One thing about living near Clear Lake is that there is never a dull moment. One week a bass tournament is canceled and the tournament director jailed, then there is a mussel invasion scare, and to top it off, the noxious weed hydrilla is back.
The bass tournament event seems to have resolved itself and as far as we know, the mussels haven”t arrived yet, but the return of hydrilla is very real. It”s the hydrilla that has most of the authorities concerned. Hydrilla was first found in Clear Lake in 1994. The state responded swiftly and kept it in check. In fact, not a single hydrilla plant was found in the lake in 2004. Even during the past few years, only an occasional plant has been found. That all changed this month when state hydrilla crews from the California Department of Food and Agriculture (CDFA) found hydrilla growing in the lake once again.
According to Les Huber, who heads up the CDFA Clear Lake hydrilla crew, a large patch of hydrilla was found in Soda Bay and the plants also were found north of Lakeport.
“We plan on treating approximately 55 acres of hydrilla in Soda Bay this week,” Huber said.
According to Huber, the crew will use a two-prong approach to get rid of the hydrilla. First they will spray the plants with the herbicide Komeen, which will knock down the plant, and then they will apply the herbicide Sonar to kill the roots.
Komeen is a copper-based chemical and has been tested by scientists at U.C. Davis and found to be safe in drinking water. It kills a plant by basically knocking it down. However, it doesn”t kill the roots. The best part about Komeen is that it acts quickly. The herbicide is sprayed on the plants and has a purple color.
Sonar is applied a few days after Komeen. It is a systemic type of herbicide, much like Round Up (which is used to kill weeks around homes). It disrupts the plant”s ability to photosynthesize. However, it doesn”t always kills the roots and tubers. Sonar acts much slower and takes longer to be effective. It is applied in clay pellets to the base of the plant. As the pellets dissolve, the herbicide kills the roots.
Both chemicals are registered and approved for use on aquatic weeds in potable water systems.
In past years, fishermen were concerned that spraying for hydrilla would kill fish, but in an experiment done in 1995, the Department of Fish and Game (DFG) placed bass, catfish, crappie and bluegill in cages and the cages were sunk in known hydrilla areas. The hydrilla crew then treated the area, including the cages, with both Komeen and Sonar. The fish were monitored for two weeks and the result was that none of the fish died or got sick. Huber said the herbicides are in such low doses that it has no effect on the fish or other aquatic creatures.
Huber also said that prior to spraying any area, water and air temperatures are taken as well as dissolved oxygen (DO) readings. If it”s too hot or the DO is too low, then spraying is delayed.
If left unchecked, the hydrilla could have a devastating impact on the lake. Hydrilla grows extremely fast and it can literally take over a body of water within a very short time.
“If not controlled the hydrilla would completely take over Clear Lake and it would become little more than a giant green field with no open water,” Huber said. “Some of the fishermen say to leave the hydrilla alone because it would improve fishing, actually it would do just the opposite and within a couple of years there would be no fish in Clear Lake,” he added.
The other big fear is that the hydrilla would pass over the Cache Creek Dam and end up in the Delta. Cache Creek empties into the Delta. Experts say if that happens, it could cost millions of dollars because the hydrilla would clog up pumps that are used for irrigation and by municipal water works.
According to Huber, September is when the hydrilla tubers will start to sprout and it”s also the month when the hydrilla eradication teams will be the most active.
Huber said he also needs the public”s support. If anyone sees what they think is hydrilla, call him at 263-1649 and report it. Teams will be dispatched immediately to check out the area. Huber said that even if it”s a false alarm, it”s better to be safe than sorry. Hydrilla is normally a bright green color with long stems, and the stalks having small whorls.
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