WISCONSIN — Wisconsin ranks second in the nation for the amount of recent documented dam failures, according to a new study by Wisconsin Policy Forum.
The state had 34 recorded dam failures, where there was an unintended release of water between 2000 and 2023. The only other state to surpass that number is South Carolina.
Twenty-eight of those failures happened in the last six years and more than half occurred since 2020. None had catastrophic consequences, yet it raised questions about the future of the infrastructure, especially as extreme weather events with more rainfall increase.
Wisconsin has 4,000 dams across its 72 counties, ranging from large hydroelectric concrete ones to small earthen dams for farm ponds. Forty percent are owned by local governments, 29% are privately owned, 13% are state-owned, 9% are owned by a public utility, 7% are federally owned and the rest have mixed ownership.
A little over 1,000 are included in a national inventory, with about half listed with a primary purpose of recreation. Other purposes include hydroelectric power generation, flood risk reduction, fire protection, fishing and irrigation. Wisconsin ranks 30th for its number of dams.
Of those over 1,000 dams, around 200 are classified as “high hazard,” meaning failure or mis-operation of the dam could cause the loss of human life. Nearly half are owned by local governments.
Wisconsin is ranked 27th nationally for its number of high hazard dams.
In the state’s 34 failures, only three were high hazard potential dams. One was a significant hazard dam, meaning failure or mis-operation could result in “economic loss, environmental damage, disruption of lifeline facilities or impact other concerns.” Eighteen were low-hazard dams, meaning there wouldn’t be any loss of life or economic/environmental losses. The rest were not classified.
High hazard dams are actually increasing nationwide. Officials say that’s due to development moving closer to dams that were once rural. In Wisconsin, the number of high-hazard dams increased by 29 from 1994 to 2024.
Despite the increase, officials said Wisconsin fairs better than “most other states” for its high-hazard dam conditions. Although Policy Forum officials said it can be hard to compare states’ data due to missing data points, Wisconsin ranks eighth lowest in the country for high hazard dams in poor condition.
Recent data shows only five, or 2.4%, of those dams were in poor or unsatisfactory condition. Conditions have even improved, as in 2019, 10.1% were considered poor or unsatisfactory. The data available on these ratings has grown to provide a fuller picture in the last decade. Between 2009 and 2013, only 25% of the high-hazard dams in the state had condition ratings, but by 2015, 95% had them.
Policy Forum officials said this shows the effort by state officials and dam owners to make sure data is up to date.
Funding to maintain the dams comes from the state budget, which provides grants to local governments. Gov. Tony Evers, in his 2023-25 budget, included $10 million for this, the same amount he allocated in 2021. However, that number was pared back to $4 million in the recent budget by the Legislature, consistent with every two-year state budget prior to 2021.
Wisconsin Policy Forum said the funding has been “sufficient” up to this point to improve conditions of dams but pointed to the increase in failures and a changing climate as posing “new and greater tests” to the infrastructure.
That has some removing them altogether.
At least 25 dams have been removed from the state since 2000. While some dams are still playing vital roles in providing electricity, others are no longer useful and instead pose potentially more trouble than they are worth, according to the report. Wisconsin Policy Forum pointed to Vernon County as an example. The county has plans to remove or get rid of up to 23 dams due to a massive rainstorm in 2018, which caused five dam failures.
Despite some disagreement among the public, Policy Forum officials said that removals can have positive benefits for wildlife and fish.
While none of the 34 failures had loss of life or property damage exceeding $100,000, there were still effects felt by those in the community.
A recent dam failure in Manawa resulted in the evacuation of around 100 nearby residents. Officials also projected it caused close to $6 million in property damage. Policy Forum officials said the failure of this dam “may be the state’s costliest since 2000.”
And that was for a lower hazard dam. Policy Forum officials cautioned “the stakes would be even higher” if other high-risk dams in the state were to fail.
“In the years to come, state and local leaders face difficult choices about where to invest in maintaining and improving dams to weather future floods and where to consider removing them altogether from the landscape,” officials said in the report.