The viability of our dams has been brought into question after massive rainfall, and the partial failure of a dam in northern Minnesota which has left many downstream praying for their livelihoods.
TMJ4's special reporting unit, Lighthouse, is taking a closer look at dams in our area. The overall picture is good — many dams are considered to be structurally sound or pose little threat if they were to fail, but officials are looking closely at one dam in Cedarburg.
In Wisconsin 59 dams are rated poor or unsatisfactory including the Woolen Mill dam in Cedarburg, which was built in 1939.
85 years later it's still standing but listed in "poor" condition on the National Inventory of Dams. The city of Cedarburg, which owns the dam, says $800,000 worth of repair work is expected to begin next year.
The Woolen Mill dam is currently labeled as a "significant" hazard, meaning, if it were to fail it could have a substantial impact on the environment, infrastructure, or property.
And while Cedarburg's city engineer says he has no concerns about the dam failing the Wisconsin DNR is shifting it to "high" hazard status, after a recent dam failure analysis. High hazard means that there could be loss of life downstream if the dam were to fail.
But how often does that happen? In the last 20 years, 34 dams have failed in Wisconsin. That's according to the Association of State Dam Safety Officials, only three of those were considered high hazard.
And, of the 59 mentioned earlier that are considered poor or unsatisfactory in Wisconsin, only 5 are high hazard, The vast majority, 201, are considered satisfactory or fair.
In our area, 5 high hazard dams are in Waukesha County. The U.S. Army Corps of Engineers lists the Pewaukee Lake dam as "satisfactory" — the safest rating. The Little Muskego Dam is also rated satisfactory. The Blott dam, Salow Lake dam, and Merton Rolling Mill dam all received fair ratings.
The National Inventory of Dams has data for more than 1,000 dams in Wisconsin. CLICK HERE if you want to find information about a dam in your community.
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