May 6—MITCHELL — State officials have given the greenlight for a permit to keep Lake Mitchell’s spillway and dam structure at its current capacity.
On Wednesday, May 6, the South Dakota Department of Agriculture and Natural Resources Board of Water Management unanimously approved the city’s petition for a variance permit for the Lake Mitchell spillway and dam structure.
Whitney Kilts, the DANR engineer who oversees dam safety and ground and surface water permits, told the board the Houston Engineering study was consistent with Water Rights Program staff findings on Mitchell’s high hazard dam. Houston completed the study earlier this year and found the spillway and dam structure could support a 23% probable maximum flood, and could not pass the state required 50% probable maximum flood. This prompted the city to request a variance, which is allowed by state statute.
Now that the variance has been approved, separate permits for
putting a hole in the spillway, discharging water, and putting the spillway structure back together would still be need approved by the state.
These permits were
suspended in late summer 2025
and
the city plans to pick up where it left off.
Mitchell Mayor Jordan Hanson told the Mitchell Republic the fall 2026 drawdown bid is dependent on if the bids are acceptable and the contractor’s schedule. That would make 2027 the earliest the lake could be dredged, according to Hanson.
Hanson requested a checklist with set dates from Barr Engineering.
“No more unforeseen roadblocks,” Hanson said of the checklist. “I want to know everything we’re up against until the end of the project.”
Paul Muth told the water board during a public comment period that he didn’t want the water from Lake Mitchell either. Muth owns land east of Mitchell along the James River, which is downstream of Firesteel Creek.
“How can you dump your water on your neighbor’s land?” Muth said.
Kilts noted if any additional development were to take place downstream and “potentially change the risk to loss of life,” the chief engineer of the Water Rights Program would bring the variance back to the State Board of Water Management for review. If that happens, the state would evaluate if the spillway would need to be upgraded to reduce loss of life risk. Structures that could be damaged by spillway failure are in Houston’s report, which lists 18 addresses in a danger zone for a potential dam breach, including on Foster Street, First Avenue, Scenic Court and near and downstream of the James River. A danger zone is considered “when occupants of most houses are in danger from flood water” or anything above 6 feet of water.
According to Kilts, requiring the spillway to be upgraded to meet the rule would cause increased risk of damage to downstream residents, even without a dam failure.
“At the current level of downstream development, there is a case for a variance to allow the current spillway capacity to be maintained,” Kilts said.
Adam Mathiowetz, the acting chief engineer of DANR’s Water Rights Program, recommended in March the Water Management Board grant the variance with qualifications, “since failure of the dam due to inadequate spillway capacity will not increase the potential for damage or loss of life from flooding to the inundation area.”
Mathiowetz recommended four qualifications to grant the variance, including
requiring prior approval for dam modification, if any, updating the city’s emergency plans annually and other lake flooding-related studies on a tighter schedule, and revoking the variance if the risks for potential flood damage increase.
Houston Engineering’s report, the variance request, and DANR’s staff recommendation and can be found
on DANR’s website.
“The city will continue moving forward with the Lake Mitchell improvement project,” Hanson said in a statement following the meeting.
