Toxic Cyanobacteria Choke Water Systems Around California’s Clear Lake
Toxic blooms are a public health risk and increase water treatment costs.
Researchers from the University of California, Davis, are studying Clear Lake in order to understand how nutrients and water circulate within the lake system. From their research vessel the R/V Ted Frantz, the scientists take water quality samples at seven sites every six to eight weeks. Their results will inform state and local responses to the harmful algal blooms.
The Big Valley Band of Pomo Indians has a sliver of land on the flat, fertile western shores of Clear Lake. The tribe’s Environmental Protection Agency began a cyanobacteria monitoring program in 2014 after an exceptionally bad year for toxic blooms on the lake. The monitoring program has influenced a number of additional state studies as well as drinking water testing requirements for utilities that use the lake as a supply source.
One of the worst spots on the lake for harmful algal blooms is Clear Lake Keys, a residential community connected by artificial canals. Blooms peak in the late summer and early fall, though toxin levels in 2020 remained high through November.
Eighteen drinking water utilities use the lake as a water source. Konocti County Water District, which has an intake at this site, has seen operating and treatment costs rise due to harmful algal blooms. A district with a high poverty rate, Konocti received a $10 million state grant to overhaul its water system. Among the upgrades is an intake that extends farther into the lake, where blooms are less prevalent.
In the last two decades, vineyard plantings around Clear Lake have increased, supplanting the walnut and pear orchards that were the basis of Lake County’s agriculture industry. Marijuana operations, some established illegally, have also become more prominent. Fertilizers and sediment from farm runoff are a rich source of nutrients into Clear Lake, and play a role in the lake’s harmful algal blooms.
Brett writes about agriculture, energy, infrastructure, and the politics and economics of water in the United States. He also writes the Federal Water Tap, Circle of Blue’s weekly digest of U.S. government water news. He is the winner of two Society of Environmental Journalists reporting awards, one of the top honors in American environmental journalism: first place for explanatory reporting for a series on septic system pollution in the United States(2016) and third place for beat reporting in a small market (2014). He received the Sierra Club’s Distinguished Service Award in 2018. Brett lives in Seattle, where he hikes the mountains and bakes pies. Contact Brett Walton