By 2025, have all practices and controls in place to achieve applicable water quality (i.e., dissolved oxygen, water clarity/submerged aquatic vegetation and chlorophyll a) standards as articulated in the Chesapeake Bay Total Maximum Daily Load.
As of 2019, best management practices (BMPs) to reduce pollution are in place to achieve 39% of the nitrogen reductions, 49% of the phosphorus reductions and 100% of the sediment reductions needed to attain applicable water quality standards when compared to the 2009 baseline established in the Chesapeake Bay Total Maximum Daily Load (Bay TMDL).
According to the Chesapeake Assessment Scenario Tool (CAST), BMPs (pollution controls) put in place in the Chesapeake Bay watershed between 2009 and 2019 lowered nitrogen loads 11%, phosphorus loads 10% and sediment loads 4%. According to BMP and wastewater data from jurisdictions, and the watershed conditions incorporated in CAST, the reductions in estimated nitrogen and phosphorus pollution loads between 2009 and 2019 are mostly due to upgrades to wastewater treatment facilities. The reductions in sediment loads are primarily from the agricultural sector. Between 2018 and 2019, nitrogen loads decreased an estimated 0.5% compared to the average annual load change of 1.2%, phosphorus loads increased an estimated 3% compared to the average annual load reduction of 1.5%, and sediment loads decreased an estimated 0.6% compared to the average annual load reduction of 0.4%.
Modeled Nitrogen Loads to the Chesapeake Bay (1985-2019)
Loads simulated using CAST17 and jurisdiction-reported data on wastewater discharges.
The Chesapeake Bay Program’s nutrient pollution load estimates were generated using the Phase 6 version of CAST (also known as CAST17) and wastewater discharge data reported by jurisdictions and calibrated using monitoring data. For detailed descriptions of CAST, please visit the CAST Model Documentation website.
Jurisdictions have described the steps they are taking to reduce pollution and achieve the Bay TMDL allocations in their respective Watershed Implementation Plans (WIPs). Jurisdictions developed and submitted Phase I WIPs in 2010, Phase II WIPs in 2012 and Phase III WIPs in 2019. Final planning targets for sediment and source sectors have been established since last year’s reporting period. All other planning target loads were adjusted after the jurisdictions’ Phase III Watershed Implementation Plans (WIPs) were finalized in 2019 using the same process that established the Bay Total Maximum Daily Load (TMDL) in 2010.
Resource availability, location and other factors can influence a jurisdiction’s decision and ability to implement certain practices in certain sectors. More information about nitrogen, phosphorus and sediment loads and practices can be found on the CAST website. Programmatic milestones are maintained and updated every two years on the websites of each jurisdiction: Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia. The next milestone period is 2020-2021.
The Chesapeake Bay Program also uses water quality monitoring data to track the partnership’s progress towards attaining water quality standards and to examine trends in reducing nitrogen, phosphorus and sediment in the watershed.
Participating partners have described the steps they will take to achieve the 2025 Watershed Implementation Plan (WIP) outcome in their individual WIPs. To track the achievement of these outcomes, partners have committed to:
Collecting, verifying and reporting BMP data;
Evaluating the effectiveness of pollution controls;
Enhancing water quality monitoring efforts; and
Adhering to the TMDL Accountability Framework.
Monitoring and assessing progress toward the 2017 WIP outcome occurred through the 2017 Midpoint Assessment. This review of 2017 progress led to enhanced modeling tools that addressed emerging issues like climate change and the TMDL Accountability Framework, which helps provide confidence that the necessary pollution reductions will occur to achieve the 2025 WIP outcome.
As part of the Chesapeake Bay Program’s partnership-wide implementation of adaptive management, progress toward the 2025 outcome will again be reviewed and discussed by the Management Board in August of 2020.