Geoff Schaldow, director of the UC Davis Tahoe Environmental Research Center has delivered the State of the Lake Report for 2013. The report mentions the dramatic gain in clarity over the past two years. The lake clarity is the best it’s been since 2002, at 75.3 feet. The UC Davis Research Center has been recording lake clarity since 1968, when clarity was over 100 feet.
The report identifies fixes to storm drainage as a key factor in the improved lake water clarity. However, the report predicts negative impacts from climate change to start reducing water clarity in the future.
Climate change predicts extended droughts and flash flooding to reduce clarity. New questions need to be raised to understand what climate change will do to Lake Tahoe. Was Lake Tahoe warmer or cooler than the historical record last year? Are the inputs of algal nutrients to the lake declining? How much are invasive species affecting Lake Tahoe? How do these changes affect the lake’s clarity?
A host of new monitoring equipment has been put in place to help answer the previous questions. New “autonomous gliders” (underwater self-guided data recorders) can gather data at greater depths than ever before. The mixing of deep water with surface water can be measured now. There are also fixed monitoring stations at 360 feet of water off the west shore that provide real-time data.
The bottom line:
Recent trends toward better clarity are encouraging, but the long term trend shows there are many periods of apparent improvement only to be overtaken by continued decline.For a complete list of Lake Tahoe clarity readings since 1968, visit: http://terc.ucdavis.edu/research/SecchiData.pdf.