The recent public health warnings on the blue-green algae blooms in the south end of the lake could impact tourism and even the fishing on Clear Lake. In fact, the county has posted health warnings at several locations in areas where the algae blooms are the worst.
The reason the algae is so thick in the south end and mostly absent in the north end is because the prevailing westerly winds are pushing the algae south. However, algae is now starting to form in some areas north of Lakeport.
Algae are tiny water plants that cycle normally between the bottom and the surface, floating up and sinking down. During the day, algae produces oxygen within the lake, but at night algae consumes oxygen. Algae is nothing new to longtime Lake County residents, 20 years ago the algae was so thick at times that you could hardly run a boat through it. The Clearlake Oaks Keys Homeowners Association even rigged pontoon boats with water pumps and to break up the algae mats.
Clear Lake has more than 130 species of algae. Some types actually provide food for the aquatic creatures in the lake, while others can be toxic and do more harm than good. Normally algae won”t present a problem, however, when it dies and starts to decay it can become a nuisance. The decaying algae bonds together in mats and creates a terrible odor. That”s also the time when it can become toxic.
The worst algae is blue-green (cyanbactria). There are three species of blue-green algae that can create problems under certain conditions. Blue-green algae typically blooms twice a year ? in spring and late summer. The intensity of the blooms varies from year to year, and is unpredictable. The problem occurs when algae blooms are trapped at the surface and die. When this occurs, unsightly slicks and odors can be produced. The recent algae bloom occurring in the south end of the lake has been identified as lyngbya. This type of algae can cause a number of problems. Swimmers itch is sometimes blamed on lyngbya. It can also cause health problems for animals drinking the water.
Many people mistakenly think that because the lake has large algae blooms it is polluted. In fact, the recent algae bloom near Redbud Park in Clearlake started rumors that raw sewage was being dumped into the lake. Not true. The algae blooms weren”t caused by sewage or any other kind of pollution. A lower-than-normal lake level and hot sunny days are the probable cause.
Many years ago, when many of the lakeside residents had septic tanks, there was tainted water flowing into the lake and it did result in algae blooms. But now all lakeside homes are on sewer systems and it”s very rare to have any sewage spill into the lake.
Decaying algae can be detrimental to the various species of fish in the lake. As the algae decays it uses up the available dissolved oxygen (DO) in the water, which in turn kills the fish. This is especially true of the juvenile bass and crappie. The adult fish normally swim out to better water but the young ones often stay and die.
Getting rid of the algae mats can be a problem. One of the most efficient methods is to aerate the water around the mats. This is often done using high-pressure hoses, which break up the mats. In cases where the mats are so thick that water pressure doesn”t work, airboats are often used. The goal is to break up the mats into small balls of algae, which sink to the bottom.
Most of the fishermen don”t like algae, especially when it turns the water a dirty brown color. I know that I have a hard time catching a fish when the water is coffee-colored. However, others like fishing in the green algae because it attracts bass.
As the lake level drops and the daytime temperatures reach the century mark, expect more algae blooms. We have seen it before and will see it again. It”s just part of Clear Lake”s unique character.
