Revisions, Decisions and Rationales 1983–2003. EPA 903-R-04-008. C BP/TRS 268-04. [USEPA 2004b] October 2004 Details documentation on the history of the segmentation schemes and provides coordinates, georefer ences, and narrative descriptions of the 2003 segmentation scheme.

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3

‐ 3 December 29, 2010 Document title Month/year published Document content and description Chesapeake Bay Program Analytical Segmentation Scheme: Revisions, Decisions and Rationales 1983–2003: 2005 Addendum. EPA 903-R-05-004. CBP/TRS 278-06. [USEPA 2005] December 2005 Addresses methods used to subdivide the segments by jurisdiction and provides coordinates, georefer ences, and narrative descriptions for those subdivided segments. Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries—2007 Addendum. EPA 903-R-07-003. CBP/TRS 285-07. [USEPA 2007a] July 2007 Addresses refinements to the Bay water quality DO, water clarity/SAV, and chlorophyll a criteria assessment methodologies and documents the framework for Bay tidal waters 303(d) list decision making. Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries—2007 Chlorophyll Criteria Addendum. EPA 903- R-07-005. CBP/TRS 288/07. [USEPA 2007b] November 2007 Publishes a set of numerical chlorophyll a criteria for Chesapeake Bay and the supporting criteria assessment procedures.

Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries—2008 Technical Support for Criteria Assessment Protocols Addendum. EPA 903-R-08-001. CBP/TRS 290-08. [USEPA 2008a] September 2008 Addresses refinements to the Bay water quality DO, water clarity/SAV and chlorophyll a criteria assessment methodologies and documents the 2008 92-segment scheme for Bay tidal waters.

Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries—2010 Technical Support for Criteria Assessment Protocols Addendum. EPA 903-R-10-002. CBP/TRS 301-10. [USEPA 2010a] May 2010 Addresses refinements to procedures for defining designated uses, procedures for deriving biologically based reference curves for DO criteria assessment and chlorophyll a criteria assessment procedures.

Before adoption into each Bay jurisdiction’s WQ S regulations, each set of criteria, criteria assessment procedures, designated uses, and propos ed WQS were subject to extensive scientific, programmatic, and public review.

The original 2003 water quality cr iteria, assessment procedures, and designated uses all went through independent scientific peer reviews sponsored by the CBP’s STAC and public review. The CBP’s Water Quality Steeri ng Committee’s water quality crite ria and designated use teams then reviewed and approved them. Finally, the CBP’s Water Quality Steering Committee reviewed and approved them for EPA pub lication on behalf of the partnership.

Since the publication of the original Chesap eake Bay water quality cr iteria document (USEPA 2003a), Chesapeake Bay designated uses and attainability document (USEPA 2003d), and Chesapeake Bay segmentation document (USEPA 2004b), EPA has published enhancements to the criteria assessment proce dures, designated use boundaries, and Bay segmentation scheme. Specifically, EPA has published five a ddenda—USEPA 2004a, 2007a, 2007b, 2008a, 2010a—to the original 2003 Bay criteria document (U SEPA 2003a), one addendum—USEPA 2004e—toChesapeake Bay TMDL

the original 2003 Bay designated use/attain ability document (USE PA 2003d), and one addendum—USEPA 2005—to the original Bay se gmentation document (USEPA 2004b) (see Table 3-1 ).

Those revisions have undergone independent scientific peer reviews, sponsored by the CBP’s STAC, before review and approval by the CBP ’s Criteria Assessment Protocols W orkgroup and then the Water Quality Steering Committee/Wa ter Quality Implementation Team for EPA publication on behalf of the partnership. Examples include the cumulative frequency distribution approach (STAC 2006) and the biologi cal reference curves (STAC 2009).



### 3.1.1 Tidal Water Designated Uses EPA and its seven watershed jurisdiction partners agreed on five refined aquatic life designated uses reflecting the habitats of an array of recreationally, commercially, and ecologically important species and biological communities (USEPA 2003d, 2004e, 2010a). The five tidal Bay designated uses are applied, where appropriate, co nsistently across Delaware, the District of Columbia, Maryland, and Virginia’s portions of th e Chesapeake Bay and its tidal tributary and embayment waters. The vertical and horizonta l breadth and temporal application of the designated use boundaries are based on a combinati on of natural factors, historical records, physical features, hydrology, bathymetry, and ot her scientific consid erations (USEPA 2003d, 2004e, 2010a). Table 3-2 outlines the Chesapeake Bay tidal water designated uses, which are illustr ated in Figure 3-1

.

Table 3-2. Five Chesapeake Bay tidal waters designated uses

Tidal water designated use Chesapeake Bay habitats and communities protected Migratory fish spawning and nursery Migratory and resident tidal freshwater finfish during the latewinter/spring spawning and nursery season in tidal freshwater to lowsalinity habitats. Shallow-water Bay grass Underwater Bay grasse s and fish and crab species that depend on the shallow-water habitat provided by underwater Bay grass beds. Open-water fish and shellfish Diverse populations of sport fish, including striped bass, bluefish, mackerel and sea trout, as well as important bait fish such as menhaden and silversides in surface water habitats within tidal creeks, rivers, embayments, and the mainstem Chesapeake Bay year-round. Deep-water seasonal fish and shellfish Animals inhabiting the deeper transitional water column and bottom habitats between the well-mixed surface waters and the very deep channels during the summer months (e.g., bottom-feeding fish, crabs and oysters, as well as other impo rtant species, including the Bay anchovy). Deep-channel seasonal refuge Bottom-sediment-dwelling worms and small clams that serve as food for bottom-feeding fish and crabs in the very deep channels in summer.
Sources: USEPA 2003d, 2004e

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Source: USEPA 2003d

Figure 3

- 1 . Conceptual illustration of the five Chesapeake Bay tidal water designated use zones.

Table 3-3 lists the designated uses for each of the 92 Chesapeake Bay segments pursuant to Delaware, the District of Columbia, Maryla nd, and Virginia’s existing WQS regulations. Am ended based on USEPA 2010a, Table 3-3 was orig inally published as Table V-1 on pages 51–53 of the Ambient Water Quality Criteria for Di ssolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries 2007 Addendum (USEPA 2007a)

, which is an updated version of Table IV-3 originally published on pages 62–63 of the 2003 Technical Support Document for Identificati on of Chesapeake Bay Designated Uses and Attainability (USEPA 2003d)

. The absence of an X in the sh allow-water Bay grass designated use column indicates that the Bay segment has b een entirely delineated as an SAV no-grow zone and, therefore, the shallow-water Bay grass desi gnated use does not apply to that Bay segment (USEPA 2004e).

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Table 3-3. Current tidal water designated uses by Chesapeake Bay segment

Migratory fish spawning & nursery Open water fish & shellfish Deep water seasonal

fish & shellfish Deep channel seasonal

refuge Shallow water Bay

grasses

CB segment name CB segment Juris. Feb. 1– May 31 Year-round June 1– Sept. 30 June 1– Sept. 30 SAV growing

season Northern Chesapeake Bay CB1TF MD X X X Upper Chesapeake Bay CB2OH MD X X X Upper Central Chesapeake Bay CB3MH MD X X X X X

Middle Central Chesapeake Bay CB4MH MD X X X X X

Lower Central Chesapeake Bay , MD CB5MH_MD MD X X X X

Lower Central Chesapeake Bay, VA CB5MH_VA VA X X X X

Western Lower Chesapeake Bay CB6PH VA X X X

Eastern Lower Chesapeake Bay CB7PH VA X X X

Mouth of the Chesapeake Bay CB8PH VA X X

Bush River BSHOH MD X X X Gunpowder River GUNOH MD X X X

Middle River MIDOH MD X X X

Back River BACOH MD X X X Patapsco River PATMH MD X X X X Magothy River MAGMH MD X X X X
Severn River SEVMH MD X X X X
South River SOUMH MD X X X X

Rhode River RHDMH MD X X X

West River WSTMH MD X X X Upper Patuxent River PAXTF MD X X X

Western Branch Patuxent River WBRTF MD X X X

Middle Patuxent River PAXOH MD X X X

Lower Patuxent River PAXMH MD X X X X Upper Potomac River, DC POTTF_DC DC X X X Upper Potomac River, MD POTTF_MD MD X X X Upper Potomac River, VA POTTF_VA VA X X X Anacostia River, DC ANATF_DC DC X X X
Anacostia River, MD ANATF_MD MD X X X Piscataway Creek PISTF MD X X X
Mattawoman Creek MATTF MD X X X

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‐ 7 December 29, 2010 Migratory fish spawning & nursery Open water fish & shellfish Deep water seasonal

fish & shellfish Deep channel seasonal

refuge Shallow water Bay

grasses

CB segment name CB segment Juris. Feb. 1– May 31 Year-round June 1– Sept. 30 June 1– Sept. 30 SAV growing

season Middle Potomac River, MD-Mainstem POTOH1_MD MD X X X

Middle Potomac River, MD-Nanjemoy Creek POTOH2_MD MD X X X

Middle Potomac River, MD-Port Tobacco River POTOH3_MD MD X X X

Middle Potomac River, VA POTOH_VA VA X X X
Lower Potomac River, MD POTMH_MD MD X X X X X
Lower Potomac River, VA POTMH_VA VA X X X X X Upper Rappahannock River RPPTF VA X X X

Middle Rappahannock River RPPOH VA X X X

Lower Rappahannock River RPPMH VA X X X X X

Corrotoman River CRRMH VA X X X

Piankatank River PIAMH VA X X Upper Mattaponi River MPNTF VA X X X Lower Mattaponi River MPNOH VA X X Upper Pamunkey River PMKTF VA X X X Lower Pamunkey River PMKOH VA X X

Middle York River YRKMH VA X X X

Lower York River YRKPH VA X X X Mobjack Bay MOBPH VA X X Upper James River-Lower JMSTF1 VA X X X Upper James River-Upper JMSTF2 VA X X X Appomattox River APPTF VA X X X

Middle James River JMSOH VA X X X Chickahominy River CHKOH VA X X X

Lower James River JMSMH VA X X X

Mouth of the James River JMSPH VA X X

Western Branch Elizabeth River WBEMH VA X

Southern Branch Elizabeth River SBEMH VA X

Eastern Branch Elizabeth River EBEMH VA X

Lafayette River LAFMH VA X
Mouth of the Elizabeth River ELIPH VA X X XChesapeake Bay TMDL

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‐ 8 December 29, 2010 Migratory fish spawning & nursery Open water fish & shellfish Deep water seasonal

fish & shellfish Deep channel seasonal

refuge Shallow water Bay

grasses

CB segment name CB segment Juris. Feb. 1– May 31 Year-round June 1– Sept. 30 June 1– Sept. 30 SAV growing

season Lynnhaven River LYNPH VA X X

Northeast River NORTF MD X X X C&D Canal, DE C&DOH_DE DE X X X C&D Canal, MD C&DOH_MD MD X X X

Bohemia River BOHOH MD X X X

Elk River ELKOH MD X X X
Sassafras River SASOH MD X X X Upper Chester River CHSTF MD X X X
Middle Chester River CHSOH MD X X X

Lower Chester River CHSMH MD X X X X X Eastern Bay EASMH MD X X X X Upper Choptank River CHOTF MD X X Middle Choptank River CHOOH MD X X X Lower Choptank River CHOMH2 MD X X X Mouth of the Choptank River CHOMH1 MD X X X

Little Choptank River LCHMH MD X X Honga River HNGMH MD X X Fishing Bay FSBMH MD X X X Upper Nanticoke River, MD NANTF_MD MD X X

Upper Nanticoke River, DE NANTF_DE DE X X X

Middle Nanticoke River NANOH MD X X X

Lower Nanticoke River NANMH MD X X X

Wicomico River WICMH MD X X X

Manokin River MANMH MD X X X Big Annemessex River BIGMH MD X X X Upper Pocomoke River POCTF MD X X
Middle Pocomoke River, MD POCOH_MD MD X X

Middle Pocomoke River, VA POCOH_VA VA X X

Lower Pocomoke River, MD POCMH_MD MD X X X

Lower Pocomoke River, VA POCMH_VA VA X X X

Tangier Sound, MD TANMH_MD MD X X Tangier Sound, VA TANMH_VA VA X X Sources: USEPA 2003d, 2004e, 2007a, 2010aChesapeake Bay TMDL



### 3.1.2 Dissolved Oxygen Criteria Oxygen is one of the most essential environmental constituents s upporting life. In the Chesapeake Bay’s deeper waters, there is a na tural tendency toward reduced DO conditions because of the Bay’s physical morphology and estuarine circulation. The Chesapeake Bay’s highly productive shallow waters , coupled with strong density stratification (preventing reaeration); long residence times (weeks to months ); low tidal energy; an d tendency to retain, recycle, and regenerate nutrients from the su rrounding watershed all set the stage for low DO conditions.

Against that backdrop, EPA worked closely with its seven watershed partners and the larger Bay scientific community to derive and publish a set of DO criteria to protect specific aquatic life communities and reflect the Chesapeake Bay’s natural processes that define distinct habitats ( Figure 3-2 ) (USEPA 2003a; Batiuk et al. 2009). Work ing with the National Marine Fisheries Service, EPA also ensured that the DO criteri a were protective of th e shortnose sturgeon, a species listed as endanger ed by the Endangered Species Act (NMFS 2003; USEPA 2003b).

Source: USEPA 2003a

Figure 3-2. Dissolved oxygen concentrations (mg/L) required by different Chesapeake Bay species and biological communities.

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Criteria for the migratory fish spawning and nur sery, shallow-water Bay grass and open-water fish and shellfish designated uses were set at levels to prevent impairment of growth and to protect the reproduction and survival of all orga nisms living in the open-water column habitats ( Table 3-4 ) (USEPA 2003a). Criteria fo r deep-water seasonal fish and shellfish designated use habitats, during seasons when the water colum n is significantly stratified, were set at levels to protect juvenile and adult fish, shellfish, and the recr uitment success of the Bay anchovy. Criteria for deep-channel seasonal refuge designated use habitats in summer were set to protect the survival of bottom sediment-dwelling worms and clams.

Table 3-4. Current Chesapeake Bay DO criteria

Designated

use Criteria concentration/duration Protection provided Temporal application 7-day mean ≥ 6 mg/L (tidal habitats with 0–0.5 ppt salinity) Survival and growth of larval/juvenile tidal-fresh resident fish; protective of threatened/endangered species Instantaneous minimum
≥ 5 mg/L Survival and growth of larval/juvenile migratory fish; protective of threatened/endangered species February 1–May 31 Migratory fish spawning and nursery use

Open-water fish and shellfish designated use criteria apply June 1–January 31 Shallow-water Bay grass use Open-water fish and shellfish designated use criteria apply Year-round

30-day mean ≥ 5.5 mg/L (tidal habitats with 0–0.5 ppt salinity) Growth of tidal-fresh juvenile and adult fish; protective of threatened/endangered species 30-day mean ≥ 5 mg/L (tidal habitats with >0.5 ppt salinity) Growth of larval, juvenile, and adult fish and shellfish; protective of threatened/endangered species 7-day mean ≥ 4 mg/L Survival of open-water fish larvae Open-water fish and shellfish use

Instantaneous minimum
≥ 3.2 mg/L Survival of threatened/endangered sturgeon species a Year-round

30-day mean ≥ 3 mg/L Survival and recruitment of Bay anchovy eggs and larvae 1-day mean ≥ 2.3 mg/L Survival of open-water juvenile and adult fish Instantaneous minimum
≥ 1.7 mg/L Survival of Bay anchovy eggs and larvae June 1–September 30 Deep-water seasonal fish and shellfish

use

Open-water fish and shellfish designated use criteria apply October 1–May 31 Instantaneous minimum
≥ 1 mg/L Survival of bottom-dwelling worms and clams June 1–September 30 Deep-channel seasonal refuge use Open-water fish and shellfish designated use criteria apply October 1–May 31
Source: USEPA 2003a Notes: mg/L = milligrams per liter; ppt = parts per thousand salinity a. At temperatures considered stre ssful to shortnose sturgeon (> 29 degrees Celsius), DO concentrations above an instantaneous minimum of 4.3 mg/L will protec t survival of this listed sturgeon species.

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### 3.1.3 Chlorophyll a Criteria EPA’s 2003 Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Ti dal Tributaries (USEPA 2003a) describes the applicable narrative crit eria for chlorophyll a:

“Concentrations of chlorophyll a in free-floating microscopic a quatic plants (algae) shall not exceed levels that result in ecologically unde sirable consequences—such as reduced water clarity, low dissolved oxygen, food supply imba lances, proliferation of species deemed potentially harmful to aquatic life or humans or aesthetic ally objectionable conditions—or otherwise render tidal waters unsu itable for designated uses.”

In 2007 EPA published numeric chlorophyll a criteria guidance pr otective of open-water designated use impairment by harmful algal bl ooms and provided recommended reference chlorophyll a concentrations for historic chlorophyll a levels, and DO and water clarity impairments (USEPA 2007b).

Delaware, the District of Columbia, Maryla nd, and Virginia all a dopted EPA’s narrative chlorophyll a criteria. Additionally, the District of Columbia and Virginia adopted numeric chlorophyll a criteria for certain tidal waters as de tailed in Sections 3.2.2 and 3.2.7, respectively.



