ANNAPOLIS, Md. — The Chesapeake Bay Program released its most comprehensive dataset to date on June 26, 2025, updating its High-Resolution Land Use/Land Cover Data and Change Data and introducing new Hyper-Resolution Hydrography Data. These datasets provide precise insights into the Chesapeake Bay watershed’s land management and waterway networks, aiding restoration efforts across 99,000 square miles. Available for public use, the data are accessible via the U.S. Geological Survey ScienceBase-Catalog.
The updated Land Use/Land Cover Data, covering 2013/2014, 2017/2018, and 2021/2022, offer a 1-meter resolution map of the watershed, categorizing 56 land-use types, including forests, croplands, and roads, with 95% accuracy. These data enable state and county planners, conservation groups, and others to target restoration strategies effectively. The Land Use/Land Cover Change Data, covering the same periods, track development, agriculture, and natural landscape shifts with 96% capture accuracy and 77% precision. These insights guide policies balancing economic growth and environmental health. An update on tree canopy, forest cover, and impervious surfaces will follow later this summer.
The new Hyper-Resolution Hydrography Data mark a significant advancement, mapping more than twice the stream channel miles compared to prior national data. With 94% accuracy for previously mapped streams and 67–82% for unmapped ones, the dataset details stream locations, dimensions, and connectivity. This comprehensive inventory supports flood control, fish passage, stream restoration, and pollutant management, addressing critical environmental challenges.
“High-resolution land use and land cover data and hyper-resolution hydrography data are foundational, authoritative, and game changing to environmental restoration and conservation,” said Peter Claggett, research geographer with the U.S. Geological Survey and lead, Chesapeake Bay Program Land Data Team. “The data are foundational to a wide variety of environmental assessments and geographic analyses because they describe the human-modified and natural landscape and how both have changed over time. The data are authoritative because they are both accurate and transparent with easily recognizable features such as roads, structures, and tree canopy. Most importantly, the data are game changing, enabling the identification of restoration and conservation opportunities throughout the Chesapeake Bay watershed at local scales down to individual farms, forest tracts, and developments.”
The datasets support the Chesapeake Bay Watershed Agreement and Total Maximum Daily Load planning, helping jurisdictions meet pollutant reduction goals. Partners, including the Chesapeake Conservancy, U.S. Geological Survey, University of Vermont Spatial Analysis Lab, U.S. Environmental Protection Agency, and University of Maryland, Baltimore County, collaborated on the project. All datasets are open-source and free, fostering widespread use in community planning, flood safety, and conservation.
“Maps such as these do more than show locations, they are tools for a host of societally-relevant applications and a record of environmental conditions in time,” said Matthew Baker, Ph.D., professor of geography & environmental systems at the University of Maryland, Baltimore County. “The good news is that the time increment between the dusty old and the shiny new maps is shrinking. The Bay Program is supporting new ways of accelerating this process to the point where such maps can be used to help monitor the dynamics of landscape change as well as its status. What’s exciting is that the new mapping procedures are not just making mapping easier, they are also providing useful new measurements, leading to further discovery and expanding our understanding of both the natural and built environment.”
The Hyper-Resolution Hydrography Data reveal previously unmapped headwater streams, which play a critical role in linking land conditions to Bay water quality. “We now have tools to drive the most efficient and effective conservation of the Chesapeake Bay watershed yet,” said Michael Evans, Ph.D., deputy director and lead data scientist at the Chesapeake Conservancy’s Conservation Innovation Center. “The new hyper-resolution hydrography data will transform how the Chesapeake Bay is managed and restored. This innovative approach to stream mapping reveals more than twice as many stream miles than were previously mapped. Most of these are small headwaters—the capillaries that play an outsized role in linking what happens on the land to conditions in the Bay. Combined with the detailed understanding of land use dynamics that three time periods of high-resolution land cover data provide, decision makers can evaluate policies, forecast future scenarios, and take actions to improve water quality with unprecedented precision.”
The datasets’ high resolution allows for precise targeting of restoration efforts, such as identifying areas for reforestation or stream buffer enhancements. Local governments can use the data to plan infrastructure improvements, like culverts for fish passage or flood mitigation systems. Conservation groups can prioritize land purchases or easements based on detailed habitat data. The open-source nature ensures broad access, encouraging collaboration across jurisdictions.
Historically, the Chesapeake Bay Program has driven data-driven restoration since its establishment in 1983. The 2014 Watershed Agreement set ambitious goals for water quality, habitat restoration, and land conservation, which these datasets directly support. By providing a clearer picture of land and water dynamics, the data empower stakeholders to make informed decisions, ensuring the Bay’s long-term health.
