Chesapeake Bay TMDL Tracker

The Chesapeake Bay Total Maximum Daily Load (Bay TMDL) sets limits on the amount of nitrogen, phosphorus and sediment pollution that can enter the Bay if it is to achieve applicable water quality standards. These pollution limits are further divided by jurisdiction and major river basin, and are based on state-of-the-art modeling tools, extensive monitoring data, peer-reviewed science and close interaction with jurisdictional partners.

The Chesapeake Bay TMDL Tracking and Accounting System (BayTAS) was developed to inform the EPA, watershed jurisdictions and the public on progress in implementing the Bay TMDL. BayTAS data are displayed through the TMDL Tracker. The TMDL Tracker displays the Bay TMDL allocations and tracks implementation progress (based on the Watershed Model Phase 5.3.2 and the jurisdictions' Phase II Watershed Implementation Plans (WIPs)). Learn more about the terminology of the Bay TMDL in the glossary found in Section 13 of the TMDL. Get answers to frequently asked questions about the Bay TMDL.

You can also track our progress toward the Bay TMDL and two-year milestones on ChesapeakeProgress.

Why measure progress based on Phase II WIP Planning Targets?

In December 2010, the Environmental Protection Agency established a pollution diet for the Chesapeake Bay, formally known as a Total Maximum Daily Load or TMDL.  The TMDL is designed to ensure that all nitrogen, phosphorus, and sediment pollution control efforts needed to fully restore the Bay and its tidal rivers are in place by 2025, with controls, practices, and actions in place by 2017 that would achieve at least 60% of the reductions from 2009 necessary to meet the TMDL.  The TMDL sets pollution limits (allocations) necessary to meet applicable water quality standards in the Bay and its tidal rivers.

As a result of this new Bay-wide “pollution diet,” Bay Program partners are implementing and refining Watershed Implementation Plans (WIPs) and improving the accounting of their efforts to reduce nitrogen, phosphorus, and sediment pollution. The WIPs developed by Delaware, the District of Columbia, Maryland, New York, Pennsylvania, Virginia, and West Virginia identify how the Bay jurisdictions are putting measures in place by 2025 that are needed to restore the Bay, and by 2017 to achieve at least 60 percent of the necessary nitrogen, phosphorus, and sediment reductions compared to 2009. Much of this work already is being implemented by the jurisdictions consistent with their Phase I WIP commitments, building on 30 years of Bay restoration efforts.

For their Phase II WIPs, EPA asked jurisdictions to make key stakeholders — local governments, conservation districts, farmers, builders and others — aware of their roles in cleaning up the region's waterways, to strengthen pollution-reduction strategies for any sectors subject to federal enhanced oversight or backstop actions based on the Phase I WIPs and the Bay TMDL. Planning targets were established August 1, 2011 to assist jurisdictions in developing their Phase II WIPs. These planning targets, while slightly higher than the allocations published in the December 2010 TMDL, represent the actions, assumptions, and “level of effort” necessary to meet the TMDL allocations.

The Chesapeake Bay Program (CBP) partnership is committed to flexible, transparent, and adaptive approaches towards Bay restoration and will revisit these planning targets in 2017.  The partnership will also conduct a comprehensive evaluation of the TMDL and the CBP’s computer modeling tools in 2017. Phase III WIPs will be established in 2017 and are expected to address any needed modifications to ensure, by 2025, that controls, practices, and actions are in place which would achieve full restoration of the Chesapeake Bay and its tidal tributaries to meet applicable water quality standards.

What do I need to know about the data?

2009 Baseline Presented in the "Original TMDL Allocations" View - Regulated and unregulated agriculture are combined in the agricultural sector and regulated and unregulated stormwater are combined in the stormwater sector in the pie chart at all spatial scales.  For Phase 5.3.2 information, EPA and the jurisdictions worked to determine these splits for both 2009 and the WIPs.  This was done post-December, 2010.

Progress Presented in the "Phase II WIP Planning Targets" View - Progress Run data is measured by using the most up-to-date wastewater discharge data and tracking data reported to EPA by CBP partners. Computer model simulations are used to estimate the amount of nitrogen, phosphorus and sediment delivered to the Bay resulting from annual efforts to reduce pollutants from agricultural runoff and discharges, wastewater treatment plant discharges, urban and suburban runoff and septic tank discharges, and air deposition. Pollutant loads to the Bay in any given year are influenced by changes in land-use activities and management practices, as well as the amount of water flowing to the Bay (hydrology).  Annual rain and snowfall influence the amount of water in rivers flowing to the Bay.

2017 Interim Target Bar Presented in the "Phase II WIP Planning Targets" View - The load targets portrayed are derived by calculating a 60 percent reduction of model-estimated loads between 2009 Progress and the Phase II 2025 Planning Targets.

Aggregate - Aggregated allocations are the sum of loads from multiple facilities.

Delivered Nitrogen, Phosphorus, or Total Suspended Solids – The amount of pollutant delivered to the tidal waters of the Chesapeake Bay or its tidal tributaries from an upstream point of discharge/runoff after accounting for permanent reductions in pollutant loads due to natural in-stream processes in non-tidal waters.