### 3.1.4 Water Clarity/Underwat er Bay Grasses Criteria Underwater bay grass beds create rich animal hab itats that support the grow th of diverse fish and invertebrate populations. Underw ater bay grasses, also refe rred to as submerged aquatic vegetation (SAV), help improve tidal water quality by retaining nitrogen and phosphorus as plant material, stabilizing bottom sediment (preventin g their resuspension) and reducing shoreline erosion. The health and survival of such underw ater plant communities in the Chesapeake Bay and its tidal tributaries and embayments depe nd on suitable environmental conditions (Dennison et al. 1993; Kemp et al. 2004).

The loss of SAV from the shallow waters of the Chesapeake Bay, which was first noted in the early 1960s, is a widespread, well-documented problem (Orth and Moore 1983; Orth et al. 2010b). The primary causes of the decline of SAV are nutrient over-enrichment, increased suspended sediment in the water, and associated reductions in light ava ilability (Kemp et al. 2004). To restore the critical ha bitats and food sources, enough li ght must penetrate the shallow waters to support the survival, growth, and repr opagation of diverse, healthy, SAV communities (Dennison et al. 1993).

EPA, working closely with its se ven watershed partners and the la rger Bay scientific community, derived and published Chesapeake Bay water clarity criteria to establish the minimum level of light penetration required to support the surviv al, growth, and conti nued propagation of SAV (USEPA 2003a). Chesapeake Bay-specific water clar ity criteria were derived for low and higher salinity habitats using a worldwid e literature synthesis, an evalua tion of Chesapeake Bay-specific field study findings, and application mode l simulations and diagnostic tools ( Table 3-5 ).

The water clarity criteria, applied only during the SAV growing seasons, are presented in term s of the percent ambient light at th e water surface extending thro ugh the water column and the

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equivalent Secchi depth by application depth ( Table 3-5 ). The recommended pe rcent light-throughwater criteri a can be directly meas ured using a Secchi disk or a light meter. A specif ic application depth is required to apply and determine attainment of the water clarity criteria ( Table 3-6 ).

SAV restoration acreage goals and water clarity application depths we re developed based on historic and recen t data on the distribution of SAV (USEPA 2003d). Detailed analyses using that data—including historical aeri al photographs—were undertaken to map the distribution and depth of historical SAV beds in the Chesapeak e Bay and its tidal tributaries and embayments. The analyses led to the adoption of the single be st year method that considers historical SAV distributions from the 1930s through the early 19 70s and more recent distributions since 1978 to the present mapped through annual SAV aerial surv eys of the Bay’s shallow-water habitats. Using that method, the EPA and its watershed part ners established a Bay- wide SAV restoration goal of 185,000 acres and Bay segm ent-specific acreage goals ( Table 3-6 ) (USEPA 2003d).

Table 3-5. Summary of Chesapeake Bay water clarity criteria for application to shallowwater Bay grass designated use habitats Water clarity criteria as Secchi depth a Water clarity criteria application depths (meters)

0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 Salinity regime b Water clarity criteria(percent lightthroughwater) Secchi depth for above criteria application depth (meters) Temporal application

Tidal-fresh 13% 0.2 0.4 0.5 0.7 0.9 1.1 1.2 1.4 April 1–Oct 31 Oligohaline 13% 0.2 0.4 0.5 0.7 0.9 1.1 1.2 1.4 April 1–Oct 31
Mesohaline 22% 0.2 0.5 0.7 1.0 1.2 1.4 1.7 1.9 April 1–Oct 31 Polyhaline 22% 0.2 0.5 0.7 1.0 1.2 1.4 1.7 1.9 March 1–May 31 Sept 1–Nov 30

Source: USEPA 2003a a. Based on application of the Equation IV-1 published in USEPA 2003a, PLW = 100exp(-K d Z), where the appropriate percent light through water (PLW) criterion value and the se lected application depth (see Table 3-6) are inserted and the equation is solved for K d . The generated K d value is then converted to Secchi depth (in meters) using the conversion factor K d = 1.45/Secchi depth. b. Tidal fresh = 0-0.5 ppt salinity; oligohaline = >0.5-5 ppt salinity; mesohaline = >5-18 ppt salinity; polyhaline = >18 ppt salinity

Table 3-6. Chesapeake Bay SAV restoration acreage goals and application depths

Segment description State Segment designator SAV acreage restoration goal (acres) Application depth (meters) Northern Chesapeake Bay MD CB1TF2 12,149 2.0 Northern Chesapeake Bay MD CB1TF1 754 1.0 Upper Chesapeake Bay MD CB2OH 705 0.5 Upper Central Chesapeake Bay MD CB3MH 1,370 0.5 Middle Central Chesapeake Bay MD CB4MH 2,533 2.0 Lower Central Chesapeake Bay MD CB5MH_MD 8,270 2.0 Lower Central Chesapeake Bay VA CB5MH_VA 7,633 2.0 Western Lower Chesapeake Bay VA CB6PH 1,267 1.0

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‐ 13 December 29, 2010 Segment description State Segment designator SAV acreage restoration goal (acres) Application depth (meters) Eastern Lower Chesapeake Bay VA CB7PH 15,107 2.0 Mouth of Chesapeake Bay VA CB8PH 11 0.5
Bush River MD BSHOH 350 0.5 Gunpowder River-Upper MD GUNOH2 572 2.0 Gunpowder River-Lower MD GUNOH1 1,860 0.5
Middle River MD MIDOH 879 2.0
Back River MD BACOH 30 0.5 Patapsco River MD PATMH 389 1.0 Magothy MD MAGMH 579 1.0 Severn River MD SEVMH 455 1.0 South River MD SOUMH 479 1.0
Rhode River MD RHDMH 60 0.5
West River MD WSTMH 238 0.5 Upper Patuxent River MD PAXTF 205 0.5
Middle Patuxent River MD PAXOH 115 0.5
Lower Patuxent River MD PAXMH1 1,459 2.0
Lower Patuxent River MD PAXMH2 172 0.5
Lower Patuxent River MD PAXMH4 1 0.5
Lower Patuxent River MD PAXMH5 2 0.5 Upper Potomac River MD POTTF_MD 2,142 2.0 Piscataway Creek MD PISTF 789 2.0 Mattawoman Creek MD MATTF 792 1.0
Middle Potomac River MD POTOH1 1,387 2.0
Middle Potomac River MD POTOH2 262 1.0
Middle Potomac River MD POTOH3 1,153 1.0
Lower Potomac River MD POTMH_MD 7,088 1.0 Upper Potomac River VA POTTF_VA 2,093 2.0
Middle Potomac River VA POTOH_VA 1,503 2.0
Lower Potomac River VA POTMH_VA 4,250 1.0 Upper Rappahannock River VA RPPTF 66 0.5 Middle Rappahannock River VA RPPOH 4 0.5 Lower Rappahannock River VA RPPMH 1,700 1.0 Corrotoman River VA CRRMH 768 1.0
Piankatank River VA PIAMH 3,479 2.0 Upper Mattaponi River VA MPNTF 85 0.5 Upper Pamunkey River VA PMKTF 187 0.5
Middle York River VA YRKMH 239 0.5
Lower York River VA YRKPH 2,793 1.0 Mobjack Bay VA MOBPH 15,901 2.0 Upper James River-Upper VA JMSTF2 200 0.5 Upper James River-Lower VA JMSTF1 1,000 0.5 Appomattox River VA APPTF 379 0.5
Middle James River VA JMSOH 15 0.5Chesapeake Bay TMDL

3

‐ 14 December 29, 2010 Segment description State Segment designator SAV acreage restoration goal (acres) Application depth (meters) Chickahominy River VA CHKOH 535 0.5
Lower James River VA JMSMH 200 0.5 Mouth of the James River VA JMSPH 300 1.0 Lynnhaven River VA LYNPH 107 0.5
Northeast River MD NORTF 89 0.5 Chesapeake & Delaware Canal MD C&DOH_MD 7 0.5
Bohemia River MD BOHOH 354 0.5
Elk River MD ELKOH1 1,844 2.0
Elk River MD ELKOH2 190 0.5 Sassafras River MD SASOH1 1,073 2.0 Sassafras River MD SASOH2 95 0.5 Upper Chester River MD CHSTF 1 0.5 Middle Chester River MD CHSOH 77 0.5 Lower Chester River MD CHSMH 2,928 1.0 Eastern Bay MD EASMH 6,209 2.0 Middle Choptank River MD CHOOH 72 0.5 Lower Choptank River MD CHOMH2 1,621 1.0 Mouth of Choptank River MD CHOMH1 8,184 2.0 Little Choptank River MD LCHMH 4,076 2.0 Honga River MD HNGMH 7,761 2.0 Fishing Bay MD FSBMH 197 0.5
Middle Nanticoke River MD NANOH 12 0.5
Lower Nanticoke River MD NANMH 3 0.5
Wicomico River MD WICMH 3 0.5
Manokin River MD MANMH1 4,294 2.0
Manokin River MD MANMH2 59 0.5 Big Annemessex River MD BIGMH1 2,021 2.0 Big Annemessex River MD BIGMH2 22 0.5
Lower Pocomoke River MD POCMH_MD 877 1.0
Lower Pocomoke River VA POCMH_VA 4,066 1.0 Tangier Sound MD TANMH1_MD 24,683 2.0 Tangier Sound MD TANMH2_MD 74 0.5 Tangier Sound VA TAHMH_VA 13,579 2.0 Sources: USEPA 2003d, 2004e; Code of Ma ryland Title 26 Subtitle 08, Chapter 2, Section 3; Code of Virginia 9 62.1- 44.15 3a; VAC 25-260-185; 7 Delaware Code section 6010 ; 7 Delaware Administrative Code 7401; District of Columbia Municipal Regulations Title 21, Chapter 11. Notes: This table contains additional split segments beyond the 92 Chesapeake Bay s egments listed in Table 3-3 strictly for purposes of applying separate water clarity criteria application depths within the same Bay segment (USEPA 2004e). If a Bay segment was listed in Table 3-3, but it is not listed here, that entire Bay segment has been delineated as a SAV no-grow zone and the shallow-water bay grass does not apply (USEPA 2004e).Chesapeake Bay TMDL



### 3.2 JURISDICTIONS’ CURRENT CHESAPEAKE BAY WATER QUALITY STANDARDS REGULATIONS Delaware, the District of Columbia, Maryland, and Virginia each has adopted WQS consistent with EPA’s published Chesapeake Bay water quality criteria, assessment procedures, and tidal water designated uses in its respective WQS regulations ( Table 3-7 ). In some cases, a jurisdiction also adopted jurisd iction-specific designated uses or criteria or both; those cases are briefly described below.

Table 3-7. Links for accessing the current waters quality standards (WQS) regulations for Delaware, the District of Columbia, Maryland, and Virginia

Jurisdiction WQS regulations URL address
Delaware 7 Delaware Code Section 6010; 7 Delaware Administrative Code 7401

< http://www.epa.gov/waterscience/sta ndard s /wqslibrary/de/de_3_wqs.pdf > District of Columbia DC Municipal Regulations Title 21, Chapter 11

< http://www.epa.gov/waterscience/standards/wqslibrary/dc/dc_3_register.pdf > Maryland Code of Maryland Title 26 Subtitle 08, Chapter 2

< http://www.epa.gov/waterscience/standards/wqslibrary/dsd.state.md/md-ch2-quality20051130.pdf.us/comar/subtitl e_chapters/26_ Chapters.htm > Virginia Code of Virginia 9 62.1-44.15 3a; VAC 25-260 Virginia WQSs

< http://www.deq.virginia.gov/wqs/ > OR

< http://epa.gov/waterscience/standard s/wqslibrary/va/va_3_ wq s.pdf >



### 3.2.1 Delaware Delaware has adopted all the EPA-published Ch esapeake Bay criteria, assessment procedures, designated use documents, and subsequent addenda listed in Table 3-1 by reference into its WQS regulations. The EPA-published Chesapeake Bay cr iteria, assessment procedures, and designated use docume nts and subsequent addenda apply to the tidal Nanticoke River and Broad Creek in Delaware, both of which are subject to this Chesapeake Bay TMDL (see Table 2-1 ). Delaware has also adopted EPA’s narrative chlorophyll a water quality criteria.



### 3.2.2 District of Columbia

The District of Columbia has adopted all the EPA-publis hed Chesapeake Bay criteria, assessment procedures, designated use docum ents, and subsequent addenda listed in Table 3-1 by reference into its WQS regulations. Table 3-8 summarizes the Distric t of Columbia’s designated uses for its surface waters. The Distri ct of Columbia has adopted EPA’s narrative chlorophyll a water quality criteria but also adopted the numeric chlorophyll a water quality criteria shown in Table 3-9 with respect to the District of Co lumbia’s tidal Class C waters ( those designated for the protection and propagation of fish, shellfish, and wildlife). Those numeric chlorophyll a criteria are subject to this Chesapeake Bay TMDL (see Table 2-1 ).

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‐ 15 December 29, 2010Chesapeake Bay TMDL

3

‐ 16 December 29, 2010 Table 3-8. District of Columbia designated uses for surface waters
Class of water Description
A Primary contact recreation
B Secondary contact recreation and aesthetic enjoyment
C Protection and propagation of fish, shellfish, and wildlife
D Protection of human health related to consumption of fish and shellfish
E Navigation Source: District of Columbia Municipal Regulations Title 21, Chapter 11

Table 3-9. Numeric criteria for the District of Columbia’s tidally influenced waters

Constituent Numeric criteria Temporal application Designated

use Dissolved oxygen 7-day mean ≥ 6.0 mg/L Instantaneous minimum ≥ 5.0 mg/L

30-day mean ≥ 5.5 mg/L

7-day mean ≥ 4.0 mg/L Instantaneous minimum ≥ 3.2 mg/L (At temperatures > 29 °C, in tidally influenced waters, an instantaneous minimum DO concentration of 4.3 mg/L will apply) February 1–May 31

June 1–January 31 C

Secchi depth 0.8 m (seasonal segment average) April 1–October 31 C Chlorophyll a 25 μg/L (season segment average) July 1–September 30 C Source: District of Columbia Municipal Regulations Title 21, Chapter 11 Note: μg/L = micrograms per liter



### 3.2.3 Maryland Maryland has adopted into its WQS regulations al l the EPA-published Chesapeake Bay criteria, assessment procedures, and designated uses documen ts, and subsequent addenda listed in Table 3-1. These WQS apply to all Chesapeake Bay, tidal tributary and embayment waters of Maryland, all of which are subjec t to this Chesapeake Bay TMDL (see Table 2-1). Maryland has also adopted EPA’s narrative chlorophyll a water quality criteria.

Several tidal Bay segment-specific applications of DO criteria are uniqu e to Maryland. In the middle-central Chesapeake Bay segment (CB4MH), restoration variances 1 of 7 and 2 percent apply to the application of the deep-water and deep-channe l designated use DO criteria, respectively. In the Patapsco River segment (P ATMH), a restoration variance of 7 percent applies to the applicat ion of the deep-water designated us e DO criteria. In the lower Chester River segment (CSHMH), a restor ation variance of 14 pe rcent applies to the application of the deep-channel designated use DO criteri on (COMAR 26.08.02.03-3(c)(8)(e)(vi). These restoration variances are consistent with EPA-published guidance (USEPA 2003d) and were

1 A restoration variance is the percentage of allowable exceedance of a WQS based on water quality modeling incorporating the best available data and assumptions. The restoration variances are tem porary and will be reviewed at a minimum every 3 years, as required by the CWA and EPA regulations. The variances could be modified on the basis of new data or assumptions incorporated into the water quality model. CO MAR 26.08.02.03-3(C)(8)(h).Chesapeake Bay TMDL

approved by EPA on August 29, 2005 in the case of the two mainstem Bay and Patapsco River segments and December 27, 2010 in the case of the lower Chester River segment.

In the tidal upper and middle Pocomoke River segments (POCTF, POCOH_MD), because of the seasonal lower DO concentration from the natura l oxygen-depleting processes present in the extensive surrounding tidal wetlands , Maryland adopted a site-specifi c criterion of greater than or equal to 4 mg/L 30-day mean DO, consis tent with the EPA-pub lished criterion (USEPA 2004a), and approved by EPA on December 27, 2010.



### 3.2.4 Virginia Virginia has adopted into its WQS regulations all the EPA-published Ba y criteria, assessment procedures, designated uses documents, and subse quent addenda listed in Table 3-1. These WQS apply to all Chesapeake Bay, tidal tributary and embayment waters of Virginia, all of which are subject to this Chesapeake Ba y TMDL. The narrative chlorophyll a criteria guidance published by EPA (USEPA 2003a) was adopted by Virginia for application to Virginia ’s Bay tidal waters. Virginia also adopted the segm ent-specific numeric chlorophyll a criteria for the tidal James River listed in Table 3-10 into its WQS regulations. The criter ia are based on various scientific lines of evidence published in the original EPA 2003 Bay criteria document (USEPA 2003a) with additional river-specific considerations (VADEQ 2004). EPA approved Virginia’s WQS regulations on June 27, 2005 and approved a dditional amendments on December 28, 2010.

