The picture above shows a view from Clear Lake State Park over Soda Bay and the Narrows near Glenhaven, which “divide” the lake in a north and a south part. The water of the lake is not clear, since its shallow body of water is naturally rich in nutrients (eutrophic): algae and cyanobacteria are native to Clear Lake. They grow, depending on cool or warm weather conditions, rise to the lake surface and decay into foul-smelling organic matter . Notice that foul-smelling gases do not necessarily affect the clarity of air.
To conclude with a clear advice: avoid drinking untreated lake water and enjoy breathing the clear air in the vicinity of the lake.
Keywords: geography, vulcanology, ecosystems, Native Americans, history.
References and more to explore
 Terry Knight: In the Clear. Bay Nature April-June 2013, 23 (2), pp.12-15 [Apr-Jun 2013 Issue: baynature.org/issue/apr-jun-2013/].
 DavisWiki: Clear Lake [daviswiki.org/Clear_Lake].
 California's Lake County: Clear Lake [www.lakecounty.com/AboutLC/Explore/ClearLake.htm].
 California's Lake County: Mount Konocti [www.lakecounty.com/AboutLC/Explore/Konocti.htm].
 Sierra Club: What's Going on with Clear Lake? Some questions and answers [www.redwood.sierraclub.org/lake/CLQ.A.htm].