Colorado dam is accidentally being built on, and out of, uranium rocks

In case you don’t know, uranium is what’s used in nuclear reactors… Now that we understand that, I think we can all agree that’s not something we want in our water.

So needless to say this is not the kind of thing you want to find when you’re almost done with the tallest dam in the U.S. in the last two decades. Workers finishing the 350-foot Chimney Hollow Dam in Northern Colorado discovered uranium in the rockfill wall, traced to stone quarried on site.

Northern Water first saw hints at the end of last year and says the metal could leach into the new reservoir, which will serve more than a million people.

Engineers are talking with the EPA about options such as treating the first fill or letting the hundreds of billions of gallons planned for the lake dilute the risk.

Construction is still slated to wrap in about six weeks, with water pumping to start in August. Officials stress health limits haven’t been exceeded and say testing will continue long after taps open, calling the find a hurdle, not a deal-breaker.