Pacific Southwest Research Station

Development of status and trend indicators for stream condition and other resources

Principal Investigators:
Andrew Stubblefield, Humboldt State University
Alison O’Dowd, Humboldt State University
Chad Praul, Environmental Incentives, LLC

Proposal [pdf]

Final Report [pdf]

Drinking Water Quality Indicator Reporting Options for the Tahoe Basin report [pdf]

Please contact Dr. Andrew Stubblefield with questions regarding the reports and data files presented below.

Project Summary:
This study evaluated the status and trend of benthic macroinvertebrate data collected in 2009 and 2010 from 85 sites located within 29 watersheds of the Tahoe Basin. Approximately 56% of streams sampled in 2009 and 2010 were categorized as “Excellent,” 18% were categorized as “Good”, while 26% were “Marginal.”

Trend analysis of a sub‐set of sites revealed no significant differences between the 12 sites sampled in 2003 and nearby sites sampled in 2009‐2010. Precipitation and discharge were near average for the years examined, so climate was not likely to have exerted a bias on this assessment of the status and trends of aquatic resources for these years. There was no apparent relationship between biological condition and the percentage of impervious surface in the upstream watershed; this may be a result of overall low levels of impervious surfaces basin‐wide.

An investigation of habitat variables with biological condition found that Marginal sites tended to have higher water temperatures, more glide and pool habitat, larger coverage of non‐woody vegetation and more fine sediment. Habitat variables associated with better biological condition included more riffle habitat, boulders, higher slope and dissolved oxygen. Specific Marginal sites seemed to have common sources of degradation including lower stream flow discharge, more bank erosion and more sand and fine streambed substrate.

The stream evaluation methods presented in this study are meant to serve as a model for future assessment of streams in the Lake Tahoe Basin.

Example Status and Trend Reports:
Indicator Summary—California Spotted Owl [pdf]
Indicator Summary—Willow Flycatcher [pdf]
Indicator Summary—Vertical Extinction Coefficient [pdf]

Data sets that accompany the drinking water quality analysis:
Tahoe Water Suppliers Association All Purveyor Raw Data [xlsx]
Incline Village General Improved District Stream and Lake Sampling [xlsx]
Nevada Drinking Water Quality Sampling (bacteriological data) [xlsx]
Nevada Drinking Water Quality Sampling (all other parameter data) [xlsx]
Consumer Confidence Report data from nine suppliers [xlsx]

Data sets that accompany the indicator summary reports:
Vertical Extinction Coefficient data from UC Davis [xlsx]
California Spotted Owl Data [xlsx]
Willow Flycatcher data [xlsx]