The U.S. Army Corps of Engineers has changed its rating of the Oahe Dam north of Pierre from “high risk” to “very high risk“. But be chill—Bob Mercer reports this rating doesn’t mean we have to evacuate the capital:
The corps operates Oahe Dam and five other major dams on the Missouri River as part of its Omaha district. U.S. Army Colonel Joe Sahl is the district commander. Sahl told reporters during a briefing on Wednesday afternoon that state, tribal and local officials were previously made aware of the results of the April assessment and the related decision to change the rating.
Sahl emphasized there is no immediate danger to the public and the corps plans no changes to the hydropower dam’s operation [Bob Mercer, “Corps Shifts Oahe Dam to Highest Risk Category,” KELO-TV, 2026.10.01].
It appears the riskier rating just moves Oahe to the top of the list for upgrades:
Oahe Reservoir, which stretches upstream 231 miles through South Dakota and reaches into North Dakota, is the fourth-largest among the 700-some reservoirs managed by the corps, according to Sahl. Regarding the change in classification to very high risk, Sahl said, “This classification moves Oahe to the front of the line for investment.”
Asked to clarify whether that means Oahe would be placed ahead of all dams the corps manages, Sahl said, “There is no higher classification than where we’ve classified Oahe.” He added, “It is one of their top priorities for investment.”
The next step at Oahe will be what the corps calls “a multi-year dam safety modification study” intended to “identify and evaluate long-term measures for strengthening the dam’s performance during rare, extreme flood events.” The study will build on risk-reduction work that has either been completed or is under way [Mercer, 2026.10.01].
But be careful, South Dakota: if you elect Democrats this November, Donald Trump might cut funding for the Oahe Dam and anything else the Army Corps of Engineers does in South Dakota.
The death of the Missouri River ecosystem in South Dakota began with the European invasion, was accelerated by the Homestake Mining Company and sealed with the construction of the mainstem dams. Today, the US Army Corps of Engineers has cancelled Spring Pulses on the Missouri River not because of low flows but because the sediment is so poisonous it would kill the very species it says it’s trying to preserve. Endangered pallid sturgeon, paddlefish, catfish and most other organisms cope with lethal levels of mercury throughout the South Dakota portion of the Missouri River.
South Dakota receives zero dollars for hydropower generation but eminent domain forces transmission lines to be built so how is that in the state’s best interest? Silt deposits are the responsibility of the state so AG Jackley should sue the mining and ag industries for that runoff instead of blaming the Corps.