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Floating islands deal with odor, algae

A BioHaven floating island was towed into the pond last week. (Submitted photo)1 / 3
Aquatic plants' roots dangle into the water, growing microbes that break down phosphorus, nitrogen and other pollutants. (Submitted photo)2 / 3
Bruce Perkins of Woodbury shows off the BioHaven floating islands in the pond behind his Pendryn Hill Curve home. They are the first such ecosystem-friendly poly matrix islands in Woodbury. (Staff photo by Mathias Baden)3 / 3

Last week, the pond west of Pendryn Hill Curve in Woodbury received a boost to its ecosystem when three islands were floated and anchored into its waters.

BioHaven floating wetlands provide water filtration and cleaning functions the same as natural floating bogs. The plant roots and poly material grow microbes to break down pollutants, like phosphates and nitrates, that cause serious odor and algae issues. Microbes and algae use phosphates and nitrates as food to make proteins and other biological molecules, such as DNA, that are an integral part of the cell, said 3M Research Specialist Kannan Seshadri, a chemist.

The poly matrix, which houses the plants and keeps 25,000 water bottles out of the dump, is made of BPA-free polyethylene terephthalateplastic used for a new floating ecosystem.

It's a pilot project for a city with hundreds of ponds.

Floating Island International has launched 6,000 floating islands worldwide and 60 in Minnesota, but these are the first in Woodbury, according to Amanda Boos of St. Paul-based Midwest Floating Island.

The 1.8-acre stormwater drainage pond is a mucky, yucky water feature full of wildlife—frogs, turtles, 20 baby ducks, geese, egrets, blue heron, fish, and an occasional deer visits for a sip. While the pond was dredged last winter, duckweed and green pondweed pollute the water body.

"That's why we think it's a wonderful idea," said Bruce Perkins, whose wife proposed a freshening up of the pond. "They get their nutrients from the water and at the same time take out things."

Sharon Perkins researched the 2,000-plant floating islands and then contacted the city to purchase the structures.

It's on the residents' shoulders to make sure the islands work. For the first year, they'll grow marigolds on the islands.

Bruce said that if the marigolds wither, neighbors will know that the plants aren't getting enough water from below and they need to water the islands by hand.

Last Wednesday and Thursday, the company assembled the islands with a dozen or so workers, and Sharon volunteered to help. Once the aquatic plants' roots were dangled through 500 holes in the poly, workers towed the islands by rowboat and canoe into the middle of the pond.

The islands should add to the ambience surrounding the pond. Three islands total about 1,000 square feet, so while the islands will stay in place during winter months, they shouldn't get in the way of ice skating and hockey taking place after the pond freezes over, Bruce said.

"The floating islands in this ... pond water should create a much healthier ecosystem, clearer water and will support the extensive wildlife that frequent this pond," Sharon said. "The frogs and turtle will love these islands, too. We're thrilled with these three hardworking islands!"

Seshadri said: "I hope this spurs creation of more of these structures that provide that provide both an environmental and ecological function, as well as keep our city's water bodies beautiful."