RINDGE — As communities around the state work to stem the spread of the invasive plant known as variable milfoil, a group of concerned Rindge residents are diving in to help get rid of the weed in Contoocook Lake.

And getting their hands dirty — and wet — in the process.

Since the beginning of June, the Contoocook Lake Area Preservation Association has been sending divers into the lake every Wednesday to manually remove the stubborn milfoil.

The lake has had 25 of its 150 acres treated with chemicals to eliminate the milfoil, but this method cannot be applied to all affected areas. Now divers are going through 10 acres of water to remove the plants by hand.

A few tenders in kayaks patrol the surface of the lake to scoop up any loose milfoil and deliver full bags to the boat where the plant is being collected. Their job is important because small fragments of milfoil can turn into new plants.

“Take a motorboat through it, you have 100,000 plants waiting to grow,” said diver Ted Aldrich of Marlow.

Aldrich is a master dive instructor who teaches a class that trains other weed control divers. He said that the milfoil plants need to be pulled from the root to ensure they will not grow back. He said that seeds from the flowers can last up to four years dormant and it can take two to three minutes to harvest a single plant.

According to an online report from Andrea LaMoreaux, N.H. Lakes Education Director, there are six native milfoil species present in New Hampshire that do not cause problems. However, variable milfoil comes from a different region and thrives in New Hampshire’s acidic water without predators.

The plant, which according to the association’s website looks like a green cat’s tail with a reddish stem, can disrupt the ecological balance of water bodies and make recreation dangerous.

“It snuffs out all of the native plants,” said Aldrich. “You can’t swim in it, can’t paddle in it; it looks like you can walk across.”

Ted Covert, the Contoocook Lake Area Preservation Association’s president, said that the plants wrap around boat propellers and are a chore to remove. The propellers also cut the milfoil, which can then spread it further into the water.

“It fills the entire lake,” he said

Three divers and eight tenders are involved with the cleaning. They can retrieve more than 70 gallons of milfoil in one trip, which usually lasts seven to eight hours.

This week Covert went with three divers and two tenders to Jowders Cove, which was especially thick with milfoil. Residents like Bill Fisher, who lives next to the affected area, are happy to see the effort to clean up the lake.

“Its the only solution really, there is no other way to do it,” Fisher said.

According to Covert, the divers will work on removing the milfoil until the amount retrieved is decreased, which he estimates will take about six to eight more dives.

Boaters can help maintain the spread of variable milfoil by cleaning any aquatic transportation before entering or leaving any water body and avoiding any areas with weed patches.

For more information on the Contoocook Lake Area Preservation Association, visit www.contoocooklake.com.