Table 3-10. Segment-specific chlorophyll a criteria for Virginia’s tidal James River waters

Designated

use Chlorophyll a criterion

( μ g/L) Chesapeake Bay segment Temporal application

10 Upper James River-Upper (JMSTF2)
15 Upper James River-Lower (JMSTF1)
15 Middle James River (JMSOH)
12 Lower James River (JMSMH)
12 Mouth of the James River (JMSPH) March 1–May 31

15 Upper James River-Upper (JMSTF2)
23 Upper James River-Lower (JMSTF1)
22 Middle James River (JMSOH)
10 Lower James River (JMSMH) Open-Water

10 Mouth of the James River (JMSPH) July 1–September 30

Source: Code of Virginia 9 section 62.1-44.15 3a; VAC 25-260 Note: μg/L = micrograms per liter

Virginia has additional site -specific DO and chlorophyll a criteria. In the tidal Mattaponi (MPNTF, MPNOH) and Pamunkey (PMKTF, PMKOH) river segments, because of the seasonal lower DO concentration from the natural oxygen- depleting processes present in the surrounding extensive tidal wetlands, Virginia adopted a site-s pecific criterion of great er than or equal to 4 mg/L 30-day mean DO (9 VAC 25-260-185), cons istent with the EPA-published criterion (USEPA 2004a) and approved by EPA on June 27, 2005.

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‐ 17 December 29, 2010Chesapeake Bay TMDL



### 3.3 ASSESSING ATTAINMENT OF CHESAPEAKE BAY WATER QUALITY STANDARDS The Bay criteria assessment approach is designed to protect the living resources as defined by the designated uses (USEPA 2003a). The criteria levels themselves were largely based on scientific studies performed in laboratory se ttings or under controll ed field conditions. The criteria establish the level of a given habitat condition that living resources need for survival. They do not account for many other environmen tal factors that coul d affect survival.

For all four tidal jurisdictions, attainment of each jurisdiction’s Chesapeake Bay WQS is determined by applying the same set of assessm ent procedures published in the original 2003 Chesapeake Bay criteria document (USEPA 2003a ) and subsequent published addenda (USEPA 2004a, 2007a, 2007b, 2008a, 2010a) (see Table 3-1 ). Those consistent sets of criteria assessment procedures were formal ly adopted into each jurisdiction’s WQS regulations by reference.



### 3.3.1 Defining Total Exceedances
Criteria attainment for DO, water clarity, and chlorophyll a is assessed in term s of the spatial and temporal extent of criterion exceedances—wha t volume or surface area of the Bay segment exceeds a given criterion and for how much time during the assessment period (USEPA 2003a, 2004a). The allowable frequency with which crite ria can be violated without a loss of the designated use is also considered. For each lis ting cycle, assessments are based on monitoring data collected over a 3-year period in each spa tial assessment unit. Spatial assessment units are defined by Chesapeake Bay segments and applicab le designated uses. Such assessment of the criteria as further described be low is designed to provi de reliable protection for the associated refined aquatic life use.

The spatial exceedances of criteri a are determined using a grid cell-based data interpolation software application that enable s estimation of water quality values for the entire Bay using monitored data at specific points (USEPA 2003a, 2007a). The interpolated data are compared to water quality criteria on a cell by cell basis, and the percent of surface area or volume exceeding the criterion in each spatial asse ssment unit is calculated. The percent spatial exceedances for each assessment unit are then compiled for each monitoring event conducted during the 3-year monitoring period.

The temporal extent of exceedances is determined by calculating the probability that an observed percent exceedance will be equaled or exceeded. To calculate that probability, the percent of spatial exceedances are sorted and ranked, and a cumulative probability is calculated for each spatial exceedance value (USEPA 2003a). An example is shown in Table 3-11

. The spatial and temporal exceedances can be grap hically illustrated by plotting the cumulative frequency distribution (CFD) curve, which is a plot of the temporal exceedance values on the Y-axis versus the spatial exceedance values (i n area or volume) on the X-axis (Figure 3-3) (USEPA 2003a, 2007a; STAC 2006).

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‐ 18 December 29, 2010Chesapeake Bay TMDL

Table 3-11. Estimated percent spatial criteria exceedances and associated cumulative probabilities

Period of data Percent area/volume exceeding criteria (spatial) Rank Cumulative probability [rank / (n + 1)] (temporal)
100 0.00% June 1998 75 1 7.69% March 1998 72 2 15.38% May 1999 67 3 23.08% May 1998 65 4 30.77% April 1998 55 5 38.46% June 2000 50 6 46.15% March 1999 49 7 53.85% April 2000 39 8 61.54% May 2000 35 9 69.23% Apr 1999 34 10 76.92% June 1999 25 11 84.62% March 2000 20 12 92.31%
Source: USEPA 2003a

Source: USEPA 2003a

Figure 3-3. Example cumulative frequency distribution (CFD) curve.

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‐ 19 December 29, 2010Chesapeake Bay TMDL



### 3.3.2 Defining Allowable Exceedances EPA developed reference curves for each wate r quality criterion (DO, water clarity, and chlorophyll a ) to provide a scientifically based, dire ct measure of the time and space during which a particular criterion can be allowably exce eded – i.e., without resulting in harm to the designated uses(s) (USEPA 2003a). Those allowabl e exceedances are defined to be those that last a short enough time or cover a small enough volume/surface area to have no adverse effects on the designated use. It is assumed that the de signated uses can be attained even with some limited level of criteria exceedan ces and, thus, the reference cu rves define those criteria exceedances deemed to be allowable—chronic in time but over small volumes/surface areas, or infrequent occurrences over large volumes/surface areas. Exceedances that occur over large areas of space and time would be expected to have significant detrimental effects on biological communities, which would imply nona ttainment of designated uses.

For assessment purposes, EPA developed two types of reference curves: a biological reference curve and a 10 percent default reference curve for use when a biological reference curve is unavailable.

Biological reference curves are CFDs develope d for a given criterion in areas for which monitoring data are available and in which h ealthy aquatic communities exist (USEPA 2003a). They represent the range of conditions that can reasonably be expected in a healthy community. As a result, the biological reference curve can be used to provide an unde rstanding of what level of criteria exceedances are allo wable without losing support of the designated use. Given the Bay’s nutrient-enriched status , however, appropriate referenc e sites are limited. Biological reference curves have been published for and are used to assess allowable exceedances for the deep-water DO criteria (USEPA 2010a) and th e water clarity crit eria (USEPA 2003a).

In some cases, developing a biologically based reference curve is not possible because of a lack of data describing the health of the relevant species or biol ogical communities and lack of appropriate reference sites. In those cases, EPA used a 10 percent default reference curve (USEPA 2007a). The 10 percent de fault reference curve is define d as a hyperbolic curve that encompasses no more than 10 percent of the area of the CFD graph (percent of space multiplied by percent of time) (USEPA 2007a, page 13, Figure II-4 and Equation 1) ( Figure 3-4 ).

Once the CFD curve for a spatial assessm ent uni t is developed from monitoring data (also referred to as the assessment curve), it is compar ed to the appropriate reference curve. The area on the graph above the reference curve (blue line) and below the assessmen t curve (red line) is considered a non-allowable exceedance. The ar ea below the referenc e curve (yellow) is considered an allowable exceedance ( Figure 3-5 ).

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‐ 20 December 29, 2010Chesapeake Bay TMDL

Source: USEPA 2007a

Figure 3-4. Default reference curve used in the attainment assessment of Chesapeake Bay water quality criteria for which biologically based reference curves have not yet been derived.

Source: USEPA 2003a

Figure 3-5. Example reference and assessment curves showing allowable and non-allowable exceedances.

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‐ 21 December 29, 2010Chesapeake Bay TMDL



### 3.3.3 Assessing Criteria Attainment

Dissolved Oxygen Criteria Assessment EPA published DO criteria protective of migrator y fish spawning and nursery, open-water fish and shellfish, deep-water seasonal fish a nd shellfish, and deep-c hannel seasonal refuge designated use habitats. DO criteri a were established for the Ches apeake Bay that varied in space and time to provide levels of protection for di fferent key species and communities (Table 3-4). The criteria also were designe d around several lengths of time to reflect the varying oxygen tolerances for different life stages (e.g., larval, juvenile, adult) and effects (e.g., mortality, growth, behavior) (USEPA 2003a).

The DO criteria include multiple components, including the target DO concentration, the duration of time over which the c oncentration is averaged, the designated use area where the criterion applies, the protecti on provided, and the time of year when the criterion applies (USEPA 2003a, 2003d). The four tidal Bay jurisd ictions adopted these DO criteria into their respective WQS regulations.

Assessing DO criteria attainment is challenging b ecause of the complexity of both the criteria and the Bay itself. To fully assess all the criteria components, data needed to be collected at a spatial intensity that adequately represents the four designated use habitats of Chesapeake Bay tidal waters at different times of the year (USEPA 2003c, 2004e ). Similarly, data were collected during all the applicable seasons and at frequencies sufficient to address the various criteria duration components.

The different DO criteria apply to different designat ed use areas and multiple criteria apply to the same designated use area. The DO criteria comp onents also apply over different periods to protect species during critical life stages or during particularly stressful times of the year. To fully assess each DO component in each designated use habitat over the appropriate periods will require an extensive monitoring program a nd a detailed assessment methodology. The CBP conducts extensive water quality and living reso urce monitoring throughout the Bay tidal waters (CBP 1989a, 1989b; MRAT 2009). The existing Bay wa ter quality monitoring was not sufficient to cover all the criteria components, however , and some details in the assessment methodology remain unresolved (USEPA 2007a; MRAT 2009).

The DO criteria include 30-day, 7- day, and 1-day means along with an instantaneous minimum. The CBP partners have the capacity (data, publ ished assessment methodology) to assess only the 30-day mean open-water and deep-water DO criteria and, in the case of the deep-channel use, the instantaneous minimum DO criteria (U SEPA 2003a, 2004a, 2007a, 2008a, 2010a). The remaining DO criteria were not assessed because the existing water quality monitoring programs and the published assessment methodologies are not yet adequate for full assessment.

Evaluation of the Chesapeake Bay Water Quality and Sediment Transport Model’s outputs have provided clear evidence that the 30-day mean ope n-water and deep-water and the instantaneous minimum deep-channel DO criteria are the criteria driving determ ination of nutrient loadings supporting attainment all the open-water (30-da y mean, 7-day mean, instantaneous minimum), deep-water (30-day mean, 1-day and instantane ous minimum), and deep-channel (instantaneous minimum) DO criteria.

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‐ 22 December 29, 2010Chesapeake Bay TMDL

For both open-water and deep–water designated uses, the 30-day m ean criteria had the highest nonattainment in all three scenar ios illustrated in Figure 3-6. The 30-day mean open-water and deep-water criteria are, theref ore, protective of the other non -assessed DO criteria (open-water 7-day and instantaneous minimu m, deep-water 1-day mean and instantaneous minimum) on average for the mainstem Bay segments. Th e deep–channel designated use has only one DO criterion, and it is currently as sessed using monitoring data. The deep-channel criterion is also more protective, based on the levels of nonatta inment recorded in Figure 3-6, than the deepwater and open-water criteria. The analyses documented in Appendix D provide clear evidence the 30-day mean open-water, 30-day mean deep-water DO criteria, and the deep-channel instantaneous minimum criterion are the most pr otective criteria across all Bay segments and designated uses.

Chlorophyll a Criteria Assessment The procedures described in USEPA 2007b, and further refined in USEPA 2010a, apply to assessing Virginia’s tidal James River and the District of Columbia’s tidal waters numeric chlorophyll a criteria.

To assess attainment of the Virginia and th e District of Columbia’s adopted numerical chlorophyll a concentration-based criteria, it was necessa ry to establish a reference curve for use in the CFD criteria assessment (USEPA 2003a, 2007a ). In the case of th e numerical chlorophyll

a criteria where a biologically based refere nce curve is not available (USEPA 2007b), EPA recommends—and Virginia and the District of Columbia adopted—using the 10 percent default reference curve originally described in USEPA 2007a and illustrated in Figure 3-4

. The jurisdiction-adopted, c oncentration-based chlorophyll a criteria value s are threshold concentrations that should be exceeded infrequently (< 10 percent) because a low number of naturally occurring exceedances occur even in a healthy phy toplankton population (USEPA 2007b). The assessment of chlorophyll a criteria attainment, therefore, uses the CFD-based assessment method described earlier that applies the 10 percent default re ference curve. Such concentration-based Chesapeake Bay chlorophyll a criteria apply only to those seasons and salinity-based habitats for which they were defi ned to protect against applicable human health and aquatic life impairments (USEPA 2007b). Each season—Spring (March 1–May 31) and Summer (July 1–September 30)—was assess ed separately to evaluate chlorophyll a criteria attainment.

The chlorophyll a criteria are based on seasonal mean s of observed ch lorophyll data. The observed data are first transformed by taking the na tural logarithm and then interpolated spatially to equally spaced points (representing interpolator cells) within the designated use area for each monitoring cruise. The interpolated value of each cell is averag ed in time across the entire season, and then the spatial violati on rate is calculated as the fract ion of interpolator cells in a designated use area that fails the appropriate criterion (USEPA 2010a).

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‐ 23 December 29, 2010Chesapeake Bay TMDL

Source: Appendix D

Figure 3-6. Direct model assessment of open water (a), and deep water and deep channel (b) criteria.

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‐ 24 December 29, 2010Chesapeake Bay TMDL

3

‐ 25 December 29, 2010 SAV/Water Clarity Criteria Assessment Water clarity criteria and SAV restoration acreages are used to define attainment of the shallowwater Bay grass designated use in the Chesapeak e Bay, its tidal tributaries and embayments (USEPA 2003a, 2003d). EPA published three measures for assessing attainment of the shallowwater SAV designated use for a Chesapeake Bay segment (USEPA 2007a):
1. Measure S AV acreage in the Bay segment from overflight data mapping analysis and compare with the SAV restoration goal acreage for that Bay segment (USEPA 2003d).
2. Measure w ater clarity acreage on the ba sis of routine water quality mapping using data from the Chesapeake Bay shallow-water monitoring program and, combined with measured acres of SAV, compare with the calculated water clarity acres for that segment (USEPA 2007a).
3. Measure w ater clarity criteria attainme nt on the basis of the CFD assessment methodology, again, using shallow-water monitoring program data (USEPA 2003a, 2003d, 2007a, 2008a).

Without sufficient shallow-water monitoring data to determine the availa ble water clarity acres (measurement 2 above) or to assess water clarity criteria attainment using the CFD-based procedure (measurement 3 above), EPA recommends that the jurisdictions assess shallow-water Bay grass designated use attainment using th e acres of mapped SAV (measurement 1 above) (USEPA 2003a, 2003d, 2007a, 2008a).Chesapeake Bay TMDL



## SECTION 4. S OURCES OF NITROGEN, PHOSPHORUS AND SEDIMENT TO THE CHESAPEAKE BAY

Nitrogen, phosphorus, and sediment loads originat e from many sources in the Bay watershed. Point sources of nitrogen, phosphorus, and sedime nt include municipal wastewater facilities, industrial discharge facilities, CSOs, SSO s, NPDES permitted stormwater (MS4s and construction and industrial sites), and CAFOs. Nonpoint sources incl ude agricultural lands (AFOs, cropland, hay land, and pasture), atmosphe ric deposition, forest lands, on-site treatment systems, nonregulated stormwater runoff, stream banks and tidal shorelines, tidal resuspension, the ocean, wildlife, and natural background. Unle ss otherwise specified, the loading estimates presented in this section are based on result s of the Phase 5.3 Chesap eake Bay Watershed Model (Bay Watershed Model). For a description of the Bay Watershed Model, see Section 5.8. Estimates of existing loading conditions are based on the 2009 scenario run through the Bay Watershed Model.



### 4.1 JURISDICTION LOADING CONTRIBUTIONS Analysis of 2009 monitoring data and estimated modeling results shows that Pennsylvania provided the largest proportion of nitrogen loads delivered to the Bay (44 percent), followed by Virginia (27 percent), Maryland ( 20 percent), New York (4 percen t), Delaware (2 percent) and West Virginia (2 percent), and the Di strict of Columbia (1 percent) ( Figure 4-1 ). Delivered loads are the amount of a pollutant deliv ered to the tidal wate rs of the Chesapeake Bay or its tributaries from an upstream point. Delivered loads differ from edge-of-stream loads becauese of in-stream processes in free-flowing rivers that naturally remove nitroge n and phosphorus from the system.

DE 2% DC 1%

MD 20%

NY 4%

PA 44% VA 27% WV 2% 

### Total Nitrogen

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-1. Modeled estimated total nitrogen loads deli vered to the Chesapeake Bay by jurisdiction in 2009.

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‐ 1 December 29, 2010Chesapeake Bay TMDL

The model estimated phosphorus loads delivered to the Bay were dominated by Virginia (43 percent), followed by Pennsylvania (24 percent) , Maryland (20 percent), New York (5 percent), West Virginia (5 percent), Delaware (2 percent) , and the District of Columbia (1 percent) ( Figure 4-2 ).

DE 2% DC 1%

MD 20%

NY 5%

PA 24% VA 43% WV 5% 

### Total Phosphorus

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario
Figure 4-2. Model estimated total phosphorus loads delivered to the Chesapeake Bay by jurisdiction in 2009.
Similar to the phosphorus loads, 2009 model estima ted sediment loads delivered to the Bay are dominated by Virginia (41 percent), followe d by Pennsylvania (32 pe rcent), Maryland (17 percent), West Virginia (5 percen t), New York (4 percent), Delaware (1 percent), and the District of Columbia (< 1 percent) ( Figure 4-3 ).

