Making lakes healthy will take lots of work

WORTHINGTON, Minn -- A drawdown on Lake Ocheda would do so much to improve the health of the lake that the rural Worthington water body could be removed from the state's list of impaired waters, Okabena-Ocheda Watershed District Administrator Dan...

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Minnesota West CTC ag students launch one of six floating biohavens Tuesday morning on Sunset Bay in Worthington. The six islands join six others launched last spring in the bay. The biohavens, containing grasses, forbs and sedges, help to filter nutrients from the water. Submitted Photo

WORTHINGTON, Minn - A drawdown on Lake Ocheda would do so much to improve the health of the lake that the rural Worthington water body could be removed from the state’s list of impaired waters, Okabena-Ocheda Watershed District Administrator Dan Livdahl said Tuesday.

The data was gleaned from information in a draft Total Maximum Daily Load (TMDL) report presented to watershed managers during their meeting Tuesday.

The TMDL study provides information on allowable phosphorus levels on both a daily and annual basis.

“(It shows) what the lake can handle without being impaired,” Livdahl said. “You want to get down to that maximum daily load.”

On Lake Okabena, the existing phosphorus load is 6,810 pounds per year - more than double the maximum allowable load of 3,079 pounds.


Meanwhile, the west basin of Lake Ocheda has a total phosphorus load of 22,156 pounds per year - three times more than the allowable amount of phosphorus loading of 7,412 pounds.

Lake Bella’s phosphorus load of 13,397 pounds per year is also more than double the maximum allowable load of 6,224 pounds.

Livdahl said the numbers in the draft TMDL are based on 2014 water testing in Lake Okabena and “the modeling for Lake Okabena is probably pretty good.” He said the data for lakes Ocheda and Bella isn’t as extensive, and those numbers may change slightly in the final TMDL report.

The numbers provided in the draft report about the three Nobles County lakes, said Livdahl, show that voluntary Best Management Practices (BMPs) need to occur.

For Lake Okabena improvement, he said, it will probably take some upgrades to the stormwater pond to remove more phosphorus before water reaches the lake, as well as upgrades to the city’s storm sewer system.

“With any development the school district may be doing on its new land, you’d be removing phosphorus there as well,” Livdahl said, adding that proposed work on the former Prairie View Golf Links property would remove approximately 1,200 pounds of phosphorus per year.

“The point is, the golf course project would get you 25 percent of the way there - it’s not going to be one project that gets you there (to goal),” he said. “It’s going to have to be watershed district-wide.”

At Lake Ocheda, reducing phosphorus loading means getting rid of the carp and establishing vegetation, Livdahl said.


“Almost all of the reduction needed can be done with a drawdown on Lake Ocheda,” he shared. “Basically, it’s west Ocheda that’s impaired. Most of the pollution is coming from the bottom of the other lakes.

“You can pretty much bring Ocheda into a non-impaired state by doing a drawdown - that’s my interpretation,” he added.

Livdahl said the final numbers in the TMDL should be published by late July.

In other business, the board:

  • Learned the E.O. Olson Trust awarded $30,000 toward the city’s redevelopment of the former Prairie View Golf Links north of Worthington. The proposed projects on the land will improve water quality by filtering out sediment and nutrients before the water reaches Lake Okabena. In addition, the trust awarded the watershed district $4,500 for the purchase of three new floating biohavens in Worthington’s Sunset Bay. The three islands, along with one purchased by the Lake Okabena Improvement Association and two purchased by the watershed district, join six others in the bay.
  • Received recommendations from the watershed district’s advisory committee on existing cost-share and incentive programs. Livdahl suggested board members give thought to the recommendations and plan to discuss the subject at the June 7 meeting, as some farmers will likely begin signing up for the Conservation Reserve Program in July.
  • Approved a stormwater pollution prevention plan for Yellow Company, LLC during the demolition and redevelopment of the former Northland Mall property.
  • Discussed plans to partner with the city of Worthington to develop a rain garden in conjunction with a community garden on a tax-forfeited parcel near the intersection of Eighth Avenue and Eighth Street.


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