LAKEPORT — Lake County residents either love or hate the annual infestation of aquatic weeds that occur every summer at Clear Lake and this year, because of the clearer than normal water, authorities are saying that it”s most likely there will be an explosion of weeds.
In fact, aquatic weeds are already sprouting to the surface in many areas. The reason the weeds have grown so fast is because the clear water allows the sun to penetrate to the bottom of the lake. That along with a rich nutrient supply will cause phenomenal weed growth. It”s similar to what happens in a garden; sun plus nutrients results in rapid weed growth.
Many fishermen like the weeds because they provide cover for the bass and other game fish. However, most lakeside homeowners hate the weeds because they block access to the lake for their boats and are an obstacle to swimming and water skiing.
Clear Lake has more than 50 different species of aquatic weeds. Some are native and others are introduced. The most common weeds are sago pondweed, coontail and primrose. However this year there is another species of weed that”s becoming abundant on the lake and is actually becoming a nuisance. It is a floating weed that is often mistakenly called “duck weed.” Actually the scientific name for it is Azolla filiculoides but the more common name is Pacific Mosquito Fern. It is a floating aquatic fern that spreads by stem fragments and spores. It can grow up to 2 inches long, but can be as small as one-quarter to one-half inches. It starts out a pea green color but turns reddish-purple. The plant is free floating, meaning that its roots are suspended in the water. The leaves are a host to blue-green algae and are able to convert nitrogen from the air to a form that the fern can utilize. It also receives other nutrients from the water and combined with sunlight can grow extremely fast. This rapid growth is already blocking some channels around the lake and could result in impeding boat travel. Areas such as the Clearlake Oaks Keys, Holiday Harbor, the Lagoons at Lakeport are all vulnerable to infestation of the plant. In fact, Catfish Slough (located near the Konocti Vista Casino) is already blocked by the fern. The same condition exists at Holiday Harbor in Nice.
Mosquito fern is not considered an invasive weed and in many areas it is considered as a valuable food source for waterfowl and it also supplies cover for the fish. At Clear Lake the problem is that it grows so thick that it can block water channels and even be sucked into the water intakes of outboard motors.
Eradicating Mosquito Fern can be done with a herbicide or by mechanically harvesting. Herbicide treatments have only limited success and most of the experts recommend physically removing the floating plants.
Either method requires a special permit from the county. According to Carolyn Ruttan of the Lake County Water Resources Department, anyone wanting to remove the fern from their channel or around their docks can contact her office and request a permit. Ruttan says that her main concern is how the property owner will dispose the weeds once they are gathered up. She said that she will work with lakeside property owners on how to control the spread of the plant. If the county determines that there is no danger of spreading the plant hydrilla a permit will issued. The cost of the permit is $27. For more information call Ruttan at 263-2344.
