Dodge County SWCD promoting Rain Gardens in county

You have probably noticed them in commercial areas and on lawns. Usually small depressions in the landscape filled with a variety of flowers and plants.
They’re rain gardens and they serve a purpose beyond aesthetics. They help in allowing rainwater runoff from areas like roofs, driveways, sidewalks, parking lots and compacted lawn areas to be absorbed and soak back into the ground instead of flowing into storm drains and surface waters.
They are part of the effort to reduce erosion, water pollution, flooding and damage to groundwater.
The Dodge County Soil and Water Conservation District and the Zumbro Watershed Partnership have been holding a series of rain garden sessions throughout the county with Blaine Delzer of the Dodge SWCD and Zumbro Water District Board Member Jim Hruska explaining the concept and his experience with rain gardens.
These sessions, Hruska said, are not to give detailed instructions on how to build a rain garden but rather an overview of what a rain garden is, a basic idea of how to build one and information on where to look for detailed information.
“Protecting the soil and the water is my passion,” Hruska told a group of interested residents last week in Mantorville.
Most of Dodge County lies within the Zumbro Watershed, he said, with smaller portions in the Cedar or Root River Watersheds. Dodge County, he said, is at the top of the watershed so the people downstream “see how we treat our water.”
Rain gardens, Hruska said, have a variety of benefits.
They soak up 30 percent more runoff than lawns, help filter polluted water, recharge groundwater, help prevent flooding, create habitats for wildlife, reduce the pressures on existing stormwater infrastructure and improve water quality. Plus, they beautify the landscape.
“They are a nice way of cleaning up a lot of our water,” Hruska said.
Although the larger a rain garden is the more water it can filter, they do not have to be large, he said. 
“Whatever you can handle is great,” he said. “You’re doing something.”
When designing a rain garden location is important, Hruska said.
For starters they should be at least 10 feet from the house, he said, to allow room for runoff from the roof to flow to the rain garden. They also should not be built over buried utilities or where the mature plants could interfere with overhead utilities.
Depth of the rain garden is more important than size, he said, so the first step is to determine how fast the water soaks into the ground. Once this has been done a shallow depression is dug with the center depth about equal to the infiltration rate with shallower sides.
The water source, which may be downspouts or sump pump outlets will need to be connected to the rain garden either with an underground pipe or a dry creek bed created by digging a shallow, rock-lined trench to the rain garden.