Swift, T. J.. Hydrologic Sciences, Univ. of California Davis, tjswift@ucdavis.edu
Reuter, J. J.. Dept. Envir. Sci. & Policy, Univ. of Cal. Davis, jereuter@ucdavis.edu
Goldman, C. R.. Dept. Envir. Sci. & Policy, Univ. of Cal. Davis, crgoldman@ucdavis.edu

 
FIELD AND LABORATORY APPROACHES TO QUANTIFYING CAUSES OF VARIATION IN LAKE WATER CLARITY
 
The UCD Tahoe Research Group has documented the gradual clarity loss in Lake Tahoe, CA-NV, as measured since 1959 using a Secchi disk. The average annual Secchi depth has dropped from approximately 32 m (1968) to 22 m (1996), an average loss of 0.36 m (1.2 ft.) per year. While the dominant explanation for the loss of clarity is that Lake Tahoe is in the early stages of cultural eutrophication from nutrient loading, time-series analysis of the long-term data set suggests that increased algae biomass does not explain all the variation in clarity as measured by secchi depth; fine mineral particulates from antropogenic erosion may be important. We are developing measures of the particulate and dissolved light-attenuating material in the lake to model the observed seasonal and long-term variation in water clarity, and to develop models that will help predict the effects of in-basin land use on water clarity. We have instituted a program of regular in-situ measurements of IOPs and AOPs, along with laboratory water sample analyses, with the goal of discerning the relative roles of algae and inorganic particles, and dissolved materials on seasonal and interannual scales. We present and discuss the preliminary results of these studies.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: CS61TH1131S