The Kingsbury County Commission really wants to pull the plug on Lake Thompson, or at least on the top few feet of water that has been devouring shoreline and sitting on roads all year. There is an outlet in Miner County that we could knock out to drain the highly variable lake, but downstream counties aren’t exactly eager to try that, and the state won’t allow it.
So Kingsbury County asked the state Board of Water Management if they could just mow and dredge down by the outlet so the water could flow out more easily:
Consulting engineer Jason Petersen had outlined three options for getting water flowing faster out of the swollen lake and down the East Fork of the Vermillion River:
Removing 400 feet of vegetation — mostly cattails — from each side of the 48-foot outlet that feeds into the river; or
Removing sediment from a 50-feet wide channel covering the same stretches; or
Bringing in a boat that could cut weeds a half-mile up the 12-mile-long lake and dredge some of the bottom [Bob Mercer, “Kingsbury County Gets Sort of a Green Light for ‘Maintenance’ at Lake Thompson from S.D. Board,” KELO-TV, 2019.09.11].
Interestingly, in its August 21 filing with the board, Kingsbury County says that engineer Petersen says that removing cattails and sediment “would have minimal impact on reducing the lake’s water level.” But they’d rather do something than nothing, given the record water levels.
Here’s a chart from Petersen’s report showing Lake Thompson’s dramatic rise in water level from 1984 to 1988 and then the varying high levels through 2013:
A subsequent attachment to Petersen’s report cites Thompson water levels from May through July of 1,697 to 1,698 feet.
Mercer reports the board heard over three hours of testimony on the issue, then actually spent over half an hour in closed session with their attorney. I know discussions about potential legal action are one of the excuses for closing the doors… but really? We’re talking about a matter of great public importance, involving action by various public bodies—can we really justify putting any of that conversation behind closed doors?
The Board of Water Management appears to have mostly passed the buck, telling Kingsbury County they can do their plan but only if they run it by the Department of Environment and Natural Resources first.
Decisions behind closed doors, the South Dakota way.
The Lake Thompson problem will never be solved. First of all the outlet for the lake has not changed and the lake has not set a new high water level. Those lake dwellers should have done their homework before they built on the shores. If they decided to try to lower the level of the lake they will completely flood Montrose and the lawsuits would never end. The first thing they need to do is stop the drainage from ditching and tiling in Lake County which has made this a bigger problem than it was in years past.
Greg, are you saying that the ditching and tiling in Lake County has reduced the capacity for the areas downstream of Thompson for additional flows? Nothing in Lake County flows back to Thompson, does it?
Greg, how many homes have been built along Thompson since the 1980s water surge? I would certainly agree that homes built in the past couple decades near the new high water mark are taking a great risk building on land that could be easily saturated and eroded.
No Cory, I am saying that the drainage going into the Lake Thompson is causing the problem. There are hundreds of miles of tile from Lake county that are drained into Lake Whitewood which drains into Lake Thompson. Whenever you put drain tile in it moves water off your land on to someone else. These lakes in Kingsbury County cannot handle anymore drainage. There has probably more than 50 new lake homes that have been built since 1986. If people want to build lake homes on Lake Thompson they should do some research. The overflow outlet on Lake Thompson has not changed since 1986.
Dang! Water runs north up there? Interesting! Where’s the watershed cut-off? Even up to Ramona, water runs south or west into the Vermillion River, doesn’t it?
Since you brought it up, I highly recommend the Moan Town Bar in Ramona for lunch or a steak. Tell ’em you know the boys in DenTown.