A wetland that for years kept pollutants from reaching Lake Ida is itself so polluted that local officials are proposing to steer running water around the wetlands on its way to the lake.
Wetlands are supposed to act as a filter for running water, sifting out soil particles that contains phosphorus and other pollutants before they reach lakes. However, local officials were puzzled a couple years ago when tests showed that the water coming out of the Lake Ida wetland in the summer was more polluted with phosphorus than the water entering it.
Following more tests and an engineering study, one local official said he still is not sure what has caused water to become more polluted once it goes through the wetland.
“This may be a natural condition in this kind of wetland,” said Jerry Haggenmiller, coordinator of the Douglas Soil and Water Conservation District. “Nobody can say for sure it wasn’t in the same condition in 1910.”
Runoff from farm fields and lawns may also be culprits since fertilizers often contain phosphorus. Naturally-occurring phosphorus is scarce in western Minnesota, state agencies say. A ditch running nearly 12 miles from Garfield drains cropland and developed land, ending up at the Lake Ida wetlands.
Whatever the cause, officials say they want to keep Lake Ida – one of the county’s biggest, deepest lakes – from becoming filled with algae blooms.
“The whole community wants to keep the lake clean,” said Mike Cleary, a conservation district board member. “The lakes are a big draw for tourists and without tourism the city of Alexandria would not be as vibrant and prosperous as it is.”
At an Aug. 12 meeting, the Soil and Water Conservation District board gave staff permission to seek a $750,000 grant from the state to bypass the wetland and to take other measures to keep phosphorus from seeping into the lake. They will seek additional funding to help farmers and other landowners make property changes that will help Lake Ida.
“I’m happy they decided to do something,” said Dick Sudmeier, president of the Ida Lake Association. “It sounds like the project will definitely help the lake situation.”
However, the board has taken some fire from Steve Henry, president of the Douglas County Lakes Association, who said its plan hasn’t been aired thoroughly enough. The engineers who studied Lake Ida and Ditch 23 that drains farm fields have not been made available for public questions, he said. He would like the district to post its plans online, as has been done in other counties.
“For a project of this size, there should be more public input,” he said.
Cleary and Haggenmiller said that the engineers haven’t completed their study, but that they will meet with members of the Ida Lake Association when the study is completed.
The district is moving ahead with its grant proposal because of a Sept. 9 deadline, they said.
Although Lake Ida has been close to becoming impaired, engineers said it’s doing surprisingly well, considering all the farm fields that surround it, Haggenmiller said.
“What they told us was for ag watershed, this was pretty good,” he said.
Barr Engineering recommended two major steps:
Build the ditch along the northern edge of the wetland. The ditch will follow a winding path, and those bends will slow the water speed so that it can lose much of the phosphorus-containing soil it carries before entering the lake.
Replace a malfunctioning weir. The weir is supposed to channel ditchwater into a U-shaped basin where it can deposit sediment before continuing back on its path to the lake. However, it has sunk down and ditch water is not getting diverted there.
Together, those two projects will cost an estimated $750,000.
Haggenmiller said he does not yet know how much those projects will reduce phosphorus going into Lake Ida.
The engineering firm also recommended action for landowners in the Lake Ida watershed. Development and wind have caused soil erosion along lakefronts. In some cases, gullies have opened up, causing more runoff into the lake, and engineers will have to reconfigure the slope of the land. In other cases, staff will ask farmers to plant cover crops after the fall harvest to keep soil from running off their land.
Landowners may also be asked to add native plants, whose deep roots can keep soil together, and farmers may be asked to alter the landscape of their land to prevent runoff.
As an incentive, the Soil and Water Conservation District is hoping to land enough grant money to cover 75 percent of the landowners’ costs.
“We can’t tell them they need to do it, but encourage them to do it,” Cleary said.