The South Dakota Department of Agriculture and Natural Resources is recommending approval of a variance request tied to the Lake Mitchell Dam, a move that could help restart long-planned improvement efforts for the lake and surrounding watershed.
Below is the full press release from “Friends of the Firesteel”
RE: Lake Mitchell Dam & Downstream Analysis Update
Dear Community of Lake Mitchell and Firesteel Creek,
We want to update you with the latest information. The South Dakota Department of Agriculture and Natural Resources (DANR) reviewed the Lake Mitchell dam and downstream analysis and is recommending approval of the variance request.
Houston Engineering finalized their study on the downstream effects of catastrophic events on Lake Mitchell as was required by the South Dakota DANR for the City of Mitchell. Multiple catastrophic events were studied by Houston Engineering which included a spillway collapse on a sunny day, and a 50% Probable Maximum Flood (PMF), which means 50% of a 1000-year rain-event equivalent to around 17 inches of rain falling over a 48-hour period, equally distributed across 350,0000 acres of the Firesteel Creek watershed. A Probable Maximum Flood event has an annual likely occurrence of . 1%. DANR requires that the inflow of a 50% Probable Maximum Flood event, does not overtop the lake earth-embankment, or essentially where the new bike trail is located. According to the computer modeling results, the earthen dam was only able to hold back the inflow of a 23% Probable Maximum Flood event.
During the modeling, it was determined that 18 assets are at risk downstream of the lake during the 1,000- year rain-event. The study concluded that the risk to the public is not significantly increased between the different scenarios of the 23% PMF versus the 50% PMF and that a request for a variance to the SD DANR requirement is justified.
(A 501(c)(3) Non-Profit) Est. 2018
Goal: To restore and maintain Lake Mitchell and the Firesteel watershed area
Great news. The DANR has reviewed the analysis and report by Houston Engineering and is recommending approval of the variance request. In addition to the analysis, the City of Mitchell will have an emergency preparedness plan (EPP) completed this summer. The EPP will be reviewed and updated annually by Houston Engineering. As part of the city’s EPP, an early contact system will be implemented to ensure the downstream affected residences are notified if such a rain event happens so evacuation can occur. Review of this variance recommendation will take place at the May 2026 SD DANR Meeting. Friends of the Firesteel is optimistic that the recommendation of a variance will get Lake Mitchell and Firesteel Creek Watershed improvement work back on track.
Thank you for your continued support to save Lake Mitchel
More info on the project can be found on the “Save Lake Mitchell” Facebook page.
