September 2, 2011 in Idaho

Floating wetlands clear inspiration

By The Spokesman-Review
 
Jesse Tinsley photoBuy this photo

Volunteers Todd Walker, left, and Christy Latta dress a floating mat in grasses, sedges, reeds and other vegetation to produce a floating wetland on Thursday near Hayden Lake. The floating island of vegetation will soak up excess nutrients in this farm pond as a proof-of-concept project with Kootenai Environmental Alliance organizers.
(Full-size photo)

On the Web

Watch a video about the project and how a floating wetland is constructed at spokesman.com/video.

Rafts made out of plastic membranes, sprouting cattails and other nutrient-loving plants could help solve Hayden Lake’s water-quality problems by soaking up excess phosphorus. Karen Hayes can picture a flotilla of them on the lake she loves, simply and ingeniously cleansing the water.

“A lot of people who live on the lake come here to kick back,” said Hayes, a resident of the lake’s east shore. “The last thing they want is a science lesson or someone wagging a finger in their face.”

But if lake residents could convert their docks into “floating wetlands” that would filter nutrients, acting like a set of kidneys for Hayden Lake and improving water clarity and reducing the aquatic vegetation so many boaters find noxious, she thinks the idea could take off.

Hayes is part of Kootenai Environmental Alliance’s Hayden Lake Project, which is working to improve the lake’s water quality. The organization recently received a $5,000 private grant to test the floating wetland idea.

The technology is getting a trial run on a 1-acre pond on Hayes’ property. Volunteers turned out Thursday to plant the 200-square foot raft with cattails and other wetland vegetation. Over the next year, the pond will be tested for total phosphorus, dissolved oxygen and water clarity.

If water quality improves, Kootenai Environmental Alliance will look for ways to expand the floating wetlands to Hayden Lake, including cost-share programs for property owners, said Adrienne Cronebaugh, a KEA conservation associate.

Since 1998, Hayden Lake has exceeded federal water-quality standards for phosphorus. Barbara Mueller, who lives at Sandbar Point on the lake, said she sees the effects of nutrient loading, including a gradual change in the lake color.

“When we first moved in, it was bluer. Now, it’s greenish,” said Mueller, who has spent more than two decades photographing the lake.

Mueller and her husband and their neighbors installed new septic systems to reduce phosphorus flowing into a nearby bay. But they’re still seeing declines in water quality, including algae growth and reduced water clarity, she said. Nutrients enter the lake through multiple sources, including erosion, fertilizers and runoff from residential developments.

“It’s hard to battle it,” Mueller said of nutrient loading in the lake, “because it’s happening faster than anything we can change.”

Mueller attended Thursday’s work party to learn more about the floating wetlands, which she hopes could provide a partial solution.

The rafts are made by Floating Island International, a Montana company that has shipped more than 4,000 worldwide. In some trials, phosphorus levels in water bodies have dropped by as much as 40 percent, Hayes said. Testing will reveal if those results can be duplicated in North Idaho’s short growing season.

The raft KEA ordered is made out of spongy, recycled plastic. Within a couple of hours, the volunteers had planted cattails, sedges, rushes, grass and wildflowers on the raft, which acts like a membrane. The roots will dangle out the bottom, forming a thick mat that will suck nutrients out of the water.

Because the vegetation is above the waterline, it won’t release phosphorus back into the lake when it dies back, Hayes said.

“I can’t wait to see this thing next spring,” said Andy Kemp, who moved to McLean Bay on the lake about three years ago. Before then, “I’d lived in subdivisions all my life,” he said. “I didn’t think about lakes and streams, because it was all concrete.”

If the pilot is successful, Kemp said he hopes to see the floating wetlands catch on. Instead of growing potted geraniums on their decks, Hayden Lake residents could grow native plants in floating flower boxes, he said.

“Whatever we have to do to get the lake water cleaned up, I’m all for it,” Kemp said.


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