Assessing the Condition and Vulnerability of Healthy Watersheds Across the Chesapeake Region

The Chesapeake Bay Program, through its Maintain Healthy Watersheds Goal Implementation Team, works with state partners towards a goal of maintaining the long-term health of watersheds identified as healthy by each of the individual jurisdictions. Quantitative indicators are important to assess current watershed condition, track future condition, and assess the vulnerability of healthy watersheds to future degradation. The Chesapeake Healthy Watersheds Assessment (CHWA) provides a set of metrics characterizing multiple aspects of watershed health, in broad categories of landscape condition, hydrology, geomorphology, habitat, biological condition, and water quality. Geospatial analyses leverage data from Chesapeake Bay high-resolution land use / land cover and other regional data sources. In addition, a set of vulnerability metrics were derived representing aspects of land use change, climate change, and other risk factors. Metric values were compiled for the nearly 84,000 NHDPlus (v.2) catchments Bay-wide and combined to create overall Watershed Health index scores. Recent updates for a Maryland Healthy Watersheds Assessment pilot include integration of new data for land use / land cover, flow alteration, streambank sediment, and conductivity, along with several state-specific metrics and a refined definition of riparian areas. Predictive power of candidate metrics will be tested using Maryland Biological Stream Survey bioassessment data as response variables. The assessment framework, metrics, and geodatabase created for the CHWA and state-specific refinement are intended to be useful for a variety of management applications, primarily to support strategies to protect and maintain watershed health. In particular, indicators of vulnerability may provide an “early warning” to identify factors that could cause future degradation, allowing for actions to be taken to maintain watershed health.