Assessing the nation's fluvial systems using a landscape approach: Improving opportunities for protection and restoration

Habitat degradation from landscape disturbances has severely impacted the Nation’s streams and rivers, and understanding the varied sources, extent, and severity of impairment is critical for supporting large-scale protection and restoration efforts. Historically, the U.S. lacked a comprehensive and objective tool applicable to all rivers; data and approaches were not available for assessing conditions in all systems over such large regions. However, by using the landscape approach and integrating large-scale factors known to affect stream habitat, we have attempted to meet this need. Our national assessment is built on a hierarchical assessment framework that incorporates data and provides assessment results across multiple areas from river reaches to basins to ecoregions. It also facilitates data exchange, ensuring that results can inform other efforts and that new information can refine scores. Our analytical approach generates scores based on disturbances summarized in local and network catchments to characterize influences of multi-scale controls on different stream habitat factors, and we have attempted to account for regional differences in controls by considering relationships between disturbances and biological metrics. Our assessment results offer new insights into the condition of fluvial systems nationally and are currently being used by regional and national efforts to guide management.