Chesapeake Bay Program model estimates decline in nutrients, sediment

The Chesapeake Bay Program announced today that the seven jurisdictions that make up the Chesapeake Bay watershed–Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia–continue to make progress in reducing the amount of nitrogen, phosphorus and sediment pollution that is flowing into the Chesapeake Bay.

Under the Chesapeake Bay Total Maximum Daily Load (Bay TMDL), each jurisdiction strives to have 100% of practices in place by 2025 that will reduce nitrogen, phosphorus and sediment pollution, allowing the Chesapeake Bay to achieve water quality standards.

The Chesapeake Bay Program uses a sophisticated suite of modeling tools that show how much pollution is estimated to be reduced by best management practices reported by the watershed jurisdictions each year. These tools also approximate the pollution reductions that have occurred between 2009—the baseline year for the Bay TMDL—and 2023.

• Overall nitrogen entering the Bay decreased 17% from 297.8 million pounds in 2009 to 247.6 million pounds in 2023, meeting 57% of the goal to reduce nitrogen by 2025.

• Overall phosphorus entering the Bay decreased 17% from 17.2 million pounds in 2009 to 14.2 million pounds in 2023, meeting 67% of the goal to reduce phosphorus by 2025.

• Overall sediment entering the Bay decreased 6% from 18.9 billion pounds in 2009 to 17.8 billion pounds in 2023, meeting 100% of the goal to reduce sediment by 2025.

The model shows that between 2022 and 2023, the agricultural sector was responsible for 43% of nitrogen reductions and 26% of phosphorus reductions. The wastewater sector, during the same period, was responsible for 53% of nitrogen reductions and 67% of phosphorus reductions.

The following information demonstrates the progress that each jurisdiction is making toward meeting their goal of having 100% of practices in place by 2025 to reduce nitrogen, phosphorus and sediment pollution:

• Delaware has achieved 9% of its 2009-2025 reduction goal for nitrogen, 39% of its reduction goal for phosphorus and 64% of its reduction goal for sediment. The state did not meet its 2023 pollution reducing targets for nitrogen, phosphorus and sediment.

• The District of Columbia has achieved 100% of its 2009-2025 reduction goals for nitrogen, phosphorus and sediment. The District is on track to meet each one of its 2023 pollution reducing goals.

• Maryland has achieved 83% of its 2009-2025 reduction goals for nitrogen, 100% of its reduction goal for phosphorus and 100% of its reduction goal for sediment. The state did not meet its 2023 pollution reducing targets for nitrogen.

• New York has achieved 65% of its 2009-2025 reduction goals for nitrogen, 66% of its reduction goal for phosphorus and 26% of its reduction goal for sediment. The state did not meet its 2025 reduction targets for nitrogen, phosphorus and sediment.

• Pennsylvania has achieved 29% of its 2009-2025 reduction goal for nitrogen, 50% of its reduction goal for phosphorus and 58% of its reduction goal for sediment. The Commonwealth did not meet its 2023 pollution reducing targets for nitrogen, phosphorus and sediment.

• Virginia has achieved 80% of its 2009-2025 reduction goal for nitrogen, 62% of its reduction goal for phosphorus and 100% of its reduction goal for sediment. The Commonwealth did not meet its 2023 pollution reducing targets for nitrogen and phosphorus.

• West Virginia has achieved 100% of its 2009-2025 reduction goal for nitrogen, 91% of its reduction goal for phosphorus and 100% of its reduction goal for sediment. The state is on track to meet each one of its 2023 pollution reducing targets.

Facts

Through the Chesapeake Bay Watershed Agreement, the Chesapeake Bay Program has committed to having 100% of practices in place by 2025 that would achieve all the nitrogen, phosphorus and sediment reductions necessary to meet the goals outlined in the Bay TMDL. These estimates are generated by the Watershed Model and are derived, in part, from land use data, the implementation and effectiveness of best management practices and water quality monitoring data. The Chesapeake Bay Program assesses water quality by the amount of dissolved oxygen in the Bay, chlorophyll a (a measure of algae growth) and water clarity (using underwater grass acreage).

