Xcel Energy is still working to contain the tritium that leaked from the Nuclear Power facility in Monticello. The leak, which occurred two years ago, is still affecting areas around the plant. Earlier this week, the power company noted that tritium was detected in monitoring wells closer to the Mississippi River. Here's what Xcel had to say in a release sent to residents in the Monticello area, as shared by the City of Monticello on social media.

Here's what we know

The City of Monticello shared the tritium news via social media on Thursday morning.

What happened?

Back in 2022 a leak was noticed after some 400,000 gallons of 'dirty' water was found to be leaking from the plant, that water had tritium in it. ANS.org wrote in March 2023 that  a "leak of some 400,000 gallons of tritium-containing water at Minnesota’s Monticello nuclear power plant in 2022 has sparked a flood of news stories over the past few days—in large part because the general public had previously been unaware of the leak."

Now it appears that the leak is still causing issues close to the Mississippi River.

The City of Monitcello linked to an official press release from Xcel Energy, stating that the tritium that was located closer to the Mississippi River in two monitoring wells is 'low' and safe, as it falls below the levels set by the EPA.

Earlier this week, groundwater monitoring wells identified low levels of tritium in two additional monitoring wells near the Mississippi River, both at levels below the EPA standard. We are adjusting the amount of water we pump to help control the flow of groundwater and recover it more effectively. At no point has tritium been detected in the river itself above naturally occurring levels. - Xcel Energy

The Minnesota-based power producer will be pumping more water from those wells to keep the amount of tritium from increasing, according to the online press release. 

What is Tritium?

According to the Canadian Nuclear Safety Commission: 

"Tritium is a radioactive isotope of hydrogen. It has the same number of protons and electrons as hydrogen but has 2 neutrons, whereas regular hydrogen does not have any. This makes tritium unstable and radioactive. Tritium is produced naturally from interactions of cosmic rays with gases in the upper atmosphere, and is also a by-product of nuclear reactors.

Like all radioactive isotopes, tritium decays. As it decays, it emits beta radiation.

The physical half-life of tritium is 12.33 years, meaning that it takes just over 12 years for tritium to decay to half of its original amount. As tritium decays, it changes to helium."

There is alot of activity at the power plant, why?

Residents of Monitcello will see an increase in activity around the plant starting today, Friday, April 18th, as the plant will be undergoing a normal and scheduled "refueling outage".

Residents in the area can expect to see increased activity at the plant around the clock, as well as at local restaurants and hotels as several hundred specialized contractors arrive to help complete the work safely and effectively over the next month. - Xcel Energy

According to an MPR article from 2025, the plant in Monitcello "produces enough energy to power more than half a million homes in the Upper Midwest," and is also one of Monticello's largest employers.