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Navigating toward a cleaner Chesapeake Bay

September 27, 2023

Following the 2019-2021 assessment period, the Chesapeake Bay Program reported that 28.1% of the Bay and its tributaries met water quality standards, a slight decline from the previous period. The decrease was attributed to excessive rainfall in 2018 and 2019; runoff carried nitrogen, phosphorus, and sediment pollutants into the waterbody.

Efforts to monitor water quality and reduce pollution have shown progress. Computer simulations indicate a 14% reduction in overall nitrogen, a 13% decrease in phosphorus, and almost 5% reduction in sediment since 2009.

To estimate progress toward meeting 2025 nitrogen, phosphorus and sediment goals as outlined in the Chesapeake Bay Watershed Agreement, three indicators are currently used: dissolved oxygen, water clarity or underwater grass abundance, and chlorophyll a (a measure of algae growth)

Starting in 2024, two new indicators — the Integrated Chesapeake Bay Watershed Total Maximum Daily Load (TMDL) for Nitrogen and (TMDL) for Phosphorus — will be integrated with the existing three to improve understanding of the watershed’s response to best management practices being implemented.

A comprehensive network of monitoring stations and sophisticated modeling tools allow the Chesapeake Bay Program to assess progress and refine strategies, especially in addressing non-point sources. The USGS-led partnership with local jurisdictional partners collects data from 123 stations in non-tidal waters across the region. Recent analysis of nitrogen, phosphorus, and sediment pollution using network monitoring data during 2011-2020 showed mixed results with some stations improving and others worsening.

The importance of accurate data in shaping policies, practices and pollution estimates is reinforced as the best available information sources insights and supports ongoing restoration efforts. The Chesapeake Bay Program can more accurately track jurisdictional-specific progress toward their pollutant reduction goals and give partners science-based information to continue to improve water quality and the and health of the Bay.

To assist water quality managers, we supply water quality monitoring instrumentation and long-term water quality data management software to ensure a holistic understanding of watershed health. Accurate probes and advanced analytics enable local jurisdictions as well as state and regional partners to share quality-assured data to calculate TMDLs and project pollution estimates as they identify opportunities and threats to reaching 2025 clean water goals.