Clean Water

Reducing Excess Nitrogen, Phosphorus & Sediment

Outcome:

Implement and maintain practices and controls to reduce nitrogen, phosphorus and sediment. These reductions are necessary to achieve the applicable water quality standards, as described in the Bay TMDL. Those water quality standards support living resources and protect human health, as required by the Clean Water Act.

• Through 2030, signatories will continue to accelerate completion of all interim water quality planning targets through implementation of Chesapeake Bay Watershed Implementation Plans, two-year milestone commitments and other innovative strategies to achieve and maintain reduced levels of nitrogen, phosphorus and sediment.
• By December 31, 2030, revise the planning targets approved by the Principals’ Staff Committee for nitrogen, phosphorus and sediment, incorporating the latest watershed modeling, monitoring data and research findings, and develop new or amended Watershed Implementation Plans to meet the updated targets by 2040.
• Demonstrate net reductions in nitrogen, phosphorus and sediment through multiple lines of evidence, including modeling and monitoring data.

Recent Progress: Progress toward this outcome is estimated using best management practice implementation and wastewater discharge data reported by jurisdictions to the U.S. EPA Chesapeake Bay Program Office. The Bay Program Office uses the Phase 6 Watershed Model to assess nitrogen, phosphorus and sediment loads against planning targets set by the Chesapeake Bay Total Maximum Daily Load (TMDL). According to the model, best management practices implemented between 2009 and 2025 have reduced nitrogen loads by an estimated 15%, phosphorus loads by an estimated 21% and sediment loads by an estimated 7%. While practices are in place to achieve all of the sediment reductions needed to meet water quality standards by 2030, efforts to reduce nitrogen and phosphorus are off track, with practices in place to achieve only 57% of the necessary nitrogen reductions and 90% of the necessary phosphorus reductions. This outcome is considered off course. To learn more, view our: 

• Data File [XLSX, 236KB]
• Analysis & Methods Document [PDF, 493KB]
• Press Release (August 6, 2026): Chesapeake Bay watershed jurisdictions continue working toward nitrogen and phosphorus goals, with sediment goal already achieved

Lead Goal Implementation Team:

Clean Water Goal Team

Toxic & Emerging Contaminants

While chemical contamination is often characterized as a localized problem occurring in “hot spots” or “regions of concern,” toxic contaminants exceed water quality criteria in at least part of each tidal tributary that delivers water to the central channel of the Bay. These contaminants can negatively affect the survival, growth and reproduction of fish and wildlife, and pose a threat to human health when contaminated organisms are part of a person's diet.

Outcome:

Reduce the amount and effect of toxic contaminants, such as PCBs, plastics, mercury and PFAS, on the waters, lands, fisheries, wildlife and communities of the Chesapeake Bay watershed through an increased understanding of their impacts and mitigation options.

• Promote information sharing between researchers, program managers and policymakers on the lessons learned, best practices and most up-to-date science, policy and communications around the toxic contaminants impacting the Chesapeake Bay watershed.

Lead Workgroup:

Toxic Contaminants Workgroup

Water Quality, Standards Attainment & Monitoring

Monitoring the attainment of water quality standards provides the information needed to track trends in nutrient and sediment pollution and assess whether Chesapeake Bay water quality is sufficient to support aquatic life.

Outcome:

Measure changing water quality conditions by maintaining monitoring networks and tracking our collective progress toward achieving clean water, throughout the Chesapeake Bay and its watershed.

• Maintain full core monitoring network operations (i.e., nontidal water quality, SAV, tidal water quality, benthic and community science) annually to support analysis and communication of water quality loads, trends and criteria attainment.
• Develop and expand partnership-approved approaches for assessing whether water quality criteria are being met for all designated uses. For dissolved oxygen criteria, establish an approved method by 2028 and apply the method for data analysis and reporting by the end of 2030.
• Maintain or exceed the rate of improvement in the water quality standards attainment indicator relative to the 1985-2022 baseline.
• Analyze and report status/loads, trends and factors affecting those trends for nontidal and tidal water quality.

Recent Progress: Progress toward this outcome is measured using multiple indicators, including monitored nutrient and sediment loads to the Chesapeake Bay and the estimated attainment of water quality standards in the Bay's tidal waters. These indicators are assessed and reported each year. Progress toward this outcome is also determined by the status of our monitoring programs—which have been maintained across the region—and our efforts to develop and refine partnership-approved approaches for evaluating progress toward criteria attainment—which are actively underway.

Annual nutrient and sediment loads are driven largely by hydrologic conditions, or the way precipitation, river flow and runoff move through the watershed. In 2024, monitored nutrient and sediment loads at 123 non-tidal river stations across the watershed showed mixed results, with loads increasing in some rivers and decreasing in others. While nitrogen, phosphorus and sediment loads to the Bay increased between 2023 and 2024, these loads remained below the long‑term (1985-2024) average despite above-average streamflow. This indicates rivers are carrying smaller amounts of nutrients and sediment into the Bay and suggests management actions and other factors are helping reduce pollutants. Over the long term, trends in nitrogen loads have shown a significant decrease, while trends in phosphorus and sediment loads have shown smaller declines.

A multi-metric indicator that combines dissolved oxygen, chlorophyll a and water clarity/submerged aquatic vegetation data across 92 management segments allows us to estimate progress toward water quality standards attainment in the Bay’s tidal waters. The indicator’s most recent results show an estimated 29% of the Bay and its tidal tributaries met water quality standards from 2022-2024—far below the 100% target. Over the long term, the rate of improvement is positive but remains below the 0.2%-per-year goal. Long-term changes in water quality reflect the cumulative effects of management actions and human activities in the watershed. The partnership’s water quality indicator provides a Bay-wide estimate of overall progress using shared monitoring data, but it does not replace official state regulatory assessments. Individual states hold the legal authority under Clean Water Act Sections 303(d) and 305(b) to issue official water quality assessments and impairment listings in their even-numbered year Integrated Reports. A formal complete assessment of all dissolved oxygen criteria to evaluate the attainment of standards is not available currently. More information is available in Maryland’s Integrated Report and Virginia’s Integrated Report. 

Progress toward this outcome is considered on course. To learn more, view our:

• NPS Loads Data File [XLSX, 90KB] and Analysis & Methods Document [PDF, 461KB]
• Water Quality Standards Attainment Data File [.XLSX, 101KB] and Analysis & Methods Document [PDF, 790KB]

Lead Goal Implementation Team:

Clean Water Goal Team