Group targets weed
choking Lake Wilson

Gov. Lingle's support is sought
in an effort to rein in the plant

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By Diana Leone
dleone@starbulletin.com

A group of government and private officials worried about a weed choking the life out of Lake Wilson plans to ask Gov. Linda Lingle today for support.

Senate President Robert Bunda (D, Wahiawa-Waimea) said he hopes the governor can declare a state of emergency or focus resources on reducing the amount of Salvinia molesta that is now covering 90 percent of the 300-acre lake.

Over the last two weeks, Bunda's office hosted a gathering of officials with the state departments of Land & Natural Resources and Agriculture, the U.S. Department of Agriculture, Fish and Wildlife Service, Army, Army Corps of Engineers and Dole Food Co., as well as City Councilman Donovan Dela Cruz, state Rep. Marcus Oshiro (D, Wahiawa) and representatives from Hawaii's congressional delegation.

Out of those meetings is emerging a plan to reduce the plant's coverage on the lake's surface to 10 percent by July, said Bill Devick, administrator of the Division of Aquatic Resources. That will take some increased intensity.

"It's expanding like mad," said Devick, who estimated that coverage of the lake has tripled since November, despite the fact that city and state crews removed 1,000 cubic yards of the weed in November and December. The battle was waged with Environmental Protection Agency-approved herbicide in January because the proper equipment and access were not available to continue mechanical removal.

One estimate of how much plant growth would need to be removed was 500,000 cubic yards, or 500 times what has been removed so far, said Bunda administrative assistant Laura Figueira.

"It's imperative to get ahead of the problem as soon as possible" to prevent a massive fish die-off from lack of oxygen in the water, Devick said. Lake Wilson holds an estimated 300 tons of fish, and as the weather heats up, the amount of dissolved oxygen will go down unless more surface area is cleared, he said.

Army Corps of Engineers specialists will be on Oahu this month to provide technical assistance based on successful mainland infestation removals, said Derek Chow, a Corps senior project manager.

For the longer term, a South American weevil (Crytobagous salvinae) that eats salvinia could be a solution, said Susan McCombs, director of the USDA's Hawaii Plant Protection Lab in Waimanalo. The bug has worked "very well" reducing salvinia infestations in Texas and Louisiana, she said.

It will take months to years of experiments to make sure the foreign weevil does not also chow down on native plants before it could be approved for import as a way to control salvinia.

In the meantime, resources are being pooled despite budget constraints.

DEAN SENSUI / DSENSUI@STARBULLETIN.COM A small weed, Salvinia molesta, has infested Lake Wilson and so far has survived efforts to eradicate it.