Periphyton Monitoring Program Review

The accumulation of periphyton (attached algae) on natural rock surfaces, piers, boats and other substrates is perhaps the most striking indicator of Lake Tahoe’s water quality for the largely shore-bound population. The Lahontan Water Board, has funded periphyton monitoring in Lake Tahoe since 1982. Monitoring occurred for select periods in the 1980s (1982-85) and 1990s (1989-93). Near-continuous monitoring has occurred since 2000 with a one-year gap in 2004.

 
In 2015, the UC Davis Tahoe Environmental Research Center (TERC) prepared an analysis of existing periphyton data for the Tahoe Regional Planning Agency (TRPA) to inform the evaluation of the threshold standard related to nearshore attached algae. Statistical analyses found no significant lake-wide trends in periphyton biomass during the 1982-2015 monitoring period. 

The Lake Tahoe Nearshore Evaluation and Monitoring Framework recommended that periphyton monitoring using the methodology and intensity consistent with historic efforts should be continued. In anticipation of updating monitoring, UC Davis provided the Lahontan Water Board with a series of program improvement suggestions to enhance periphyton monitoring effectiveness. 

​

Resource management agencies sought an ‘engaged review’ of the existing periphyton monitoring program to assess its efficacy to track lake-wide periphyton status and trends. Review findings will be used to guide investment in the most cost-effective and defensible periphyton monitoring methods to evaluate ongoing periphyton biomass status and trends at representative locations around Lake Tahoe. 

​

Contact for further information: Alison Toy, natoy@ucdavis.edu