An engineering company has recommended that Lake Mitchell be dredged to deal with its longtime and increasing algae problem. The Mitchell City Council heard a presentation from Barr Engineering at Monday’s meeting. Dredging the lake would cost around $25 million according to Eric Lund, who is an engineer with Barr.
“The dredging, you’re gonna pay for how much sediment you take out of the lake,” Barr told the council. “So the volume or the thickness is really important, as well as where you are on the lake. It’s driven by the cost of diesel and how far you have to move the sediment.” He added that they were looking at 10 to 25 dollars per yard for dredging. The preliminary engineering report rate was 12 dollars per yard, but that was closer to the disposal site. Lund told the council that dredging the lake would remove around 70 percent of the surface area sediment. The sediment would be disposed of at Firesteel Park on the west side of Lake Mitchell.
Another lake improvement plan discussed would involve alum treatments. That would cost around $16.5 million according to Lund.
“On the alum side, the volume is not important, it’s the area,” he said. “You’re treating the lake bed, and so if you have one foot of sediment or ten feet of sediment, you’re applying the same dosing. So there are different characteristics that affect the cost for these different technologies.”
Lund told the council that regardless of how they decide to treat the lake, a long-term plan for the Firesteel watershed was needed. A decision by the council on Lake Mitchell is expected to be made this summer.