Invasive weed not fazed by ‘Weed Bee’ water pumps

Water circulators designed to eliminate a problem weed from the Tahoe Keys Marina don’t appear to work.

Four solar-powered machines, called SolarBees, have been anchored in the Tahoe Keys Marina since last spring in an effort to slow or eliminate the growth of Eurasian water milfoil. But since the machines were installed, the invasive weed has continued to grow.

“The growth seemed to be little more intense this year,” said Richard Horton, co-owner of the Tahoe Keys Marina. “I can’t see any (change), unhappily.”

Growth was more intense because the lake is low and direct sunlight helps the water milfoil flourish. The reason the SolarBees had no noticeable impact is because they were put in the water in the spring instead of the fall, said Sandy Walker, a SolarBee saleswoman based out of Sacramento.

“Removing nutrients and sediment from the water column before they go dormant is what is important. That is the time when they are uptaking the nutrients,” Walker said. “Come spring we think we’ll not see 100 disappearance of the water milfoil, but a significant difference.”

Walker said the machines have reduced the amount of blue-green algae in the marina and made its water clearer.

“First you get better water quality and then you have an impact on the milfoil,” Walker said.

The SolarBees are being rented to the marina for about $15,000 to help eliminate the water milfoil, a weed likely brought into the Lake Tahoe Basin by a boat in the 1960s. SolarBee agreed to rent and not sell the machines to the marina because it sees Tahoe as a unique testing ground. The latest model SolarBee costs about $40,000.

Most marinas around Lake Tahoe battle the water milfoil each summer. The Tahoe Keys Property Owners Association is hoping the SolarBee test at the marina will prove effective.

The property owners association spends about $350,000 a year mowing the plant in its channels, the marina and Tahoe Keys Beach & Harbor Association.

“The cost goes up a little bit every year,” said Greg Trischler, manager of the water department for the property owners association. “Dump fees go up. Fuel costs go up.”

Trischler said that last week his department shut down its water milfoil harvesting for the year because it ran of money to pay for the work. The budget problem stemmed from the department’s use of its new $125,000 harvester. It doubled the amount of water milfoil cut from the lake each day, and as a result, increased dump fees required to dispose of the plant, Trischler said.

Typically the water milfoil harvesting season runs from May to October. The work requires four harvesters, three boats and a staff of 12 that goes five days a week.

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