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Cleaning up the lake continues to be a hot topic

Posted on May 6, 2024

Over the past 30 years there have been a number of calls to clean up Clear Lake. If this sounds familiar it’s been a hot topic for years. Over the past 40 years there have been a number of groups that have wanted to change the lake dramatically and they range from dredging the lake to a depth of more than 100 feet to spraying the lake with a herbicide to kill the weeds and algae. Assembly bill AB 707 was passed to clean up the lake of mercury.  The mercury in the lake comes from the old mercury mine near Rattlesnake Island. It was on the Super Fund for cleanup and a lot has been done.

The bill also called for eliminating some of the aquatic weeds and algae. It’s a great idea if it can be done. The lake has had algae blooms for thousands of years. The one factor that would help is to restore the wetlands which for eons acted as a filter for the lake but many of them have disappeared in the last 50 years..

Down through the years there have been a multitude of suggestions to change Clear Lake and they range from rerouting the Eel River through Clear Lake to flush it out, to treating the lake with thousands of gallons of aluminum sulfate to rid the lake of algae and even dredging the lake to a depth of more than 100 feet. While all have sparked interest at the time, they have all failed to occur because biologists and geologists have said that the harm to environment would far outweigh the benefits.

Let’s look at the history of one of the oldest lakes in North America. Clear Lake has been a shallow lake for thousands of years. Ten years ago an organization called California Association of Lakebed Management held a three-day seminar in Lake County for scientists from throughout the state. A number of the eminent scientists who had studied Clear Lake said that it  had always been considered a shallow and fertile lake. Hundreds of years ago there were some deep holes in the south end of the lake but the main body of the lake has always been less than 30 feet deep.

As for the algae, while it does present problems during the hot summer months, for most of the year the lake is relatively free of algae during the summer and winter months. Actually, some algae is good for the lake because zoo plankton feed on the algae and the fish eat the plankton. When Dr. Livingston Stone visited Clear Lake in 1872 he wrote that during the month of August the algae was so thick in some areas that you couldn’t push a boat through it and in those days very few people lived in the county. There was also little or no agriculture to create run-off into the lake.

There are more than 130 different species of algae in the lake. There are good species of algae and bad ones. Clear Lake has the highest population of fish in the nation and many of these species of native fish feed on zoo plankton which in turn feed on the algae and without these types of algae our fish population would only be a shadow of what it is now. Among plants on the lake, algae are among the least studied.

Algae are tiny water plants that cycle normally between the bottom and the surface, floating up and sinking down. During the day, algae generate oxygen within the lake and at night they consume oxygen. Algae are among the oldest living organisms on our planet, going back at least two billion years. Without question algae are the most important plants on earth. They generate more than 70 percent of the oxygen in the atmosphere and without them there would be no life on the planet.

We also have to be very careful about disturbing the bottom of the lake. There are residues of pesticides resting on the bottom like the now banned DDT and DDD that were sprayed extensively years ago on Clear Lake to get rid of the gnats.  Would these pesticides rear their ugly heads and have an effect on the fish and bird life that call Clear Lake home? Some of the biologists that I have spoken with are definitely concerned.

AB 707 benefited the county and the lake by creating a blue ribbon committee to study and protect the lake. While it’s encouraging that a local group citizens want to improve the lake, a number of scientists and biologists have told me that great care should be used before attempting to change the oldest lake in the country.


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