WAHIAWA, Oahu -- The federal government calls it one of the world's worst weeds, and it is beginning to take over Lake Wilson in Wahiawa.

The plant looks pretty until you realize that the fast-growing salvinia molesta is a potential killer, KITV 4 News reported.

"It cuts off sunlight to the lake, it cuts off oxygen to the lake. The whole lake goes anoxic (deficient of oxygen). Basically it kills the lake," said Bob Bourke, biologist for Oceanit Inc.

Although it's been banned, the Brazilian water fern is still popular in aquariums and garden ponds. That's probably how it got into Lake Wilson, according to officials.

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Lake Wilson Plant Invasion

"It goes down the gutter, into the stream and then into the reservoir and then it starts growing and it grows really, really fast," Bourke said.

State biologists noticed it several years ago, but said the recent explosive growth began just a few months ago.

The plants are fertilized by a county sewage outfall and encouraged by stable water levels. The growth of the infestation doubles in size every few days.

The state and county will begin trying to scoop out as much as they can Wednesday.

"Whether that'll be able to eradicate it off the lake is quite doubtful," Bourke said.

The weed breaks into small pieces, any one of which can start a whole new colony.

The state hopes scooping up the salvinia will work. The other choices -- chemicals or a weed-eating Brazilian bug -- pose their own environmental risks.

This is not the first time Lake Wilson has been overgrown with water plants.

In 1997, the state used a boat with a "pusher" to remove water hyacinths that were strangling parts of the lake.

The state said that water plant has been pretty much eradicated because it's bigger and easier to collect than the salvinia molesta.