Weed cleanup at Lake Wilson goes full throttle
| • | Map: Salvinia cleanup update |
By Catherine E. Toth
Advertiser Staff Writer
With growing recognition that the state is confronting a substantial natural threat at Lake Wilson, officials announced yesterday that more than $1 million has been dedicated to a stepped-up counter-attack against the stubborn salvinia weed.
Gregory Yamamoto • The Honolulu Advertiser
With two extraction sites now open and herbicide spraying begun, officials also said they will consider extending weekday work hours and schedule work on weekends starting next week.
A boat pulling a boom rounds up the noxious weed Salvinia molesta yesterday in Wahiawa's Lake Wilson. The state and city have each dedicated $500,000 to the stepped-up effort to clear the reservoir of the invasive weed.
Crews are now onsite from 8 a.m. to 2:30 p.m. Monday through Friday, with no work being done on weekends.
But the rapid growth rate of the noxious weed Salvinia molesta, coupled with slower-than-expected progress of extracting the plant from the lake, has prompted officials to mount a more aggressive campaign.
Yesterday they acknowledged that the immediate goal has switched from clearing the lake of salvinia to getting the weed under control.
"We're hoping to extract as much as we can in the shortest time period possible," said Eric Hirano, head of engineering for the state Department of Land and Natural Resources. "We're trying to do it in 28 working days, but it might take a little longer."
The goal is to clear between 50 percent and 70 percent of the 300-acre surface of the lake, Hirano said. Clearing areas of salvinia will allow oxygen to get into the water, keeping the estimated 500 tons of fish in the lake alive. The extracted salvinia is being dumped in fallow fields about three miles north of Wahiawa.
"Over time the lake will be cleared up, there's no question about that," said Lyle Wong, administrator for the Plant Industry Division of the state Department of Agriculture. "But we're not sure how long (it will take)."
Controlling the noxious weed from spreading in the lake — or elsewhere in the state — could become a full-time job for city and state workers, Hirano said.
"Our long-term effort is to monitor it and suppress new infestations," Hirano said. "Right now our main effort at this point is to retard the growth (of the salvinia), extract as much as we can and open enough water to save the fish."
In announcing costs for the first time yesterday, officials said more than two-thirds of a $150,000 federal grant has been spent, and the state Department of Health and the city have committed $500,000 each to fight the infestation.
Crews are extracting about two acres of salvinia a day at two sites: behind Kemo'o By The Lake condominiums on Wilikina Drive and at the Lake Wilson Recreation Area. Workers on boats are spraying about 14 acres a day with AquaMaster, a herbicide specific to aquatic weed control, at two areas in the lake away from the excavation sites.
Gregory Yamamoto • The Honolulu Advertiser
Operating from two sites, the state hopes to excavate about 20 acres of salvinia and spray an additional 50 acres every week. State officials anticipate opening a third site on a small peninsula north of the first site behind the condominiums with military support.
A dump truck unloaded salvinia weed at the Lake Wilson Recreation Area parking lot yesterday.
Yesterday the military told the state it could fully equip a third extraction site with loaders, excavators, bulldozers and dumpsters. But to get to the site, an access road will need to be built.
Details regarding the cost to open the third site have not been worked out, Hirano said.
The state is also considering bringing in an airboat to expand the area of spraying, which is the most effective way to combat the infestation, officials said. It would cost about $100,000 for a six-week airboat operation, Wong said.
Officials also said they're examining the viability of using the salvinia weevil, a proven biocontrol for salvinia. The tiny insect causes immense damage to the plant by feeding on terminal buds, which greatly reduces large infestations and stifles the weed's rapid spread. The weevils were experimentally released in Texas and Louisiana in 2001 by the U.S. Department of Agriculture.
"Our biggest concern is whether this will work or not," said Peter Young, DLNR director. "Do we create a bigger problem by bringing it in?"
The state spent about $100,000 to deal with the infestation from July to December 2002. That money came from the budget of DLNR's Aquatics Division.
But the limited effort wasn't enough, and the weed spread faster than it could be controlled.
"We did not take the aggressive action we are taking now," Young said. "Invasive species are not healthy to Hawai'i's environment, and we need to be conscious of that. We need to take immediate and aggressive action."
Meanwhile in Kailua, about 80 people showed up at a community meeting Tuesday night to hear about plans to clear the noxious weed from Kawainui Marsh.
Sen. Bob Hogue, R-24th (Kailua, Kane'ohe), said the city has been spraying the wetland with herbicide and volunteers will go in at 8 a.m. March 22 to clear the weed from the banks and waterways.
Ten teams made up of six people each were formed. The teams include a cross section of the community including teens, business leaders, school teachers, politicians and state personnel, Hogue said.
For more information about volunteering, call Hogue's office at 587-7215.
Reach Catherine E. Toth at ctoth@honoluluadvertiser.com or 535-8103.