DE 1% DC, <1%

MD 17%

NY 4%

PA 32% VA 41% WV 5% 

### Total Sediment

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario Figure 4-3. Model estimated total sediment loads delivered to the Chesapeake Bay by jurisdiction in 2009.

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‐ 2 December 29, 2010Chesapeake Bay TMDL



### 4.2 MAJOR RIVER BA SIN CONTRIBUTIONS The major river basins’ model-estimated contribu tions of total nitrogen loads delivered to the Bay in 2009 are illustrated in Figure 4-4 . The Susquehanna River ba sin, draining parts of New York, Pennsylvania, and Maryland, is estimated to be responsible for almost half of the nitrogen loads delivered to the Bay (46 percent). The next major contributor, at 22 percent, is the Potomac River Basin, draining the entire District of Columbia and parts of Maryland, Pennsylvania, Virginia, and West Virginia. The James River Basin (draining parts of Virginia and West Virginia) contributes 12 percent of the nitrogen loads to the Bay; the Eastern Shore Basin (draining parts of Delaware, Mary land, and Virginia) contibutes 8 percent of the nitrogen loads to the Bay; and the Western Shore Basin (drain ing parts of Maryland) is estimated to be responsible for 6 percent of the nitrogen load ing to the Bay. Smaller portions, 3 percent, 2 percent, and 1 percent are contributed by the Rappahannock (Virginia), the York (Virginia) and the Patuxent (Maryland) ri ver basins, respectively ( Figure 4-4 ).

8%

12%
1%

22%

3% 46% 6% 2% 

### Total Nitrogen

Eastern Shore of Chesapeake Bay

James River Basin

Patuxent River Basin

Potomac River Basin

Rappahannock River Basin Susquehanna River Basin

Western Shore of Chesapeake Bay

York River Basin

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-4. Model estimated total nitrogen loads delivered to the Chesapeake Bay by major tributary in 2009.
The major river basins’ model estimated contribu tions to total phosphorus loads to the Bay in 2009 are illustrated in Figure 4-5 . Three river basins—the Potomac (27 percent), the Susquehanna (26 percent), and the James (20 per cent)—are estim ated to account for about threequarters of the total phosphorus loading to the Bay. The Eastern Shore contributes 10 percent of the total phosphorus load, while the balance is provided by the Rappahannock (6 percent), the Western Shore (5 percent), the York (4 percent) , and the Patuxent (2 percent) river basins ( Figure 4-5 ).

The major river basins’ model estimated contributi ons to total sediment loads to the Bay in 2009 are illus trated in Figure 4-6 . The Susquehanna (33 percent) and Potomac (32 percent) river basins are estim ated to contribute the majority of the total sediment loads delivered to the Chesapeake Bay, followed by the James (16 percen t) and the Rappahannoc k (9 percent) river

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‐ 3 December 29, 2010Chesapeake Bay TMDL

basins. The Eastern Shore (4 per cent), Western Shore (3 percent), York (2 percent) and Patuxent (1 percent) river basins e ach contribute relatively small total sediment loads ( Figure 4-6 ).

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-5. Model estimated total phosphorus loads delivered to the Chesapeake Bay by major tributary in 2009.

4%

16%

1%

32%

9% 33% 3% 2% 

### Total Sediment

Eastern Shore of Chesapeake Bay

James River Basin

Patuxent River Basin

Potomac River Basin

Rappahannock River Basin Susquehanna River Basin

Western Shore of Chesapeake Bay

York River Basin 10%

20%

2%

27% 6% 26% 5% 4% 

### Total Phosphorus

Eastern Shore of Chesapeake Bay

James River Basin

Patuxent River Basin

Potomac River Basin

Rappahannock River Basin
Susquehanna River Basin

Western Shore of Chesapeake Bay

York River Basin

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-6. Model estimated total sediment loads delivered to the Chesapeake Bay by major tributary in 2009.

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‐ 4 December 29, 2010Chesapeake Bay TMDL



### 4.3 POLLUTANT SOURCE SECTOR CONTRIBUTIONS

Table 4-1 and Table 4-2 provide model estimates of major pollutant sources of nitrogen and phosphorus, respectively, delivered to the Bay by each ju risdiction and by each major pollutant source sector. Nontidal deposition refers to atmospheric deposition direct to nontidal surface waters (e.g., streams, rivers). Table 4-3 provides estimates of major sediment sources by jurisdiction and by major pollu tant source sector and represents the portion of sediment that is from land-based sources. Stream erosion is al so a significant source of watershed sediment delivered to the Bay. Sufficient data do not exis t to accurately quantify the portion of the total sediment load specifically from stream erosion.

Table 4-1. Percentage of total nitrogen delivered to the Bay from each jurisdiction by pollutant source sector

Jurisdiction Agriculture Forest Stormwater runoff Point

source Septic Nontidal deposition
Delaware 3% 1% 1% 0% 2% 1%
District of Columbia 0% 0% 1% 5% 0% 0% Maryland 16% 14% 28% 27% 36% 27%
New York 4% 7% 3% 3% 5% 5% Pennsylvania 55% 46% 33% 25% 30% 42% Virginia 20% 27% 33% 39% 24% 25% West Virginia 3% 4% 2% 1% 2% 1%
Total 100% 100% 100% 100% 100% 100% Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario Note: Nontidal deposition refers to atmospheri c deposition direct to nontidal surface waters.

Table 4-2. Percentage of total phosphorus delivered to the Bay from each jurisdiction by pollutant source sector

Jurisdiction Agriculture Forest Stormwater runoff Point

source Septic Nontidal deposition
Delaware 4% 1% 1% 0% 0% 0%
District of Columbia 0% 0% 1% 2% 0% 0% Maryland 19% 14% 28% 21% 0% 27%
New York 5% 7% 3% 5% 0% 5% Pennsylvania 24% 25% 16% 28% 0% 27% Virginia 42% 45% 50% 42% 0% 38% West Virginia 6% 7% 2% 3% 0% 2%
Total 100% 100% 100% 100% 100% 100% Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario Note: Nontidal deposition refers to atmospheric depositio n direct to nontidal surface waters. Although the percentage contribution of phosphorus from nontidal deposition is pr ovided here, the overall amount of phosphorus contributed from nontidal deposition is considered to be insignificant.

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‐ 5 December 29, 2010Chesapeake Bay TMDL

4

‐ 6 December 29, 2010 Table 4-3. Percentage of sediment delivered to the Bay from each jurisdiction by pollutant source sector

Jurisdiction Agriculture Forest Stormwater runoff Point

source Septic Nontidal deposition
Delaware 1% 0% 1% 0% -- -- District of Columbia 0% 0% 1% 27% -- -- Maryland 15% 13% 32% 11% -- -- New York 3% 8% 4% 3% -- -- Pennsylvania 35% 34% 21% 23% -- -- Virginia 41% 40% 39% 35% -- -- West Virginia 5% 5% 3% 1% -- -- Total 100% 100% 100% 100% -- -- Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario Note: Only land-based sources of sediment were included in this table. Septic sources discharge to groundwater and nontidal deposition refers to atmospheric depo sition direct to nontidal surface waters.

The following sections provide ad ditional details regarding the ma jor pollutant source sectors, including descriptions of the extent/magnitude of the pollutant source, geographic distribution, and long-term trends relevant to the source sector. The significan ce of the source sector in terms of loading to the Bay relative to other sources is also discussed.



### 4.4 REGULATED POINT SOURCES Point sources are defined as any “discernable, confined, and discrete conveyance, including...any pipe, ditch, channel, tunnel, condui t, well, discrete fissure, contai ner, rolling stoc k, concentrated animal feeding operation, landfill leachate collection system, or vessel or other floating craft, from which pollutants are or may be discha rged” [CWA section 502( 14), 40 CFR 122.2]. That definition does not include agricultural stormwater discharges or return flows from irrigated agriculture, which are exempt fr om the definition of point source under the CWA. The NPDES program, under CWA sections 318, 402, and 405, require s permits for the discharge of pollutants from point sources.

Two issues that directly affect modeling of the regulat ed point sources in the Bay watershed are the size of facility flows and permitted discha rge limits. For purposes of the Chesapeake Bay TMDL analysis and modeling, regulated point so urces in the Chesapeake Bay watershed have been evaluated under the following categories 1 :

 Municipal wastewater facilities

 Industrial wastewat er facilities

 CSOs

 NPDES permitted stormwater (MS4s, industrial, and construction)

 NPDES permitted CAFOs

1 The universe of regulated point sources may change over time due to such actions as designation, compliance evaluation, or new permitting activities.Chesapeake Bay TMDL

The remainder of this section outlines the dis tinctions between signifi cant and nonsignificant municipal and industrial wastewater discharge facilities in the Bay watershed, explains how the facilities were addressed in modeling, discusse s the effect of the basinwide nitrogen and phosphorus permitting approach on point source modeling for the TMDL, and provides a summary of model-estimated loads associated with each of the regulated point source categories of nitrogen, phosphorus, and sediment to the Bay. Appendix Q includes the regulated point sources accounted for in the Bay TMDL.



### 4.4.1 Significant and Nonsignificant Municipal and Industrial Facilities Municipal and industrial wastewat er discharge facilities are ca tegorized as significant or nonsignificant primarily on the basis of permitted or existing flow characte ristics and comparable loads in the case of industrial discharge facilities. The Bay ju risdictions define significant facilities as outlined in Table 4-4

.

Table 4-4. Jurisdiction-specific definitions of significant municipal and industrial wastewater discharge facilities

Jurisdiction Municipal wastewater facilities (million gallons per day) Industrial wastewater facilities (estimated loads, pounds per year)
Delaware Design flow ≥ 0.4
District of Columbia Blue Plains WWTP Maryland Design flow ≥ 0.5
New York Design flow ≥ 0.4 Pennsylvania Existing flow ≥ 0.4 Design flow ≥ 0.5 a Design flow ≥ 0.1 b Virginia

New facilities ≥ 0.04 c West Virginia Design flow ≥ 0.4 ≥ 3,800 total phosphorus

or ≥ 27,000 total nitrogen

Source: USEPA 2010b Notes: a. Above the fall line/tidal line; b. Below the fa ll line/tidal line; c. Also includes expansion of flows ≥ 0.04 mgd.

Jurisdictions also may identify sp ecific facilities as significant in their WIPs (USEPA 2009c). Facilities not meeting the above criteria, and not othe rwise identified in th e jurisdictions’ WIPs, are considered nonsignificant facilities. Table 4-5 provides a jurisdictional breakdown of municipal and industrial disc harging facilities in the Chesapeake Bay watershed.

For the TMDL, facilities were rep resented using various flow and discharge concentrations depending on their status as significant or nonsignificant. Significan t facilities received individual WLAs, except for New York and the Vi rginia James River Basi n, which received an aggregate WLA. The New York WLA for wastewat er is discussed further in Section 8.4.4, and the James River Basin WLA is discussed further in Appendix X. Nonsignificant facilities were generally included in the aggr egate WLAs by Bay segment wate rshed (USEPA 2009c) and are discussed further in Section 8.3.3.

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‐ 7 December 29, 2010Chesapeake Bay TMDL

Table 4-5. Significant and nonsignificant municipal and industrial wastewater discharging facilities by jurisdiction as of December 2010 Significant facility Nons ignificant facility Jurisdiction Municipal Industrial Total Municipal Industrial Total Total Facilities

DC a 1 0 1 1 9 10 11
DE 3 1 4 1 1 2 6
MD 75 12 87 163 477 640 727
NY 26 2 28 26 45 71 99
PA 183 30 213 1246 409 1655 1868
VA 101 24 125 1618 639 2257 2382
WV b 13 7 20 125 23 148 168
Total 402 76 478 3180 1603 4783 5261 Source: Facilities identified in the final phase 1 WIPs Notes: a. Blue Plains WWTP serves DC and parts of MD and VA, but is only counted once. b. Multiple facilities (4) share one NPDES permit in West Virginia.



### 4.4.2 Basinwide NPDES Permitting Approach In 2004 EPA and the Bay watershed jurisdictions agreed to take a consistent approach to permitting all the significant municipal and industrial wastewater discharging facilities contributing nitrogen and phosphorus to the Ches apeake Bay watershed (U SEPA 2004d). As part of that approach and on the basis of the jurisd ictions’ revised Chesapeake Bay WQS, permits are to be reissued with nitrogen and phosphorus lim its that are sufficient to achieve Bay WQS and that are consistent with the jurisdictions’ tri butary strategies. The basinwide permitting approach also contains additional specific provisions fo r permitting of nitrogen and phosphorus in the Bay watershed, including the following:

 Annual load limits—Unless such expressions would be impracticable, EPA’s regulations require NPDES permits for non-publicly owned treatment works to express effluent limits as maximum daily and average monthly lim its [40 CFR 122.45(d)(1)] and require NPDES permits for POTWs to express effluent limits as average weekly and average monthly limits [40 CFR 122.45(d)(2)]. In the case of the Chesapeake Bay permitting for nitrogen and phosphorus, EPA has determined that because of the long hydraulic durations in the Bay, and the fact that the control of annual lo ading levels of nitrog en and phosphorus from wastewater treatment plants is much more releva nt and appropriate in terms of the effect of nitrogen and phosphorus on Bay water quality crit eria than daily maximums or weekly or monthly averages, expression of nitrogen and phos phorus effluent limits in short periods is impracticable and that, therefore, such effluent limits may be expressed as an annual load (USEPA 2004c).

 Compliance Schedules—Compliance schedules that are consistent with jurisdiction tributary strategies may be incorporated into permits, where such compliance schedules are needed, appropriate, and allowable unde r jurisdiction WQS and federal NPDES requirements (USEPA 2004d).

 Watershed permits/trading—Watershed permits , which may accommodate nitrogen and phosphorus trading, may be used if such an appr oach would ensure protection of applicable

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‐ 8 December 29, 2010Chesapeake Bay TMDL

jurisdiction WQS and would be consistent with existing EPA policy regarding trading (USEPA 2004d).

In 2005 the seven Bay jurisdictions began impl ementing the new permitting approach. As of June 2010, the permits for the significant nitrogen and phosphorus sources have been issued with nitrogen and phosphorus limits consistent with th e Tributary Strategy allo cations (described in Section 1.2.1) (some of which may include compliance schedules) to 64 percent of the significant wastewater treatment f acilities (305 out of the total 478) , accounting for 74 percent of the total design flow, 76 pe rcent of the total nitrog en loads and 91 percent of the total phosphorus loads from significant faci lities (Table 4-6).

By the end of 2011, EPA expects all 478 significant wastewater treatment facilities in the Bay watershed to have annual nitrogen and phosphorus lo ad limits in place in their permits (some of which may have compliance schedules as well).

Table 4-6. Nitrogen and phosphorus permit tracking summary under the Basinwide NPDES Wastewater Permitting Approach, through December 2010

Jurisdiction Significant facility NPDES Permits drafted Permits issued Design flow of facilities permits issued Percent of design flow for permits issued/significant facilities DC a 1 1 1 152.5 100%
DE 4 4 4 3.3 100%
MD 87 72 51 357.7 42%
NY 28 1 1 20.0 22%
PA 213 141 103 434.1 67%
VA 125 125 125 1,253.5 100%
WV b 20 16 16 27.737 100%

Total 478 364 305 2,259.7 74% Source: USEPA Region 3, Region 2, Facilit ies identified in the final Phase 1 WIPs Notes: Some industrial design flows are not available or not co mparable and not listed in the database. Some permits may contain compliance schedules. a. Blue Plains WWTP serves DC and parts of MD and VA, but is only counted once. b. Multiple facilities (4) share one NPDES permit in West Virginia.



### 4.5 REGULATED POINT SO URCE LOAD SUMMARIES This section presents load estimates for each major point source sector.



### 4.5.1 Municipal Wastewater Discharging Facilities A municipal wastewater facility is defined as a facility discha rging treated wastewater from municipal or quasi-municipal sewer systems. EPA identified 3,582 NPDES permitted facilities as discharging municipal wastewater into the Chesapeake Bay watershed. Table 4-7 provides a summary of municipal wastewater fa cilities by jurisdiction; a complete list is available in Appendix Q.

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‐ 9 December 29, 2010Chesapeake Bay TMDL

Table 4-8 and Table 4-9 summarize modeled 2009 municipal wastewater loading estimates by jurisdiction and ma jor river basi n, respectively, for total nitrogen and phosphorus loads delivered to the Chesapeake Bay. Modeled sediment loads fo r those facilities are not presented because wastewater discharging facilities represent a de minimis source of sediment (i.e., less than 0.5 percent of the 2009 total sediment load). In 2009 municipal wa stewater treatment facilities contributed an estimated 17 percen t of the total nitrog en and 16 percent of the total phosphorus loads delivered to Chesapeake Bay.

Table 4-7. Municipal wastewater facilities by jurisdiction

Jurisdiction Significant Nonsignificant DC 1 1 DE 3 1 MD 75 163 NY 26 26 PA 183 1246 VA 101 1618 WV 13 125 Total 402 3180 Source: EPA Region 3, EPA Region 2 Note: Blue Plains wastewater treatment plant serves DC and portions of Maryland and Virginia but is counted once in this table as a DC plant.

