
ANNAPOLIS, Md. — The Chesapeake Bay Program announced Tuesday that the seven jurisdictions that make up the Chesapeake Bay watershed continued to make progress between 2023 and 2024 in reducing the amount of pollutants entering the bay.
Pollutants include nitrogen, phosphorus and sediment pollution, according to the Chesapeake Bay Program.
Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia make up the program. Under the Chesapeake Bay Total Maximum Daily Load, these jurisdictions are working to have 100% of practices in place by 2025 to reduce nitrogen, phosphorus and sediment pollution entering the Chesapeake, allowing the bay to achieve water quality standards as indicated by the program.
On an annual basis, the watershed jurisdictions report the management practices they have implemented to decrease the amount of pollution entering the bay, the Chesapeake Bay Program explains. Bay Program experts then use a suite of modeling tools to assess this information, along with data on land use, fertilizer and manure use, wastewater and septic discharges, and river flow to estimate the pollutant reductions achieved between 2009 — the baseline year for the Bay TMDL — and 2024.
Computer simulations showed the following reductions between 2009 and 2024:
- Overall nitrogen entering the Bay decreased 15.3% from 297.1 million pounds in 2009 to 251.6 million pounds in 2024, meeting 59% of the goal to reduce nitrogen by 2025.
- Overall phosphorus entering the Bay decreased 21.8% from 16.8 million pounds in 2009 to 13.1 million pounds in 2024, meeting 92% of the goal to reduce phosphorus by 2025.
- Overall sediment entering the Bay decreased 7.6% from 18.83 billion pounds in 2009 to 17.39 billion pounds in 2024, meeting 100% of the goal to reduce sediment by 2025.
“These results highlight the meaningful progress that Maryland has made with our partners to improve the waterways that sustain the Chesapeake. Through collaboration, dedication and proven strategies, we’ve achieved reductions across all sources and are nearing our targets. We’re committed to building on this momentum for lasting improvements and a healthier Bay.” said Gregorio Sandi, Vice-Chair, Chesapeake Bay Program Water Quality Goal Implementation Team and Chief, Watershed Restoration Planning Division, Maryland Department of the Environment.
The Watershed Model is updated on a regular basis with the most current data to simulate the conditions of the Chesapeake Bay watershed, according to the program. The model is refreshed when new data is added, which impacts the original pollutant reduction calculations that were determined for each jurisdiction when the Bay TMDL was put into place in 2010. According to the Chesapeake Bay Program, the most recent model update in 2024 increased the pollutant reduction calculations for each jurisdiction due to updated fertilizer data that shows a growth in its use across the watershed.
The Watershed Model shows that between 2023 and 2024, the agricultural sector was responsible for 76% of nitrogen reductions, while 46% of phosphorus and 77% of sediment reductions came from the natural sector (defined as trees, shoreline, forests and wetlands).
Estimates of phosphorus entering the Bay declined due to improved data within the Watershed Model and some jurisdictions reporting more best management practices that are effective at reducing phosphorus.
In 2024, the partnership introduced two new indicators — the Bay TMDL Indicator and the Monitored and Expected Total Reduction Indicator for the Chesapeake. According to the program, these indicators were developed after partners wanted to incorporate more water quality monitoring data to help improve the overall understanding of how the Bay watershed is responding to the implementation of best management practices and changing environmental conditions to better inform their decision-making processes and evaluation of progress. These indicators combine both modeling and monitoring data and will be updated by July.
Information on the progress that each jurisdiction is making toward meeting their goal of having 100% of practices in place by 2025 can be found on 2025 Watershed Implementation Plan Outcome webpage on ChesapeakeProgress. Final progress toward meeting this outcome will be assessed in 2026.
The Chesapeake Bay Program is currently in the process of revising the Chesapeake Bay Watershed Agreement, which includes updating this outcome. The most current information about the revision process can be found on the Planning for 2025 and Beyond website.