Viers, JH, JD Kiernan, S Purdy, AM King, and PB Moyle. 2007. Comparative Analyses of Ecological Integrity Indices as Applied to Waters of the Mokelumne River Watershed. 43 ppd. Center for Watershed Sciences, University of California, Davis, Davis, CA. A Report to the Resource Legacy Fund Foundation (Sacramento, CA)

Freshwater resources and ecosystems are globally impaired by human activities and acutely
stressed throughout California, including the rivers and streams of the Sierra Nevada. We
assessed the condition of the Mokelumne River, a representative watershed located in the
central Sierra Nevada, at multiple scales to meet three explicit objectives. One, we developed
indices of biotic integrity to represent the conditions of fishes, benthic macroinvertebrates, and
habitat found in representative locations at the site‐specific scale.  Two, we developed a
watershed‐scale index of riverine integrity to characterize the ecological state of all streams
within the basin. Three, we performed the first explicit comparison of integrity indices to assess
how well traditional instream‐based methods correspond to those developed at the watershed
scale.  Our results indicate that hydrologic alteration from hydroelectric power operations has a
significant negative influence on the integrity of streams as measured by both fish and benthic
macroinvertebrate integrity indices. We found no significant relationship between habitat
integrity and hydrologic alteration, suggesting that studies using only measures of instream
habitat condition may not be able to detect impairment. Our explicit comparison across scales
suggests that future studies can use GIS‐based, watershed‐scale indices of integrity to evaluate
riverine integrity widely across basins.