The Environmental Protection Agency (EPA) uses the modeled nitrogen, phosphorus and sediment pollution estimates to evaluate whether jurisdictions are on track to meet the Bay TMDL reduction goals and their associated two-year milestone commitments. The EPA anticipates that it will release its evaluation of the 2022-2023 final progress and 2024-2025 two-year milestones in mid-May 2024.

Issues

Excess nitrogen, phosphorus and sediment are among the leading causes that contribute to the Bay’s poor water quality. Nitrogen and phosphorus can fuel the growth of algae blooms that lead to low oxygen “dead zones” that negatively impact marine life. Sediment can block sunlight from reaching underwater grasses, suffocating shellfish that rely on them for their habitat.

Best management practices used in backyards, in cities and on farms can reduce the flow of nitrogen, phosphorus and sediment into waterways. Actions taken to decrease pollution from point sources (e.g., wastewater treatment plants) may immediately show detectable changes, but regarding the implementation of conservation practices for non-point sources (e.g., runoff that may include fertilizer or chemicals), there is often a delay in measuring their impact on improving water quality and the health of the Bay.

Importance

By incorporating the best available data into our computer simulations and pollution estimates, the Chesapeake Bay Program can more accurately track our partners’ progress toward their pollution-reducing goals. These data give state agencies and local leaders the science-based information they need to assess their strategies for reducing pollution and tweak if necessary.

Tracking the progress that each jurisdiction is making toward reducing nitrogen, phosphorus and sediment pollution entering not only the Chesapeake Bay, but also their local waterways, helps to improve overall water quality, restore habitats and increase the populations of many plant and animal species. By providing a more accurate picture of pollution in the watershed, the partnership is able to better understand what actions are needed to restore water quality as we work toward an environmentally and economically sustainable Chesapeake Bay watershed.

Quotes

“Chesapeake Bay Program partners continue to install practices that will further reduce nutrient and sediment loads entering the Bay. The sediment target has been met across the watershed, and we recognize that opportunities remain to reduce nutrients to meet our 2025 water quality goal. We strive to build upon our current successes, focus our efforts on what works well, prioritize innovation and explore additional actions that will help us meet and sustain our water quality goals.”

• Suzanne Trevena, Chair of the Chesapeake Bay Program Water Quality Goal Implementation Team and Chesapeake Bay Regulatory Manager, Water Division, U.S. Environmental Protection Agency Mid-Atlantic Region

“Over the last decade, AlexRenew is one of many wastewater utilities in the Chesapeake Bay watershed that has made significant investments to benefit the health and quality of the Bay and the communities we serve. Each year, AlexRenew prevents 2,400 tons of nitrogen and 300 tons of phosphorus from impacting the Bay. Our continued commitment to supporting the Bay goals is also being realized through the RiverRenew project which will prevent over 120 million gallons of combined sewage from entering the Potomac River and Bay each year. This once-in-a-generation project is anticipated to be complete by 2026 to support a fishable and swimmable future.”

• Justin Carl, Co-Chair Chesapeake Bay Program Wastewater Treatment Workgroup and General Manager and CEO, Alexandria Renew Enterprises

“Reducing nitrogen, phosphorus and sediment pollution entering the Chesapeake Bay is an enormous task, and the Alliance knows that the path to a healthy Bay is working together to deliver long-term and committed action at the source. We've achieved this through our Corporate Sustainability work by giving everyone a set at the table. By supplying diverse funding, expertise, perspectives, capabilities and clean water solutions across dairy and poultry farms, we are proud to play a significant role in helping to lower the pollution that is entering not only the Chesapeake Bay but also our local waters in communities upstream.”

• Kate Fritz, Chief Executive Officer, Alliance for the Chesapeake Bay