USDA Forest Service

Pacific Southwest Research Station

Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Potential for pathogen growth, fecal indicator growth and phosphorus release under clam removal barriers in the Lake Tahoe Basin

Principal Investigators:
Stefan Wuertz, University of California-Davis
Geoff Schladow, University of California-Davis

Proposal [pdf]

Final Report [pdf]

Please contact Dr. Stefan Wuertz with questions regarding the final report.

Project Summary

A rapid increase in the Asian clam (Corbicula fluminea) population, an invasive species considered to be a major threat to Lake Tahoe, has been reported in the lake since 2008. One possible remedy to manage the spread of Asian clams is placing rubber barriers on top of clam beds, which creates anoxic conditions that eventually suffocate the clams underneath. Although a pilot-scale experiment conducted in Lake Tahoe showed that Asian clams were effectively killed by this treatment, it is necessary to evaluate the water quality impacts prior to its large-scale implementation.

Using microcosm laboratory experiments that mimicked winter and summer-like conditions under the rubber barriers, this project examined:

  1. Whether fecal indicator bacteria such as total coliforms, fecal coliforms, Escherichia coli and enterococci re-grow under the barrier.
  2. Whether artificially added human pathogens (Campylobacter jejuni and Salmonella enterica) re-grow and/or persist.
  3. Whether alternative fecal indicator bacteria such as universal-, human-, dog- and bovine-associated Bacteroidales re-grow.
  4. The amount of ammonium, phosphate and dissolved organic carbon released under the barrier as a result of decaying Asian clams.