Table 4-8. Model estimated 2009 municipal wastewater loads by jurisdiction delivered to Chesapeake Bay

Jurisdiction Flow (mgd) Total nitrogen delivered (lb/yr) Total phosphorus delivered (lb/yr) DC 140 2,387,918 20,456 DE 2 42,529 4,984 MD 563 11,928,717 568,905 NY 62 1,360,684 159,096 PA 335 9,391,741 740,397 VA 585 16,926,806 1,047,998 WV 13 188,137 62,674 Total 1,698 42,226,535 2,604,509 Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Table 4-9. Model estimated 2009 municipal wastewater loads by major river basin delivered to Chesapeake Bay

Basin Flow (mgd) Total nitrogen delivered (lbs/yr) Total phosphorus delivered (lbs/yr) Susquehanna River 383 10,556,831 835,426 MD Eastern Shore 25 696,872 70,540 MD Western Shore 254 7,279,406 331,362 Patuxent River 58 640,507 61,948 Potomac River 635 9,475,644 412,464 Rappahannock River 23 376,453 46,463 York River 20 691,550 45,012 James River 299 12,494,335 798,615 VA Eastern Shore < 1 14,937 2,679 Total 1,698 42,226,535 2,604,509 Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

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‐ 10 December 29, 2010Chesapeake Bay TMDL

Figure 4-7 and Figure 4-8 illustrate the prevalence and locations of significant and nonsignificant municipal wastewater discharge faciliti es, respectively, across the watersh ed.

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-7. Significant wastewater treatment facilities in the Chesap eake Bay watershed.

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‐ 11 December 29, 2010Chesapeake Bay TMDL

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-8. Nonsignificant municipal wastewater tr eatment facilities in the Chesapeake Bay watershed.

Data related to municipal and industrial facilitie s are in the Bay Watershed Model point source database maintained by the CBP and include in formation for the 478 significant industrial, municipal, and federal facilities di scharging directly to the surface waters in the watershed. The wastewater data used to calibrate the Bay Waters hed Model cover the 1984 to 2005 time frame and are updated annually as data beco me available. Data are largely supplied by the seven watershed

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‐ 12 December 29, 2010Chesapeake Bay TMDL

jurisdictions but are also obtained from NP DES permit databases, including EPA’s Permit Compliance System (PCS) and juri sdiction discharge m onitoring reports (DMR s). For each facility outfall, the database includes monthly flow and mo nthly average concentrations for total nitrogen, ammonia, nitrate and nitrite, total organic nitr ogen, total phosphorus, orthophosphate, total organic phosphorus, total suspended solids, biological oxygen demand, and DO.

Because the Bay jurisdictions are required to submit monthly concentration and flow data to EPA for only significant dischargers, the Bay Wa tershed Model point s ource database does not include comprehensive information useful for characterizing the nonsig nificant facilities (especially nonsignificant industrials) for the Ba y TMDL. For nonsignificant municipal facilities, all Bay jurisdictions conducted a one-time da ta collection in 2008 fo r the nitrogen and phosphorus discharge data, and estimates are base d on any available data sources and default values recommended in Chesapeake Bay Watershed Model Application and Calculation of Nutrient and Sediment Loadings – Appendix F: Phase IV Chesapeake Bay Watershed Model Point Source Load (CBP 1998). EPA supplemented this in formation by querying the Integrated Compliance Information System database (ICIS) for jurisdictions that have migrated to ICIS as of 2009 (District of Columbia, Maryland, Penns ylvania, and New York), querying the PCS database for jurisdictions that have not yet mi grated to ICIS (Delaware, Virginia and West Virginia), and obtaining Maryland and Virginia facility information directly from Maryland Department of the Environment (MDE) and Virginia Department of Environmental Quality (VADEQ), respectively.

For more information regarding the data used to represent municipal wastewater discharge facilities and how they were incorporated into modeling for the TMDL, see Section 7 of the Bay Watershed Model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem =26169

Appendix Q provides facility-specific informati on including NPDES ID, location, and more for all wastewater dischargers accounted for in the Bay TMDL.



### 4.5.2 Industrial Discharge Facilities Industrial discharge facilities ar e facilities discharging process wa ter, cooling water, and other contaminated waters from industrial or co mmercial sources. EPA identified 1,679 NPDES permitted facilities discharging industrial wa stewaters in the Chesapeake Bay watershed ( Table 4-10 , Appendix Q), with 76 si gnificant facilities ( Figure 4-9 ) and 1,603 nonsignificant facilities ( Figure 4-10 ). In 2009 industrial wastewater dischargi ng facilities contribu ted an estimated 7.3 million pounds of the total n itrogen and 1.27 million pounds of the total phosphorus loads delivered to Chesapeake Bay ( Table 4-11 and Table 4-12 ) an estimated 3 percent and 8 percent, respectively, of all nitrog en and phosphorus loads delivered to the Chesapeake Bay.

Table 4-12 summarizes modeled wast ewater nitrogen and phosphorus loading estimates using 2009 loading conditions. Modeled sedime nt loads fo r industrial or commercial facilities are not presented because their wastewater discharges represent a de minimis source of sediment (i.e., less than 0.5 percent of th e 2009 total sediment load).

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‐ 13 December 29, 2010Chesapeake Bay TMDL

Table 4-10. Industrial wastewater facilities

Jurisdiction Significant Nonsignificant DC 0 9 DE 1 1 MD 12 477 NY 2 45 PA 30 409 VA 24 639 WV 7 23 Total 76 1,603 Source: USEPA Region 3, Region 2

Table 4-11. 2009 Load estimates of industrial facility discharges

Jurisdiction Flow (mgd) Total nitrogen delivered (lbs/yr) Total phosphorus delivered (lbs/yr) DC 13 183,490 20,433 DE < 1 95,438 71 MD 48 1,989,243 267,093 NY 7 126,897 19,971 PA 179 2,010,639 260,140 VA 160 2,883,828 649,266 WV 14 55,213 53,592 Total 422 7,344,748 1,270,566 Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Table 4-12. 2009 Flow, total nitrogen, and total phosphorus load estimates of industrial wastewater facility discharges by major river basin

Basin Flow (mgd) Total nitrogen delivered (lbs/yr) Total phosphorus delivered (lbs/yr) Susquehanna River 184 2,171,197 281,922
MD Eastern Shore 5 302,210 45,626
MD Western Shore 21 1,369,383 105,100
Patuxent River 3 50,615 38,689
Potomac River 71 779,885 420,997 Rappahannock River 5 78,006 36,039
York River 81 478,892 81,675
James River 51 1,979,297 259,331
VA Eastern Shore 1 135,211 1,160
Total 422 7,344,697 1,270,539 Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

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‐ 14 December 29, 2010Chesapeake Bay TMDL

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-9. Significant industrial wastewater disch arge facilities in the Chesapeake Bay watershed.

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‐ 15 December 29, 2010Chesapeake Bay TMDL

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario.

Figure 4-10. Nonsignificant industria l wastewater discharge facilities in the Chesapeake Bay watershed.

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‐ 16 December 29, 2010Chesapeake Bay TMDL

Discharge Monitoring Report (DMR) data from th e population of industrial facilities were used to derive loadings where available. The majo rity of nonsignificant i ndustrial facilities do not have DMR data for nitrogen and phosphorus. However, the default values from typical pollutant concentrations (Tetra Tech 1999) were used to estimate the loads where DMR data are not available, except for power plants and other facilities with high flows.

Industrial facilities, such as power plants, petroleum refineries, and steel mills, that were not on the significant facility list were considered as high-flow, nonsignifi cant faciliti es in the evaluation. Nitrogen and phosphorus loads resulting from the use of flue gas desulfurization units, effluent from coal ash ponds and biocide app lications at high-flow f acilities were estimated from available databases. Data sets queried in clude EPA’s PCS and ICIS permit systems, 316(b) cooling water intake structure re gulation data, U.S. Department of Energy’s Energy Information Administration data, and EPA’s eGrid database.

Thirty-two power plants were identified as be ing in the Chesapeake Bay watershed. Eight of those facilities use cooling towers as part of thei r cooling system. Of the 32 facilities, 18 use coal as a fuel source; 7 use a flue gas desulfuriz ation, and 13 use ash ponds. Eighty-nine other highflow industrial sites were identified in the watershed and represent a variety of industrial activities.

Pollutant loads were estimated for the eight faci lities that use cooling towers. The PCS and ICIS databases were queried for blowdown flows, and cooling tower chemical vendors were consulted to estimate water quality conditions in the towers . Facility use rates were then obtained from EPA’s eGrid database to charac terize utilization routines and variability in blowdown events. Similarly, flue gas desulfurization and ash pond lo ads were estimated using data obtained from the PCS and ICIS databases.



### 4.5.3 Combined Sewer Overflows Combined sewer systems (CSS) are sewers that are designed to coll ect rainwater runoff, domestic sewage, and industrial wastewater in the same pipe. Normally, the systems transport wastewater to a treatment plant, where it is tr eated and discharged to surface waters. However, during heavy rainfall or snowmelt, flow volumes in a CSS can exceed the capacity of the sewer system or treatment plant. To avoid situations where excess flows overwhelm the sewer network or the treatment capacity of the treatment system, CSSs are designe d to overflow during times of high volume, discharging untreated excess wastewater directly to nearby streams, rivers, or other waterbodies.

Such overflows, called combined sewer overflows (CSOs), contain stor mwater and untreated human and industrial waste, toxic materials, and debris. There are 64 CSO communities in the Chesapeake Bay watershed ( Table 4-13 and Figure 4-11 ).

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‐ 17 December 29, 2010Chesapeake Bay TMDL

Table 4-13. Combined sewer system communities in the Bay watershed

Jurisdiction River basin NPDES ID Facility name DC Potomac DC0021199 Washington, District of Columbia DE Eastern Shore DE0020265 S eaford Waste Treatment Plant MD Eastern Shore MD0020249 Federalsburg WWTP MD Eastern Shore MD0021571 City of Salisbury WWTP MD Potomac MD0021598 Cumberland WWTP MD Patapsco MD0021601 Patapsco WWTP MD Eastern Shore MD0021636 Cambridge WWTP MD Eastern Shore MD00 22764 Snow Hill Water & Sewer Department MD Potomac MD0067384 Westernport CSO MD Potomac MD0067407 Allegany County CSO MD Potomac MD0067423 Frostburg CSO MD Potomac MD0067547 Lavale Sanitary Commission CSO NY Susquehanna NY0023981 Johnson City (V) Overflows NY Susquehanna NY0024406 Binghamton (C) CSO NY Susquehanna NY0035742 Chemung Co Elmira SD STP PA Susquehanna PA0020940 Tunkhannock Boro Municipal Authority PA Susquehanna PA0021237 Newport Boro STP PA Susquehanna PA0021539 Williamsburg Municipal Authority PA Susquehanna PA0021571 Marysville Borough WWTP PA Susquehanna PA0021687 Wellsboro WWTP PA Susquehanna PA0021814 Mansfield Boro WWTP PA Susquehanna PA0022209 Bedford WWTP PA Susquehanna PA0023248 Berwick Area Joint Sewer Authority WWTP PA Susquehanna PA0023558 Ashland WWTP PA Susquehanna PA0023736 Tri-Boro Municipal Authority WWTP PA Susquehanna PA0024341 Canton Boro Auth. WWTP PA Susquehanna PA0024406 Mount Carmel WWTF PA Susquehanna PA0026107 Wyoming Valley Sanitary Authority WWTP PA Susquehanna PA0026191 Huntingdon Borough WWTP PA Susquehanna PA0026310 Clearfield Mun. Auth. WWTP PA Susquehanna PA0026361 Lower Lackawanna Valley Sanitary Authority WWTP PA Susquehanna PA0026492 Scranton Sewer Authority WWTP PA Susquehanna PA0026557 Sunbury City Municipal Authority WWTP PA Susquehanna PA0026743 Lancaster City WWTP PA Susquehanna PA0026921 Greater Hazelton Joint Sewer Authority WWTP PA Susquehanna PA0027014 Altoona City Auth. - Easterly WWTP PA Susquehanna PA0027022 Altoona City Auth. - Westerly WWTF PA Susquehanna PA0027049 Williamsport Sanitary Authority – West Plant PA Susquehanna PA0027057 Williamsport Sanitary Authority – Central Plant PA Susquehanna PA0027065 LRBSA - Archbald WWTP PA Susquehanna PA0027081 LRBSA - Clinton WWTP PA Susquehanna PA0027090 LRBSA - Throop WWTP PA Susquehanna PA0027197 Harrisburg Advanced WWTF PA Susquehanna PA0027324 Shamokin Coal Twp Joint Sewer Authority PA Susquehanna PA0028631 Mid-Cameron Authority

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‐ 18 December 29, 2010Chesapeake Bay TMDL

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‐ 19 December 29, 2010 Jurisdiction River basin NPDES ID Facility name PA Susquehanna PA0028673 Gallitzin Borough Sewer and Disposal Authority PA Susquehanna PA0036820 Galeton Borough Authority WWTP PA Susquehanna PA0037711 Everett Area WWTP PA Susquehanna PA0038920 Burnham Borough Authority WWTP PA Susquehanna PA0043273 Hollidaysburg STP PA Susquehanna PA0046159 Houtzdale Boro Municipal Sewer Authority PA Susquehanna PA0070041 Mahanoy City Sewer Authority WTP PA Susquehanna PA0070386 Shenandoah Municipal Sewer Authority WWTP PA Susquehanna PAG062202 Lackawanna River Basin Sewer Authority. PA Susquehanna PAG063501 Steelton Boro Authority VA James VA0063177 Richmond VA James VA0024970 Lynchburg VA James VA0025542 Covington Sewage Treatment Plant VA Potomac VA0087068 Alexandria WV Potomac WV0020150 City of Moorefield WV Potomac WV0021792 City of Petersburg WV Potomac WV0023167 City of Martinsburg WV Potomac WV0024392 City of Keyser WV Potomac WV0105279 City of Piedmont

CSOs are considered point sources and are assigned WLAs in this TMDL. EPA’s CSO Control Policy is the national framework for implemen ting controls on CSOs through the NPDES permitting program. The policy resulted from ne gotiations among EPA, m unicipal organizations, environmental groups, and state agencies. It prov ides guidance to municipalities and state and federal permitting authorities on how to meet the CWA’s pollution control goals as flexibly and cost-effectively as possible. Th e CSO policy was published in the Federal Register (FR) (59 FR 18688, April 19, 1994). CSO communities are require d to develop Long-Term Control Plans (LTCPs), detailing steps necessary to achieve full compliance with the CWA.

EPA relied on various sources of information to characterize the prevalence of CSOs in the Bay watershed and to quantify their loads for the Bay TMDL. There are 64 CSO communities in the Bay watershed (Table 4-13). Overflow volume a nd pollutant loading from CSO communities are heavily dependent on the service area or catchment area of the combined system. Service area data obtained from the communities were used to calculate the loading from each community during high-flow events. Precip itation data observations were also obtained from weather monitoring stations proximate to each community to derive runoff volumes. Estimates of overflows and associated pollutant loads from CSO communities were then developed using various sources of water quality data includ ing monitoring data a nd literature values.Chesapeake Bay TMDL

Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-11. CSO communities in the Chesapeake Bay watershed.

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For four of the largest CSO communities in the watershed—Alexandria, Virginia; Lynchburg, Virginia; Richmond, Virginia; and the District of Columbia—EPA relied heavily on readily available and relatively detailed LTCPs to characterize overflows. In addition, EPA ran simulations of existing sewer models for thos e communities to support developing overflow and water quality estimates. EPA used the District of Columbia’s CSS mode l to develop loading estimates for the CSOs. For the Alexandria, Richmond, and Lynchburg CSSs, various versions of EPA’s Storm Water Management Model (SW MM) were used to estimate overflows. CSO discharge monitoring data were available fo r the Alexandria and Richmond CSSs, but no samples were available from Lynchburg because the LTCP calls for complete separation of this system (i.e., separation of the stor m sewers from sanitary sewers).

Information related to loading from the othe r 60 CSO communities in the watershed includes spatial data collected as a resu lt of a direct survey of th e communities to support the TMDL, limited water quality and overflow data from some of the CSO communities in the watershed, and representative water quality c oncentrations available in the literature. For further information regarding the data used to estim ated CSO loads, see Section 7 of the Chesapeake Bay Watershed Model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem =26169

. To avoid the difficulty of measuring LTCP im plementation progress with weather-dominated CSO loading estimates, EPA used the 10-year average CSO loads for 1991–2000, which correlates with the hydrologic pe riod selected for the TMDL (s ee Section 6.1.1). The loads from that 10-year period were used as the baseline to assess CSO progress and WLAs. Any CSO implementation progress will be tracked and input in the model as a reduction factor to represent a reduction achieved from the baseline. Thus, a ny reduction will be from management actions only and not from climate variation. The CSS land use will be changed to urban area for stormwater simulation in the model if there is C SS separation in the implementation plan and the separation acreage is reported with the reduc tion factor for implemen tation progress tracking.



### 4.5.4 Sanitary Sewer Overflows Properly designed, operated, and maintained sanita ry sewer systems are meant to collect and transport all the sewage that flows into them to a WWTP. SSOs are illegal discharges of raw sewage from municipal sanitary sewer systems. Frequent SSOs are indicative of problems with a community’s collection system and can be due to multiple factors:

 Infiltration and inflow contribu tes to SSOs when rainfall or snowmelt infiltrates through the ground into leaky sanitary sewers or when excess water flows in through roof drains connected to sewers, broken pi pes, or badly connected sewer service lines. Poor service connections between sewer lines and building service lines can contribute as much as 60 percent of SSOs in some areas.