Download Data – If an entry shows 0, there is no allocation. If an entry shows N/A, the sector or facility is not applicable in this allocation.

Edge of Stream Nitrogen, Phosphorus, or Total Suspended Solids – The amount of pollutant reaching a simulated stream segment from a point in that stream’s watershed.

Increasing Targets - Some states show an increase from current loads to projected future loads because their milestones assume that all wastewater facilities are discharging at their full permitted capacity, rather than at projected capacity levels.

Loads – Loads are expressed in lbs/year. Loads for future years are "projected loads" and loads for past years are "delivered loads."

Nitrogen – Nitrogen means Total Nitrogen.

Permitted Facilities – Permitted facilities are significant municipal wastewater facilities defined by the jurisdiction in which it is permitted. In general, significant municipal facilities have flows larger than 0.4 million gallons per day. Wastewater discharge data are reported by the Bay jurisdictions and analyzed through the Watershed Model.

Permit In Effect – When a permit that contains an effluent limit that meets dissolved oxygen and SAV/clarity standards becomes effective, that facility is said to meet applicable water quality standards in the Chesapeake Bay and tidal waters.

Permit Issued – When a permit that contains an effluent limit that meets dissolved oxygen and SAV/clarity standards is issued but not yet effective.

Phosphorus – Phosphorus means Total Phosphorus.

Segment and Basin Allocations – The TMDL assigned allocations at the State-Segment basis, however Segments can cross multiple Basins within a single State.  The full allocation for a Segment is associated with each Basin that it crosses.

Tidal Atmospheric Deposition – Atmospheric loads of nitrogen that are directly deposited onto the Bay's tidal surface waters. Tidal atmospheric deposition allocations are only calculated for tidal segments or for the entire tidal area of the Chesapeake and are not calculated at the State, Basin, or Segment level.

Total Suspended Solids (TSS) – Small particles of solid pollutants that float on the surface of, or are suspended in, sewage or other liquids. Since TSS is predominantly sediment, total suspended solids and sediment are often used interchangeably. Total suspended solids resist removal by conventional treatment methods. In the permitted facilities tab, the columns labeled “Permit consistent with the TMDL (Issued and In Effect)” are designated N/A because evaluations of whether the permit effluent limit is consistent with the TSS waste load allocation is being conducted on a case by case basis.

What do the source sectors mean?

Agriculture – Allocations of pollutants to farmlands that are not federally regulated and contribute to the overall load allocation for a particular water body (segment).

Agriculture (Regulated) – Allocations of pollutants to farmlands that are federally regulated (e.g., concentrated animal feeding operations) and contribute to the overall waste load allocation for a particular water body.

Forest – Allocations of pollutants to forests (as part of overall load allocation) because, although wooded areas filter pollutants from the air and runoff from urban and suburban development and farmlands, ultimately, those pollutants that are not filtered out enter receiving waters from wooded areas. Forest loads will increase due to buffer and tree plantings, but this change lowers total loads since less pollution comes from an acre of forest than from agricultural or urban lands.

Load Allocation - A load allocation (LA) is the portion of a pollutant emanating from non point (or diffuse) source sectors that can enter a receiving water (segment) without violating applicable water quality standards.

LA Reserve – That portion of a segment’s load allocation that is not allocated to an existing non point source sector.

Non-Tidal Atmospheric Deposition – Allocation of nitrogen pollutants that come from air sources and are directly deposited to land surfaces in the Bay watershed not influenced by the tides.

Onsite – Allocations of pollutants to septic and other onsite systems designed to collect, treat, and disperse effluent on property owned by the individual or entity as part of the overall load allocation for a particular water body.

Regulated Stormwater – Allocations of pollutants to federally regulated industries and municipalities to be controlled by stormwater management practices. These allocations contribute to the overall waste load allocation for a particular water body.

Significant Discharge Facility - A municipal or industrial wastewater facility (defined as such by the jurisdiction in which it is permitted) is distinguished from a nonsignificant facility on the basis of flow for municipals and loads for industrials. In general, but not always, significant municipal facilities have flows larger than 0.4 million gallons per day, and significant industrial facilities discharge loads larger than 3,800 pounds per year of total phosphorus and 27,000 pounds per year of total nitrogen.

Tidal Atmospheric Deposition – Nitrogen that is added to a tidal river segment or the Bay by precipitation. Atmospheric deposition allocations are the responsibility of EPA, not the States.

Urban – Allocation of diffuse source pollutants from densely populated areas. This runoff primarily contributes to a segment’s load allocation after rain or snow events. Urban loads typically increase with development unless offset by BMPs due to growth in impervious surfaces, turf, the number of septic systems, and their associated loads.

Waste Load Allocation - A waste load allocation (WLA) is the maximum load of a pollutant emanating from point source sectors that can enter a particular waterway (segment) without violating applicable water quality standards.

Wastewater – Allocations of pollutants to municipal or industrial wastewater facilities that discharge into a particular waterway and contribute to the overall waste load allocation for that segment.

Wastewater (CSO) – Allocations of pollutants to Combined Sewer Overflows as a portion of the overall waste load allocation for a particular waterway.

WLA Reserve - That portion of a segment's waste load allocation that is not allocated to an existing point source sector or discharger.