Predicting stream flow statistics in the ungaged watersheds of the Lake Tahoe Basin for fisheries habitat assessment (Nevada, California)

This study predicts a stream's potential to provide optimal habitat for salmonid species in the tributary streams of the Lake Tahoe Basin. Predictions are based on coupled estimates of flow regime and instream flow requirements for both the gauged and ungauged streams. Statistical relationships are established correlating recorded flow regimes with individual geographic and geomorphic watershed attributes. In the same manner, correlations are established between recorded instream flow requirements for selected streams in the Lake Tahoe Basin with watershed attributes. With robust statistical relationships established, estimates of flow statistics and optimal instream flow requirements are made for 55 selected streams. Once these estimates are coupled, a streams potential can be assessed. It is estimated that few of the Lake Tahoe tributary streams have flow conditions to provide optimal habitat conditions for salmonid species. In every modeled stream, flow conditions to maintain optimal habitat have a less than 50% probability of occurring during the summer and early fall months. The winter months are only slightly better, while the spring snow melt months have a significantly higher probability of maintaining optimal habitat.