 Undersized systems contribute to SSOs when sewers and pumps are too small to carry sewage from newly developed su bdivisions or commercial areas.

 Pipe failures contribute to SSOs as a result of blocked, broken, or cracked pipe s; tree roots growing into the sewer; sections of pipe settl ing or shifting so that pipe joints no longer match; and sediment and other material build ing up causing pipes to break or collapse.

 Equipment failures contribute to SSOs because of pump failures or power failures.

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SSOs represent a source of nitrogen and phosphorus to the Chesapeake Bay; however, information available to characterize their cont ribution to the overall nitrogen and phosphorus loads delivered to the Bay is limited largely beca use of their illegality and infrequency. Although the Bay Watershed Model does not specifically account for SSOs, the nitrogen and phosphorus load contributions from SSOs are part of the background conditions incorporated into the Phase 5.3 watershed model and, therefore, such loads ar e accounted for in the data used for calibration of the Bay Watershed Model. Because SSOs are illegal, however, the Chesapeake Bay TMDL assumes full removal of SSOs a nd makes no allocation to them.



### 4.5.5 NPDES Permitted Stormwater Urban and suburban stormwater discharges co ntain nitrogen, phosphorus, and sediment from sources such as pet wastes, lawn fertilizers, construction activit y, impervious surfaces, and air contaminants. The in-stream bank and bed scouri ng caused by increased volumes and durations of stormwater discharges cont ribute additional sediment and n itrogen and phosphorus loads to the Bay and its tributaries. Those nitrogen, phos phorus, and sediment loads affect local water quality, habitats, and the Bay downstream and re present a significant proportion of nitrogen, phosphorus, and sediment loads to Bay. The CBP estimates that in 2009 stormwater from urban and suburban development contributed to 16 percen t of the sediment loadings, 15 percent of the phosphorus loadings, and 8 percent of the nitrogen loadings to the Bay (Bay Watershed Model 2009 Scenario).

Under the federal stormwater regulatory program, three broad categories of stormwater discharges are regulate d (see 40 CFR 122.26, CFR 122.30-37):

 Stormwater discharges from medium and la rge Municipal Separate Storm Sewer Systems (MS4s) and small MS4s in Census Bureau defined urbanized areas

 Stormwater discharges associated with construction activity 1 acre and larger

 Stormwater discharges associated with specified categories of industrial activity

In addition, EPA established a process for desi gnating and requiring NPDES permit coverage for additional stormwater discharges, im plementing section 402(p)(2)(E). This residual designation authority (RDA) of section 402(p)(2)(E) is in 40 CFR 122.26(a)(9)(i)(C) a nd (D). EPA retains additional authority in CWA section 402(p)(5) and (6) to designate additi onal point sources of
stormwater.
EPA’s intent in creating the MS4 Stormwater Pr ogram was to regulate st ormwater discharges by requiring the municipalities to de velop management programs to c ontrol stormwater discharging via the MS4, i.e., stormwater collected by the MS4 from throughout its service area.

CWA section 402(p) establishes th e framework for EPA to addre ss stormwater discharges. In Phase I, EPA established NPDES permit requirement s for stormwater discharges associated with

 Industrial activity, including c onstruction activity disturbing 5 acres or greater, including sites smaller than 5 acres if th ey are associated with a common plan of development or sale that is at least 5 acres in size

 Discharges from MS4s serving populations of 100,000 or more

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In Phase II, EPA established permit require ments for stormwater discharges from

 Construction activity disturbing 1 to 5 acres, including sites sma ller than 1 acre if they are associated with a common plan of development or sale that is at least 1 acre in size

 Small MS4s serving populations of fewer than 100,000 in urbanized areas

With respect to Phase II MS4s, EPA considers st ormwater discharges from within the geographic boundary of the urbanized area (and designated areas ) served by small MS4s to be regulated (64 FR 68722, 68751-52 and 68804, Appendix 2, December 8, 1999). The reason for regulating small MS4s in urbanized areas was based on the correlation between the degree of development/ urbanization and adverse water quality impacts fr om stormwater discharged from such areas.

EPA can and has designated additional stormwater discharges, such as those from impervious surfaces above a certain size threshold, using its residual designation authority under 40 CFR 122.26(a)(9)(i)(C) and (D). At the discretion of the NPDES permitting authority, stormwater dischargers that require NPDE S permits can either obtain individual permits or, with the exception of medium and large MS4s, obtain coverage under general permits (see 40 CFR 122.28). Also, EPA has additional authority in CWA section 402(p)(5) and (6) to designate additional point sources of stormwater.

Figure 4-12 shows the locations of Phase I a nd II MS4s in the Bay watershed.

Unless stormwater discharges a re identified in EPA’s Phase I or Phase II regulations or are designated pursuant to CWA section 402(p)(2)(E) or 402(p)(6), the discharges are not regulated under CWA section 402. As explained in EPA gui dance, “stormwater discharges that are regulated under Phase I or Phase II of the NP DES stormwater program are point sources that must be included in the WLA portion of a TMDL” (USEPA 2002). Appendix Q includes the stormwater permits subject to this Bay TMDL.

It is estimated that existing NPDES MS4 ar eas contributed approximately 7,027,362 lbs total nitrogen, 900,868 lbs total phosphorus, and 287,295 t ons of sediment annually in 2009. That compares to the total load delivered annua lly to the Bay of 251,040,081 lbs total nitrogen, 16,619,332 lbs total phosphorus and 4,000,118 tons sedi ment by all sources (Bay Watershed Model 2009 Scenario).

The contribution from industrial stormwater discharges subject to NPDES permits has been estimated on the basis of data submitted by juri sdictions in their Phase I WIPs, including the number of industrial stormwater permits per c ounty and the number of urban acres regulated by industrial stormwater permits. For the Bay TMDL , the permitted industrial stormwater load is subtracted from the MS4 load when applicable. Table 4-14 provides an accounting of the current individual and general stormwater NPDES permit s issued within the Chesapeake Bay watershed.

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Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario

Figure 4-12. Phase I and II MS4s in the Chesapeake Bay watershed.

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Table 4-14. NPDES stormwater permittees by jurisdiction and in the Chesapeake Bay watershed, summer 2009 NPDES Stormwater permit type

Jurisdiction MS4 Phase I MS4 Phase II Industrial Construction Total % Permittees in the Bay Baywide 1 0 60 212 273 1.6%
DC Districtwide 1 0 60 212 273 Baywide 1 0 48 NA* 49 0.3%
DE Statewide 14 3 337 1,375 1,729 Baywide 11 82 1,578 8,300 9,971 57.6%
MD Statewide 11 82 1,578 8,332 10,003 Baywide 0 34 122 470 626 3.6%
NY Statewide 1 502 1,393 7,251 9,147 Baywide 0 206 1,238 906 2,350 13.6%
PA Statewide 2 727 2,494 2,399 5,622 Baywide 11 75 975 2,252 3,313 19.2%
VA Statewide 11 90 1,432 2,851 4,384 Baywide 0 3 113 651 767 4.4%
WV Statewide 0 45 933 2,488 3,466 Bay 23 400 4,086 12,791 17,300 100% Total States 40 1,449 8,227 24,908 34,624 Source: Phase 5.3 Chesapeake Bay Watershed Model 2009 Scenario Note: Numbers of permittees are not static, and especially fo r categories like construction are fluctuating regularly. * Not including Delaware

Data used to characterize loads from regulated stormwater activities and to represent these sources in the model are available from th e jurisdictions’ NPDES programs and from EPA Region 3’s NPDES permitting, the permitting authorit y in the District of Columbia and for federal facilities in Delaware. Details relate d to how loads for MS4s and NPDES-permitted construction and industrial stormwater activities were derived for the Bay TMDL are in Section 7 of the Phase 5 Chesapeake Bay Watershed Model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem =26169

.



### 4.5.6 Concentrated Anim al Feeding Operations The NPDES program regulates the discharge of po llutants from point sources to waters of the United States. Concentrated Animal Feeding Oper ations (CAFOs) are included in the definition of point sources in CWA section 502(14). To be considered a CAFO, a facility must first be defined as an AFO.

AFOs are agricultural operations where animals are kept and raised in conf ined situations. AFOs generally congregate animals, f eed, manure, dead animals, and production operations on a small land area. Feed is brought to the animals rather than the animals grazing or otherwise seeking feed in pastures. Such operations are defined as AFOs if animals are confined for 45 or more

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days per year in facilities where vegetation a nd other growth are not present during the normal growing season [40 CFR 122.42(b)(1)].

AFOs that meet the regulatory definition of a CAFO or that are designated as a CAFO are regulated under the NPDES permitting program and are required to seek NPDES permit coverage if they discharge or propose to disc harge. The NPDES regulations define AFOs as CAFOs based primarily on the number of animals confined ( Table 4-15 ) (for example, a large dairy CAFO confines 700 or more dairy cattle) [4 0 CFR 122.23(b)(2), (4), and (6)]. An AFO that is not defined as a CAFO may be designated as a CAFO i f it meets certain conditions [40 CFR 122.23(c)].

Table 4-15. Federal numeric thresholds for small, medium, and large CAFOs
Size thresholds (number of animals) Animal sector Large CAFOs Medium CAFOs Small CAFOs Cattle or cow/calf pairs 1,000 or more 300–999 less than 300 Mature dairy cattle 700 or more 200–699 less than 200
Veal calves 1,000 or more 300–999 less than 300 Swine (weighing over 55 pounds) 2,500 or more 750–2,499 less than 750 Swine (weighing less than 55 pounds) 10,000 or more 3,000–9,999 less than 3,000
Horses 500 or more 150–499 less than 150 Sheep or lambs 10,000 or more 3,000–9,999 less than 3,000 Turkeys 55,000 or more 16,500–54,999 less than 16,500 Laying hens or broilers (liquid manure handling systems) 30,000 or more 9,000–29,999 less than 9,000

Chickens other than laying hens (other than a liquid manure handling systems) 125,000 or more 37,500–124,999 less than 37,500

Laying hens (other than a liquid manure handling systems) 82,000 or more 25,000–81,999 less than 25,000

Ducks (other than a liquid manure handling systems) 30,000 or more 10,000–29,999 less than 10,000

Ducks (liquid manure handling systems) 5,000 or more 1,500–4,999 less than 1,500 Source: 40 CFR 122.23(b)

Under federal regulations, NPDES permits for CA FOs require CAFOs to implement the terms of a site-specific nutrient management plan (NMP ) that includes a number of critical minimum elements [40 CFR 122.42(e)(1)]. Those requirements limit nitrog en and phosphorus loads from the production area as well as from the land appli cation area, where manure , litter and process wastewater must be applied in accordance with site -specific practices to ensure that nitrogen and phosphorus in the manure will be used appropriately. NPDES permits for all CAFOs must include technology-based effluent limits in accordance with 40 CFR 122.44. Permitted Large CAFOs that land-apply manure, litte r or process wastewater must comply with technology-based effluent limitations for land application per the effluent limitations guide lines (ELGs) at 40 CFR 412 (C) and (D). Unpermitted Large CAFOs may not have any discharges except for agricultural stormwater discharges from the land application area.

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Agricultural stormwater discharges are the pr ecipitation-related discha rges from CAFO land application areas where the CA FO land applies manure, litter or process wastewater in accordance with nutrient management practices “that ensure appropr iate agricultural utilization of the nutrients in the manure, litter or pr ocess wastewater” applied to the land—i.e., for permitted CAFOs, the terms of an NMP con cerning land application [40 CFR 122.23(e)(1)]. State technical standards are us ed in calculating the technology-based effluent limits in NPDES permits of Large CAFOs. Requirements for land application areas at small and medium CAFOs are based on the best professiona l judgment of the permit writer, and may also incorporate state technical standards. The agricultural stormw ater exemption does not apply to a CAFO’s production area. As a nonpoint source, an agricult ural stormwater discha rge is not subject to NPDES permitting requirements or water qualit y-based effluent limitations (WQBELs).

Any permit issued to a CAFO of any size must in clude a requirement to implement an NMP that contains, at a minimum, BMPs that meet the requirements specified in 40 CFR 122.42(e)(1). These include the following:

 Ensuring adequate storage of manure, litter, and process wa stewater, including procedures to ensure proper operation and main tenance of the storage facility.

 Managing mortalities to ensure that they are not disposed of in a liquid manure, stormwater, or process wastewater storage or treatment system that is not specifically designed to treat animal mortalities.

 Ensuring that clean water is diverted, as appropriate, from the production area.

 Preventing direct contact of confined an imals with waters of the United States.

 Ensuring that chemicals and other contaminants handled on-site are not disposed of in any manure, litter, process wastewater, or stormwater storage or treatment system unless specifically designed to treat such chemicals and other contaminants.

 Identifying appropriate site-spe cific conservation practices to control runoff of pollutants to waters of the United States.

 Identifying protocols for appropriate testing of manure, litter, process wastewater, and soil.

 Establishing protocols to land apply manure, litter, or process wastewater in accordance with site-specific nutrient management prac tices that ensure appropriate agricultural utilization of the nutrients in the ma nure, litter or process wastewater.

 Identifying specific records that will be ma intained to document the implementation and management of the minimum elements described above.

EPA and the jurisdictions have estimated the number of state or federal permitted CAFOs in the Chesapeake Bay watershed, in part, on the basis of the jurisdictions’ respective final Phase I WIPs ( Table 4-16 ).

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Table 4-16. Estimated number of state or federal permitted CAFOs

Jurisdiction # State or federal permitted CAFOs
Delaware a 165 Maryland a 365
New York 65 Pennsylvania 325 Virginia 30 West Virginia 30
Total 980

Sources: State data submitted to EPA for the Senate Environment and Public Works Committee Hearing on the Chesapeake Bay on April 20, 2009, and EPA Office of Wastewater Ma nagement’s latest NPDES CAFO Rule Implementation Status quarterly national CAFO number update. http://www.epa.gov/npdes/pubs/tracksum1Q10.pdf

. Note: a. The numbers of CAFOs in Maryland and Delaware with permits are estimated according to the number of Notices of Intent (NOIs) received as a result of the EPA Febr uary 2009 permit application deadline. The NOIs are being reviewed for permit requ irement completeness.



### 4.6 NONPOINT SOURCES

The term nonpoint source means any source of water pollution that does not meet the legal definition of point source (see Section 4.5). N onpoint source pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrologic modification. For purposes of the Chesapeake Bay TMDL anal ysis and modeling, nonpoint sources in the Chesapeake Bay watershed have been evaluated under the following categories:

 Agriculture (manure, bioso lids, chemical fertilizer)

 Atmospheric deposition

 Forest lands

 On-site wastewater trea tment systems (OSWTSs)

 Nonregulated stormwater runoff

 Oceanic inputs

 Streambank and tidal shoreline erosion

 Tidal resuspension

 Wildlife

For the Bay TMDL, Scenario Builder was used to provide the land use-ba sed scenario inputs to the Bay Watershed Model including forest lands , OSWTSs , nonregulated stormwater runoff, oceanic inputs, streambank and tidal shoreline erosion, tidal resuspension, and wildlife (see Section 5.7). Data sources for agriculture a nd atmospheric deposition in the Chesapeake Bay watershed are included in the re levant sections below. Scenario Builder provides estimates of nitrogen and phosphorus loads to the land and the area of soil available to be eroded. Loads are input to the Bay Watershed Model to generate m odeled estimates of loads delivered to the Bay. Additional information related to Scenario Builder and its application in Bay TMDL development (USEPA 2010d) is at http://archive.chesapeakeb ay.net/pubs/SB_V22_Final_12_31_2010.pdf

.

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### 4.6.1 Agriculture Agricultural lands account for 22 percent of the watershed, making agricultu re one of the largest land uses in the area, second only to forested and open wooded areas (69 percent). The Bay watershed has more than 87,000 farm operations and 6.5 million acres of cropland. However, the District of Columbia does not include any agricultural lands.

Farms in the Chesapeake Bay watershed produce mo re than 50 named commodities. The area’s primary crops are pasture, hay, corn, wheat, soybean s, vegetables, and fruits. The eastern part of the region is home to a rapidly ex panding nursery and greenhouse industry.

Animal operations account for more than 60 percen t of the region’s annual farm product sales. In the watershed, the six major types of animal ope rations are dairy cows, beef cattle, pigs, egg production, broilers, and turkeys. The three majo r animal production regions in the watershed, according to livestock concentration, are the lo wer Susquehanna River in Pennsylvania, the Shenandoah Valley in Virginia and West Virginia, and the Delmarva Peninsula in Delaware, Maryland, and Virginia. The Delmarva Peninsula is considered to be one of the country’s top poultry producing regions and, according to the 2002 Census, three Bay counties are among the top 20 poultry producing counties in the nation (for either poultry/eggs, br oilers, or layers): Sussex County, Delaware; Lancaster County, Pe nnsylvania; and Wicomico County, Maryland. In addition, at least one Bay county is among th e top 20 counties for production of the following farm commodities: turkey s; cattle and calves; milk and ot her cow dairy products; hogs and pigs; horses and ponies; corn for sila ge; snap beans; apples; short rotation woody crops; and nursery, greenhouse, floriculture, and sod.

