Pacific Southwest Research Station

Predicting and managing changes in near-shore water quality

Conditions in the near-shore zone of Lake Tahoe have degraded owing to the establishment and spread of invasive fishes and aquatic plants, and increased concentrations of periphyton (attached algae) on rocks, piers, and other hard substrates. The near-shore zone suffers pollution from marinas and accidental spills. Consequently, management strategies to improve clarity in the middle of the lake will not necessarily improve conditions in the near-shore zone. This research will improve understanding of these processes to help develop scientifically sound management strategies and thresholds.

Lead Researchers: S. Geoffrey Schladow, University of California, Davis; Rick Susfalk, Desert Research Institute; Alan Heyvaert, Desert Research Institute; Sudeep Chandra, University of Nevada, Reno; Francisco Rueda, Universidad de Granada; Fabian Bombardelli, University of California, Davis

Final Report [pdf 9.5 MB]

Goal: Understand and assemble a dataset on clarity, periphyton growth, fate of pollutants, and spread of nonnative plants and fishes in near-shore environment

Sites: Sensor arrays at Timbercover pier and Tahoe Keys plus one additional site to be determined. Intensive study area in South Lake Tahoe to include intensive monitoring of fish.

Products

1. A calibrated 3-D hydrodynamic, thermodynamic, particle tracking and scalar transport model of the near-shore zone of South Lake Tahoe that can be extended to other near-shore areas.
2. Report on determinants of water clarity, periphyton growth, spread of nonnative species and the relative importance of sediment resuspension, streamloads and intervening zone loads of fine particles and nutrients. This will form the basis of a conceptual model of the near-shore zone.
3. Report on spatial survey of near-shore conditions for the entire lake, including the distribution of fish, periphyton and nonnative aquatic plants in the near-shore zone.
4. Report on effectiveness of potential near-shore management strategies and evaluation of impacts on individual water quality issues.
5. Report on current and improved water quality standards.