NEW AUBURN — As the spring rains fall, the rain gardens of New Auburn are doing what they are intended to do: hold back and filter water before it flows into streams and lakes.

“They work fantastic,” said Kelly Wuetherich, who along with his wife, Deb, own a farm along nearby High Island Lake and who are leaders in improving the lake.

Rather than installing expensive curb and gutter along the streets in the small town and collecting storm water in retention ponds, volunteers have been installing rain gardens to hold most rain water until it soaks back into the ground, and at least filters the water during heavy rains when some does flow into storm tiles.

Wuetherich said checks on the gardens last fall showed them working well. After a nearly 2-inch rain one night, he checked down a manhole next to one of the rain gardens and saw no evidence that any water had flowed past the water garden.

“There could have been some that went into the tile overnight, but it looked very dry. It stopped most if not all of the water from running off and let it soak into the ground.”

The group will be installing two more rain gardens this spring and then will be able to do scientific studies on the water quality and amount of water in a tile line along a rain garden route compared to another without rain gardens.

Meanwhile, a drawdown of High Island Lake is continuing. The shallow lake is about 2 feet lower than it was last fall after a control structure was opened to allow water out. Wuetherich, with the guidance of the Department of Natural Resources, is monitoring the drawdown.

The aim is to expose some bottom mud to the sun, kill some algae and rough fish, stimulate the growth of submergent vegetation and allow the lake to naturally refill. If all goes well, the DNR plans to stock some game fish in the lake, possibly next year.

They had hoped for a winter kill of rough fish, but Wuetherich said conditions weren’t right and the lake wasn’t low enough for a good kill off. After the lake is lowered as much as possible this summer, they are hoping for more success next winter in getting rid of rough fish, which stir up the mud and rut out beneficial submergent vegetation.

The 1,600-acre lake has an average depth of more than 5 feet, with deep spots close to 10 feet.

The Wuetherichs are leaders of the Friends of High Island Lake group. They said they’ve watched the lake deteriorate significantly during the past 15 years.

The town of just more than 500 residents sits at the west edge of the lake. The community created a master plan on where the rain gardens should go. As part of a grant New Auburn received to build a water tower, engineering firm Bolton & Menk figured out the best place to install 40 rain gardens around town.

Several communities, including Mankato, have installed some rain gardens to help clean water naturally. But few have goals for such a complete system of gardens as does New Auburn.

Rainwater gardens are relatively small areas of plantings in ditches, near drain spouts, or at other areas where runoff water is plentiful after rains.

The gardens are created by digging a trench nearly 6 feet deep and adding sand, small stones, soil and organic mulch, which lets the water settle into the depression.

Hardy native species are planted, including grasses with deep root systems.

They are designed with a tile line running along the bottom of the trench so water does not stand more than 48 hours to prevent mosquitoes from breeding.

The gardens serve as micro-retention ponds, filtering out pollutants and lawn chemicals.