Agriculture is the largest single source of nitr ogen, phosphorus, and sediment loading to the Bay through applying fertilizers, tilling croplands , and applying animal manure. Agricultural activities are responsible for approximately 44 percent of nitrogen and phosphorus loads delivered to the Bay and about 65 percent of sediment loads delivered to the Bay (Bay Watershed Model 2009 Scenario). Figure 4-13 compares modeled loads from agricultural lands for 1985 and 2009.

Data sources used to estimate nitrogen, phos phorus, and sedim ent from agriculture-related sources include information related to liv estock production and manure generation, crop production and nutrient management, fertilizer use and application, and implementation of BMPs. EPA in cooperation with the Chesapeake Bay Program’s Agricultural Nutrient and Sediment Reduction Workgroup and Modeling S ubcommittee relied on the many sources of information to characterize loads related to agri culture that are summarized in Section 2 of the Scenario Builder documentation Estimates of County-Level Nitrogen and Phosphorus Data for Use in Modeling Pollutant Reduction (USEPA 2010d)

. Examples of data sources are the U.S. Department of Agriculture (USDA) Agricultural Census; USDA, state, and university nutrient management standards and handbooks; peer-reviewe d journal articles; ag ricultural conservation data from state agricultural a nd environmental agencies; coun ty agencies, and nongovernmental organizations; and extensive input from members of the Chesapeake Bay Program’s Agricultural Nutrient and Sediment Reduction Workgroup.

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Source: Phase 5.3 Chesapeake Bay Watershed Model 1985 and 2009 Scenarios

Figure 4-13. 1985 and 2009 modeled tota l nitrogen, phosphorus, and sediment loads from agricultural lands across the Chesapeake Bay watershed.

Manure Animal populations vary across the Bay watershe d by animal type and management. Pastures exist in the watershed for dairy and beef heifers, goats, hogs, and in some places even chickens and turkeys. Animal feed BMPs are recognized by the Chesapeake Bay watershed model, and managing manure from production ar eas can include a suite of BM Ps for storage and handling. Land application of manure is an important nitrogen and phosphorus recycling process in agriculture. Because manure is so extensively used as a resource of nitrogen and phosphorus, it is considered as important as inor ganic fertilizer and is an impor tant source of nonpoint source pollution. Figure 4-14 and Figure 4-15 provide historical populat ion data of poultry and nonpoultry animals in the watershed, respectively.

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Annual manure production is calculated as a daily excreted amount per animal equivalent unit (1 animal equivalent unit equals 1,000 lbs live animal weight). Animal units are estimated for counties on the basis of USDA Agricultural Cens us data. The total amount of manure produced is then distributed among the applicable land us es, which include pasture, AFO, and other row crop land uses. The percentage of time an imals spend in pasture (based on state recommendations) is used to estimate the percen tage of total manure produced on pasture lands. For example, 50 percent pasture time equates to 50 percent of the total manure production occurring on pasture lands. Ma nure produced that is associated with time spent confined is considered to be generated on AFO acres. A fraction of that amount , (15–21 percent depending on animal type) is assumed to remain on th e AFO acres (i.e., not captured by storage and handling activities), while the re st is redistributed by land appl ication to pasture and row crop lands. The model simulates AFO acres si milarly to urban impervious areas.

Biosolids Applying biosolids, the nutrient-ri ch organic materials resulting from treating sewage sludge, as fertilizer to croplands represen ts another source of nutrients to the Bay. Biosolids typically contain plant nutrients (nitrog en, phosphorus, and potassium), although the amount of nutrients available from biosolids are normally lower than the amounts from most commercial fertilizers (Huddleston and Ronayne 1990). Nitrogen and phos phorus are the most prevalent nutrients found in sewage sludge.

Source: 2007 Agriculture Census

Figure 4-14. 2007 Chesap eake Bay watershed poultry populations by jurisdiction.

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Source: 2007 Agriculture Census
Figure 4-15. 2007 Chesapeake Bay watershed livestock populations by jurisdiction. Regulations governing use, dispos al and application of sewage sludge are in EPA’s Sewage Sludge Use or Disposal Regul ation (Part 503), which provides a framework for permitting sewage sludge use or disposal. No jurisdictions in EPA Region 3 have applied for program authorization of the federal Pa rt 503. Although all Bay jurisdictions have their own sewage sludge programs in place, only Virginia routin ely submits to EPA information regarding land application of biosolids. As a result, information available to characterize biosolids as a source and to represent it in the model is limited.

For model characterization, jurisd iction-specific data on biosolid s application were used. Land uses receiving biosolids include crops and pasture/hay, with diffe rent monthly proportions based on seasonal growing patterns. Modeled applica tion rates are the same as manure because biosolids are applied to land in the same fashion as manure.

For additional information relate d to representation of biosolids in the Bay TMDL, see the Phase 5.3 Chesapeake Bay Watershed Model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem =26169

Chemical Fertilizer Chemical fertilizer application practices ac ross the watershed can be estimated through commercial sales information. Fertil izer sales data are prepared by the Association of American Plant Food Control Officials on the basis of fertilizer consumption information submitted by state fertilizer control offices. The consumption data include total fertilizer sales or shipments for

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farm and non-farm use. Liming materials, peat , potting soils, soil amendments, soil additives, and soil conditioners are excluded. Materials used for the manufacture or blending of reported fertilizer grades or for use in other fertilizer s are excluded to avoid dupl icate reporting. A review of commercial fertilizer sales r ecords (from 1982 to 2007) showed that in all states, the sales are increasing. The increase can be attributed to both yield increases a nd increasing application. Removing the yield increases resulted in persiste nt increasing trends in chemical fertilizer nutrient application (except in Maryland where the trend is flat).

Model estimates of commercial fertilizer loads have been derived by back-calculating load from agricultural lands and de termining the proportion of nutrient species applied from commercial fertilizer, manure, and atmospheric deposition.

As phosphorus-based nutrient management plans in crease, the reliance on n itrogen fertilizer is expected to increase because less manure will be legally permitted to be applied to agricultural lands. Therefore chemical fertilizer s are and will remain a significant potential source of nitrogen and phosphorus to the Bay.



### 4.6.2 Atmospheric Deposition

Air sources contribute about one-t hird of the total nitrogen load s delivered to the Chesapeake Bay by depositing directly onto the tidal surf ace waters of Chesapeake Bay and onto the surrounding Bay watershed. Direct deposition to the Bay’s tidal surface waters is estimated to be 6 to 8 percent of the total (air and non-air) nitrogen load delivered to the Bay. The nitrogen deposited onto the land surface of the Bay’s wate rshed and subsequently transported to the Bay is estimated to account for 25 to 28 percent of th e total nitrogen loadings delivered to the Bay.

Atmospheric loads of nitrogen are from chemical species of oxidized nitrogen, also called NOx, and from reduced forms of nitrogen deposition, also called ammonia (NH 4 + ). Oxidized forms of nitrogen deposition originate from conditions of high heat and pressure and are formed from inert diatomic atmo spheric nitrogen (N 2 ). The principle sources of NOx are industrial-sized boilers such as electric power plants and th e internal combustion engines in cars, trucks, locomotives, airplanes, and the like.

Reduced nitrogen, or ammonia, is responsible for approximately one-third of the total nitrogen atmospheric emissions that eventually end up as loads to the Ba y. Ammonia sources are predominately agricultural, and ammonia is released into the air by volatilization of ammonia from manures and emissions from ammonia base d fertilizers. Minor so urces include mobile sources, slip ammonia released as a by-product of emission controls on NOx at power plants, and industrial processes.

Two types of atmospheric deposition—wet and dry—are input to the Bay Watershed and Bay Water Quality Models daily. Wet deposition occurs during precipitation ev ents and contributes to nitrogen loads only during days of rain or snow. Dry deposition occu rs continuously and is input at a constant rate daily in Bay Watershed and Bay Water Quality Models.

Because the Bay Watershed and Bay Water Quality Models are mass balance models, all sources of nitrogen and phosphorus inputs to the tidal Ba y must be accounted for. Given atmospheric deposition of phosphorus and organic forms of nu trients are minor inputs, the Bay Watershed

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and Bay Water Quality Models account for esti mated loads of phosphorus and organic nutrients to open surface waters only, on the assumption th at all phosphorus and organic nutrients are derived from aeolian or wind processes, which result in no net change in organic nitrogen on terrestrial or land surfaces but result in a net gain when depos ited directly on water surfaces.

Organic nitrogen is simulated only as wet deposit ion as dissolved organi c nitrogen because the magnitude of dry deposition of organic nitrogen is not well characterized in the literature. Therefore, the limited dry deposition of organic nitrogen simulated by the Bay Airshed Model is lumped into the oxidized nitrog en atmospheric dry deposition.

Atmospheric deposition monitoring in the Chesapeake watershed is through National Atmospheric Deposition Program (NADP) and AirMon stations throughout the watershed. Measured deposition at these discre te stations is used to extrapol ate to all the land and waters of the Chesapeake watershed through a wet deposit ion regression model developed by Grimm and Lynch (2000, 2005; Lynch and Grimm 2003). Dry de position data are estimated through the Community Multiscale Air Quality Model (CMAQ) (Dennis et al. 2007; Hameedi et al. 2007) (for more details, see Section 5.4).

Chesapeake Bay Airshed The Bay’s NOx airshed—the area where emission sources that contribute the most airborne nitrates to the Bay originate—is about 570,000 square miles, or ni ne times the size of the Bay’s watershed ( Figure 4-16 ). Close to 50 percent of the nitr ate deposition to the Bay is from air emission sources in Bay watershed jurisdicti ons. Another 25 percent of the atmospheric deposition load to the C hesapeake watershed is from the remaining area in the airshed. The remaining 25 percent of deposition is from the area outside the Bay airshed. The ammonia airshed is similar to the NOx airshed, but slightly smaller.

Source: Dr. Robin Dennis, EPA/ORD/NERL/AMAD/AEIB
Figure 4-16. Principle area of NO X emissions (outlined in blue) that contribute nitrogen deposition to the Chesapeake Bay and its watershed (solid blue fill) (the Bay airshed).

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‐ 35 December 29, 2010 Atmospheric Deposition Emissions Sources and Trends Between 1985 and 2005, the simulation period of the Bay Watershed Model, atmospheric deposition loads of nitrate (NOx) in the Ches apeake watershed have decreased by about 30 percent ( Figure 4-17 ). Considerable variability exists across the watershed, however, with the greatest reductions occurring in the northern and western portions (Grimm and Lynch 2000, 2005; Lynch and Grimm 2003). Figure 4-17 shows th e trend of estimated average nitrate and ammonia deposition concentrations in the Phas e 5 Model from 1984 to 2005. The average annual concentration from 1984 to 2005 was used as an adjustme nt to smooth out the high- and lowrainfall years, which bring different amounts of deposition load to the watershed depending on the volume of precipitation. Much of the reduc tion has been from point source air emission reductions, particularly from electric generatin g units (EGUs) such as electric power plants. Reductions from mobile sources, such as cars an d trucks, are another la rge contributor to the downward trend.

Annual Concentrations in Atdep

y = -0.0007x + 1.5153
R 2 = 0.1076 y = -0.0053x + 11.012
R 2 = 0.5791

y = -0.0046x + 9.4962
R 2 = 0.6469

y = -0.0202x + 40.649
R 2 = 0.8628 y = -0.0281x + 56.761
R 2 = 0.8372

y = -0.008x + 16.112
R 2 = 0.7207

0 0.1 0.2 0.3 0.4 0.5 0.6

1980 1985 1990 1995 2000 2005 2010

Yearmg/l NH3
NO3
DIN
NH3
NO3
DIN Linear (NH3) Linear (DIN) Linear (NO3) Linear (DIN) Linear (NO3) Linear (NH3)

Source: Phase 5.3 Chesa peake Bay Watershed Model.

Figure 4-17. Trend of estimated average nitrate and a mmonia deposition concentrations in the Phase 5 Model domain from 1984 to 2005.

Table 4-17 shows the estimated portion of deposited NOx loads on the Chesapeake watershed from four sectors including E GUs, mobile sources, industry, a nd all other sources. From 1990 to 2020, considerable reductions have been made in the power sector. In addition, both on road and off-road m obile sources have ongoing fleet turn over and replacement, wh ich is putting cleaner spark and diesel engines in service, and that is expected to continue beyond 2030. Table 4-17Chesapeake Bay TMDL

shows that in 1990, EGUs are the dominant sour ce of NOx; in 2020, mobile sources will be the dominant sources of NOx with EGUs the least contributo r of NOx. However Figure 4-17 shows that all sources will be decreasing th eir NOx em issions, and the total de position load in 2020 will be less than the 1990 load.

Average ammonia loads over the Phase 5 Chesapeake Bay Watershed Model domain have followed the trend in overall manure loads in th e watershed and have remained steady over the 1985 to 2000 simulation period ( Figure 4-17 ). Ammonia deposition is very site-specific and strongly influenced by local emissi ons. Local and regional trends in manure, such as the rise of poultry anim al units in the Eastern Shore and Sh enandoah basins and reduction of dairy farms in the northern portions of the watershed in the late 1980s, affect regional ammonia deposition in the Chesapeake watershed.

Table 4-17. Estimated portion of deposited NOx loads on the Chesapeake watershed from four source sectors—EGUs, mobile sources, industry, and all other sources in 1990 and 2020

Source sector 1990 2020 Power plants (EGUs) 40% 17% Mobile sources (on-road) 30% 32% Industry 8% 20% Other (off-road-construction; re sidential, commercial) 21% 31%
Source: Dr. Robin Dennis, EPA/ORD/NERL/AMAD/AEIB



### 4.6.3 Forest Lands Forested areas represent a signi ficant portion of the Chesapeake Bay watershed (see Figure 2-3), as approximately 70 percent of the watershed is composed of forested and open wooded areas. This land use contributes the lowest loading rate per acre of all the land uses, however. Compared with other major pollutant source sect ors in 2009, forest lands in the Bay watershed contributed an estimated 20 percent (49 million pounds per year) of total nitrogen, 15 percent (2.4 million pounds per year) of total phosphorus, and 18 percent (730,000 tons per year) of sediment of the total delivered loads to the Bay from th e watershed (Bay Watershed Model 2009 Scenario).

Forest land differs from most land uses in that a significant portion of the loads that come off the land do not originate in the forest s. Most of the nitrogen loads come from atmospheric deposition of nitrogen (Campbell 1982; Langland et al. 1995; Ritter and Chirnside 1984; Stevenson et al. 1987; Nixon 1997; Castro et al. 1997; Goodale et al. 2002; Pan et al. 2005 ; Aber et al. 1989; 2003; Stoddard 1994). Sediment and phosphorus load s originate from poorly managed forest harvesting with unprotected stream crossings an d unhealthy forest biota (Riekerk et al. 1988; Clark et al. 2000).

The Bay Watershed Model differentiates between harvested and un-harvested forest lands as distinct land uses. Un-harvested forest la nds contributed 1.63 lbs of nitrogen, 0.08 lb of phosphorus, and 0.02 ton of sediment per acre, which is the lowest loading rate of any land use. In contrast, harvested forest contributes 10.30 lbs of nitrogen, 0.47 lb of phosphorus, and 0.19 ton of sediment per acre. The loads from harveste d forest can be greatly reduced by using forest

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harvesting BMPs. The loads are estimated thr ough model calibration, which estimates loading rate per area on the basis of mon itoring stations in forested areas.

For additional information related to the repres entation of forest lands, see the Bay Watershed Model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem =26169

.



### 4.6.4 On-site Wastewater Treatment Systems Onsite Wastewater Treatment Systems (OSWTS), co mmonly referred to as septic systems, have the potential to deliver nitrogen and phosphorus to surface waters directly because of system failure and malfunction and indirectly through groundwater. Septic systems treat human waste using a collection system that discharges liquid wa ste into the soil through a series of distribution lines that compose the drain field. In properly functioning (n ormal) systems, phosphates are adsorbed, or gathered onto the soil surface, and retained by the soil as the effluent percolates through the soil to the shallow, groundwater table. Therefor e, functioning systems do not contribute nitrogen and phosphorus loads to surfa ce waters directly. A septic system failure occurs when there is a discharge of waste to the soil surface where it is available for washoff. As a result, failing septic systems can contribute high nitrogen and phosphorus loads to surface waters. Short-circuited systems (those close to st reams) and direct discharges to streams also contribute significant nitroge n and phosphorus loads.

OSWTSs represented an estimated 6 percent of the total nitrogen load from the Chesapeake watershed in 2009 (Bay Watershed Model 2009 Scen ario). Information on the watershed loads from OSWTSs is generally sparse . Detailed descriptions of data procedures, source information, and assumptions used in estimating t hose loads are in Palace et al. (1998).

