Add sewage spills to problems at Wahiawa's Lake Wilson

By Karen Blakeman
Advertiser Staff Writer

A city worker has been stationed at the Wahiawa Wastewater Treatment facility to monitor a faulty sensor that malfunctioned twice last week and dumped partially untreated sewage into Lake Wilson, which is already endangered by an overgrowth of noxious weed.

Carol Costa, a city spokeswoman, said the last spill on Saturday dumped 34,000 gallons of wastewater that had been processed through three preliminary treatments but had not undergone the final treatment, an ultraviolet cleansing.

An earlier spill, about a week ago, dumped 48,000 gallons of wastewater that had not been through the ultraviolet disinfection stage, she said.

Costa said that 2 million gallons of treated wastewater is processed through the man-made lake — which she said was meant to serve as an irrigation reservoir — on a daily basis. She said city workers assured her the 17-minute spill would have been diluted before it could cause damage.

The city placed signs around the lake to warn residents of the spill and notified the state Health Department, which will oversee the city's testing of the water of Lake Wilson this week for elevated bacteria levels.

Costa said the spills should not have any effect on the condition of Lake Wilson or the noxious weed Salvinia molesta, which has covered 95 percent of the lake's surface and produces as much as 400 tons of new growth each day.

Work to clear the weed was scheduled to resume today after state workers took the weekend off.

The removal effort was already falling behind schedule last week and crews planned to use a herbicide against the weed this week.

The state is using a $150,000 federal grant to finance the lake cleanup, and lawmakers are looking for alternative sources of money from city and state budgets to finance the rest of the project.

About a dozen people have been working each day to remove the salvinia.

Correction: The city is responsible for testing Lake Wilson for elevated bacteria levels after a sewage spill from the Wahiawa Wastewater Treatment facility. The state Health Department oversees the testing. A previous version of this story was incorrect.