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Mapping Watershed Integrity for the Conterminous United States
Citation:
Thornbrugh, D., S. Leibowitz, J. Flotemersch, R. Hill, AND J. Stoddard. Mapping Watershed Integrity for the Conterminous United States. American Fisheries Society Meeting, Portland, OR, August 16 - 20, 2015.
Impact/Purpose:
A watershed integrity (WI) index and a national map of WI for the conterminous United States (CONUS) are being developed under the Safe and Sustainable Water Resources National Program. The index will map WI by evaluating risk factors that can impact six key functions associated with watershed integrity. The resulting map could provide a powerful tool for EPA’s Office of Water to consistently compare WI for the nation. This information could similarly be useful for state environmental and natural resource agencies. The WI index can also be decomposed into specific factors that influence index scores that can be targeted for adaptive management by informing protection, rehabilitation, and restoration efforts in watersheds. This WI index will provide a watershed integrity value for all ~2.65 million stream catchments associated with the National Hydrography Dataset Plus Version 2 (NHDPlusV2). An initial map is expected at the end of FY15.
Description:
Watersheds provide a variety of ecosystem services valued by society. Production of these services is partially a function of the degree to which watersheds are altered by human activities. In a recent manuscript, Flotemersch and others (in preparation), defined watershed integrity (WI) as the “capacity of a landscape, contributing surface water to a single location, to support and maintain the full range of inherent ecological processes and functions essential to the long term sustainability of local biodiversity and the watershed resources and services provided to society.” Six key functions must be present for a watershed to have integrity: hydrologic regulation, regulation of water chemistry, sediment regulation, hydrologic connectivity, temperature regulation, and habitat provision. We developed and mapped an index of WI for the conterminous USA (CONUS) based on these six key functions by incorporating human landscape stressors that have been shown to degrade key functions in watersheds. A WI index and map for the CONUS provides a consistent way to compare WI across the nation. The WI index can also be decomposed into specific factors that influence index scores that can be targeted for adaptive management by informing protection, rehabilitation, and restoration efforts in watersheds.