For the Chesapeake Bay Watershed Model, the nu mber of OSWTSs in each modeling segment was estimated by calculating the number of house holds outside areas served by public sewer. One septic system was assumed to exist for ea ch household. Digital maps of 2009 sewer service areas were provided by 257 of the 403 major wast ewater treatment plants in the watershed contacted during a 2009 survey s ponsored by EPA. Digital data were also provided by the Maryland Department of Planning for all of Maryland, Fairfax County, and the Washington Council of Governments. In 2008 the CBP Office contacted some local jurisdictions and collected sewer service area data for all three Delaware counties, Albemarle, Arlington, Henrico, Loudoun, and Rockingham counties in Virginia and for James City, Newport News City, Virginia Beach, and Richmond in Virginia. Da ta were also collected for Perry, Dauphin, Lancaster, Lycoming, and Cumberland counties in Pennsylvania, and fo r Broome County in New York. For those major wastewater treatment pl ants that did not provide data and were not included in data supplied by county or state agencies, the extent of their sewer service area was estimated on the basis of population density.

EPA simulated the extent of existing sewer service areas using a thresholded and logtransformed raster data set of year 2000 popul ation density. A populati on density raster was created using a dasymetric mapping technique with 2000 Census Block Group data and a secondary road density raster map (Claggett an d Bisland 2004). A loga rithmic transformation was used to normalize the population density data in the surface raster. The standard deviations in the data range were examined to find the optimal threshold for re presenting sewer service

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areas in Maryland because statewide maps of ex isting sewer service areas were provided by the Maryland Department of Planning. A threshold of 1.5 standard deviations from the mean (> – 0.4177) was chosen and used to reclassify the surf ace raster into a binary grid. A low-pass filter (ignoring no data) was then us ed to smooth the data, and th e output was converted from a floating point to an integer grid. The resulting integer grid was us ed to represent potential sewer service areas for wastewater trea tment plants that did not submit digital data. Households in the Bay watershed were mapped using a similar dasymetric mapping technique and 2000 Census household data. The resulting raster data set of households was overlaid on the sewer service area map to estimate the number of households outs ide sewer service areas. The data were scaled from the year 2000 to the year 2009 using publis hed annual county-level population estimates adjusted for changes in average household size. In addition, the data were scaled back through time using county-level population estimates and spatially distributed raster data sets representing 1990 and 2000 Census Block Group data on the total number of households.

Using that methodology, the number of OSWTSs is estimated and the nitr ate loads exported to the river from OSWTSs are simulated. Phosphorus loads are assumed to be entirely attenuated by the OSWTSs. Standard engineering assumptions of per capita nitrogen waste and standard attenuation of nitrogen in the se ptic systems are applied. Overall, the assumption of a load of 4.0 kg/person-year is used at the edge of the OSWTS field, all in th e form of nitrate.

Using an average water flow of 75 gallons/person-day for a sep tic tank (Salvato 1982), a mean value of 3,940 grams of nitrogen /person-year for groundwater se ptic flow, 4,240 grams/personyear for surface flow of septic effluent, a nd typical surface/subsurface splits as reported by Maizel et al. (1995), a total nitr ogen concentration of about 39 mg /L at the edge of the septic field was calculated. This concentration compares favorably with Salvato (1982) who calculated OSWTS total nitrogen concentrations of 36 mg/L. It is assumed that attenuation of the nitrate loads between the septic system field and the ed ge-of-river nitrate loads represented in the Bay Watershed Model is due to: (1) attenuation in an aerobic saturated soils with sufficient organic carbon (Robertson et al. 1991; R obertson and Cherry 1992); (2) attenuation by plant uptake (Brown and Thomas 1978); or (3) attenuation in low-order streams before the simulated river reach. Overall, the total attenua tion is assumed to be 60 percen t (Palace et al. 1998) that is applied to all OSWTS in the Bay watershed exce pt for MD where the zone specific attenuation rates developed by MDE were used. MDE assumes an 80 percent delivery rate (or 20 percent attenuation) in critical areas; a 50 percent delivery rate within 1,000 feet from any perennial surface water; and a 30 percent delivery rate fr om distances greater than 1,000 feet from any perennial surface water ( http://www.mde.state.md.us/assets/d ocument/NutrientCap_Trading_Policy.pdf ).

Additional information related to how the number of OSWTSs is estimated and how they are represented in the model is available in the Bay Watershed Model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem =26169



### 4.6.5 Nonregulated Stormwater Runoff The sources of nitrogen, phosphorus and sediment from nonregulat ed stormwater are generally the same as those from regulated stormwater . Sources include residential and commercial application of fertilizer, land disturbance and po orly vegetated surfaces, atmospheric deposition

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‐ 38 December 29, 2010Chesapeake Bay TMDL

of nutrients, pet wastes, and de veloped properties. Together wi th regulated stormwater, the nitrogen, phosphorus, and sediment loads affect lo cal water quality and habitats and represent a significant proportion of nitrogen, phosphorus, and sediment loads to the Bay. The CBP estimates that, in 2009, urban and suburban devel opment and runoff contributed to 16 percent of the sediment loadings, 15 percent of the phos phorus loadings, and 8 percent of the nitrogen loadings to the Bay (Bay Wa tershed Model 2009 Scenario).

The regulated sources of stormwat er are discussed in the point sources section above (4.5.5). For the purposes of the TMDL, urban and suburban runoff occurring outside the NPDES regulatory purview is considered nonpoint s ource loading and is a component of the LA. However, note that CWA section 402(p) provides the au thority to regulate many of t hose discharges. If any of the discharges are designated for regulation, they wo uld then be considered part of the WLA. As discussed in Section 8 some of the unregulated so urces of stormwater are being shifted from the LA portion to the WLA portion of the TMDL as pot ential regulated source s to further increase the reasonable assurance that the TMDL reductions will be achieved. Some jurisdictions might have state stormwater regulatory programs and, therefore, could have little to no nonregulated
stormwater sources.
For additional details related to how the non-regu lated stormwater runoff loads were estimated in the Bay Watershed Model, see Section 7 in the Bay Watershed Model documentation at http://www.chesapeakebay.net/model_phase5.aspx?menuitem =26169

.



### 4.6.6 Oceanic Inputs The Chesapeake Bay is an estuary and, by defini tion, a mixture of fresh and salt water. The relative proportion of ocean water in any regi on of the Bay can be roughly estimated by its salinity because salt is a perfectly conservative tracer. The salinity of full strength seawater just outside the Chesapeake Bay mout h is about 35 parts per thousa nd (ppt). At mid-Bay around the where Potomac River enters the mainstem Bay, the salinity drops to about 15 ppt, or a mixture of about half seawater (43 percen t) and at the Bay Bridge betw een Annapolis and Kent Island, Maryland, salinity drops to about 6 ppt or 20 pe rcent seawater. While nitrogen, phosphorus and sediment concentrations are relatively low in oc ean water, the large volume of seawater entering the Bay brings considerable nitrogen, phosphorus, and sediment loads to the Bay.

Ocean input loads of nitrogen, phosphorus, and sedi ment to the Chesapeake Bay are determined by calibration to the three Bay water quality moni toring stations at the mouth of the Chesapeake Bay by using the Curvilinear-grid Hydrodynamic Three-Dimensional model (CH3D Hydrodynamic Model), which has a model grid a nd domain that extends about 10 km beyond the mouth of the Bay. Ocean boundary concentrations are set monthly in the Chesapeake Bay Water Quality and Sediment Transport Model (Bay Wa ter Quality Model) to best represent the nitrogen, phosphorus, and total susp ended solids concentrations of the monitoring stations at the Chesapeake Bay month on an incoming tide.

A previous study of ocean boundary loads found thatwhen accounting for all input loads to the Chesapeake Bay, including atmosphe ric deposition to tid al waters and ocean inputs, the ocean inputs were significant and accounted for about one-t hird of the total nitrogen and about half the total phosphorus loads to the Bay (Thomann et al. 1994). Ocean sediment inputs are

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predominantly sand and have little influen ce on light attenuation beyond the Bay mouth and lower mainstem Bay.

Several nutrient budgets of the ocean waters off the Chesapeake, also called the Middle Atlantic Bight, have been made (Fennel et al. 2006; Howarth et al. 19 95; Howarth 1998). Howarth (1998) estimates that for the northeast coast of the Un ited States, which include s the discharge of all watersheds from Maine to Virginia draining to th e Atlantic, the watershed inputs of nitrogen to coastal waters are 0.27 teragram (10 12 grams) from rivers and estuaries. Estimated inputs from direct atmospheric deposition to coastal waters are 0.21 teragram, and inputs from deep ocean upwelling are 1.54 teragrams for a total input to the coastal ocean of 2.02 teragrams.

The direct atmospheric deposition loads are roug hly equivalent to the watershed loads in the northeast United States. The estimated distribution of 2001 atmospheric deposition loads to North America and adjacent coastal ocean is shown in Figure 4-18 . Using the Community Multiscale Air Quality (CMAQ) Model estimates of at mospheric deposition lo ads to the coastal ocean under different air scenarios provides a means of adjusting the ocean boundary loads to changes in atmospheric deposition. Appendix L describes how the ocean boundary loads were adjusted to reflect projected changes in nitr ogen atmospheric deposition to th e coastal ocean and, therefore, coastal ocean nitrogen loads delivered to Chesapeake Bay.

Source: Dr. Robin Dennis, EPA/ORD/NERL/AMAD/AEIB

Figure 4-18. Estimated 2001 annual to tal deposition of nitroge n (kg/ha) to North America and adjacent coastal

ocean.

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### 4.6.7 Streambank and Tidal Shoreline Erosion

Steambank Erosion Streambank erosion is erosion from the reworking of streams and rivers, either as flow rates change as in the case of increased impervi ousness in a watershed (Center for Watershed Protection 2003), because of long-term changes in the landscape (Wa lter and Merritts 2008; Trimble 1999), or as a natural process of ri ver channel dynamics (Leopold et al. 1995).

In the Chesapeake Bay watershed, the relative am ounts of streambank erosion and erosion from the land is difficult to quantify (Gellis et al. 2009 ) because the water quality monitoring stations measure the total suspended sediment in the free -flowing rivers, which is composed of sediment from both sources. The Bay Watershed Model has estimates of land erosion derived from RUSLE estimates made in the National Resource Inventory ( http://www.nrcs.usda.gov/technical/NRI/ ), which could be used to quantify that source of sediment relative to the scour and erosion simulated in the rivers, but both sources of information are thought to be too crude to es timate the splits in erosion load s on a segment basis. However, on a watershed-wide basis, both sources of inform ation estimate that 70 percent of the sediment delivered to the Bay comes from erosion from land and 30 percent comes from bank erosion. That is consistent with other estimates from rese arch and field studies that find a wide variance of the portions of delivered erosion from land surf aces and bank erosion but could be generalized to about one-third of the erosi on as coming from bank erosion ( Figure 4-19 ).

23 0 77 0 0

31 0 17 29 23

9 32 46 13 0

0 10 20 30 40 50 60 70 80 90 100 Banks Ditch bed Crop Forest Construction

Percent 

## Sources of Erosion

Pocomoke River Mattawoman Creek L. Conestoga Creek

Source: Gellis et al. 2009

Figure 4-19. Relative estimates of sources of erosion from land sources (crop, forest, or construction) or bank sources banks and ditch beds).

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Because sediment monitoring statio ns in the watershed collect a ll the sediment loads passing the station, including both land erosi on and bank erosion sources, the stream bank load is accounted for, ultimately, both in the Chesapeake Bay watershed monitoring network and in the Bay Watershed Model, at least as part of the total combination of sediment from land and riverine sources. In the same way, streambank loads are also accounted for in tracking sediment load reductions from stream restora tion actions and through reductions of nitrogen, phosphorus, and sediment tracked in th e jurisdictions’ WIPs.

Tidal Shoreline Erosion
Tidal shoreline erosion is a combination of the erosion of fastland (or shoreline) and nearshore erosion. Figure 4-20 illustrates the tidal shoreline erosion process. Fastland and nearshore is subtidal and usually unseen. Subtidal erosion can be accelerated when shoreline pro tection activities such as stone revetment, a facing of st one placed on a bank or bluff to protect a slope, are used. That practice typically cuts off fastland erosion, bu t the reflected wave energy continues subtidal erosion until the wave energy no longer scours the bottom to the depth of a
meter or more.

Source: CBP Sediment Workgroup

Figure 4-20. Sources of total suspended solids in the Chesapeake including the two components of shoreline erosions, fastland and nearshore erosion.
Estimates of shoreline erosion were provided for the Bay Water Quality Model. Estimates of the shore recession rate, the elevation of the fastland, and the subtidal erosion rate were used to develop the shoreline erosion estimates. Figure 4-21 demonstrates considerable variation in the sediment load delivered by sedime nt erosion from segment to segment.



### 4.6.8 Tidal Resuspension The bottom of the Chesapeake Bay is covered by sedi ment that has been either carried into the estuary by rivers draining the Bay’s extensiv e watershed; eroded from the Bay’s lengthy shoreline; transported up-estuary from the A tlantic Ocean, through th e mouth of the Bay; introduced from the atmosphere; or generate d by primary productivity (Langland and Cronin 2003). Tidal resuspension is generated by episodic wave or current energy that scours the bottom sediment and resuspends the surficial sediment layers.

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Source: Chesapeake Bay Water Qualit y and Sediment Transport Model.
Figure 4-21. Estimated tidal sediment inputs for 1990 from the Chesapeake Bay watershed and from shore erosion. Shoreline sediment inputs (here labeled bank load) are estimated to be about equal to watershed inputs (here labeled as nonpoint source).

In the Bay Water Quality Model, a wave resuspen sion model simulates such episodic events. In some regions of the Bay, resuspended sediment can be one of the most detrimental sediment loads to SAV restoration as shown in results of sediment scoping scenarios run on the Bay Water Quality Model (Table 4-18). The Bay Water Quality Model was run to compare the base scenario of the 2010 Tributary Strategy against model scenarios that individually eliminated watershed loads of total suspended sediment, fa ll line loads of total su spended sediment, shore erosion loads, sediment resuspension loads, and ocean sediment loads. The model scenarios were run to determine which sediment source was mo st important. In most of the mainstem Bay, sediment resuspension loads were relatively more detrimental to SAV growth than were other sediment sources.



### 4.6.9 Wildlife Wildlife sources are rarely, if ever, consider ed in nitrogen and phosphorus TMDLs because wildlife only cycle nitrogen and phosphorus that alre ady exist in the system. To the extent that wildlife increases the av ailability of nitrogen and phosphorus for runoff, wildlife nitrogen and phosphorus loads are inherently represented in land use sources. As a specific example, the loads

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‐ 44 December 29, 2010 Table 4-18. Chesapeake Bay Water Quality and Sediment Transport Model -simulated SAV acres under a range of sediment scoping scenarios compared with the 2010 Tributary Strategy scenario

CBSEG SAV

acre No watershed loads % increase over base SAV

acre No fall line loads % increase over base SAV

acre No shore erosion loads % increase

over base SAV

acre No resuspension loads % increase over base SAV

acres No ocean sed loads % increase

over base CB1TF 11,253 23% 11,001 20% 9,751 6% 10,344 13% 9,173 0% CB2OH 212 63% 192 47% 177 36% 269 107% 138 6% CB3MH 609 44% 539 28% 478 13% 704 67% 450 7% CB4MH 1,150 30% 1,039 18% 1,096 24% 1,671 89% 980 11% CB5MH 9,432 9% 9,086 5% 10,34 1 20% 14,055 63% 9,177 6% CB6PH 825 21% 695 2% 701 3% 980 44% 728 7% CB7PH 14,236 4% 13,798 1% 13,959 2% 14,582 7% 14,162 4% CB8PH 6 25% 5 17% 5 5% 6 29% 5 18% a. The percentages are the percentage increa se in simulated SAV acres over the 2010 Tributary Strategy scenario SAV acres.

from the wooded land incorporate nitrogen a nd phosphorus loads that are cycled through wildlife. The overall loads from the watershed a nd each land use type are calibrated to observed data and literature load estimates, which also incl ude loads cycled through wildlife. As a result, no explicit allocation to wildlife is nece ssary or appropriate in the Bay TMDL.



### 4.6.10 Natural Background The Bay Airshed Model, Watershed Model, and Bay Water Quality Model all include the loads from natural background conditions because all th e Bay models are mass balance models and are calibrated to observed conditions. For example, the atmospheric deposition loads are monitored principally at the NADP sites. The deposition measured at those sites includes NOx from natural sources, which includes lightning, fo rest fires, and bacterial proce sses such as nitrification, which oxidizes ammonia (NH 3 ) to NO 2 or NO 3 . Those sources compose about 1 percent of the NOx deposition in the Chesapeake region (USEPA 2 010i). Natural background sources of ammonia are easily volatilized from land and water surfaces and are generated from the decay (ammonification) of natural sources of organic nitrogen. Those are likewis e a relatively small portion, relative to anthropogenic so urces, of the atmospheric loads estimated by the NADP sites.

Natural loads of nitrogen, phosphorus, and sediment from forested land are also part of the monitored load at the free-flowing stream, rive r, and river input mon itoring stations throughout the Chesapeake Bay watershed. Because the load s are part of the total loads to which the Chesapeake Bay Program’s mass balance mode ls are calibrated, the natural nitrogen, phosphorus, and sediment loads in the system, while small, are fully accounted for in the Bay TMDL assessment.

The natural background loads can be st be estimated by simulating th e All Forest scenario, which includes no point source, manure, or fertilizer loads. Atmospheric deposition loads in that scenario are set at estimated pristine levels. Th e scenario yields deliver ed nitrogen, phosphorus, and sediment loads that are more than an orde r of magnitude less than current conditions (see Appendix J).