Radioactive Water May Have Seeped Into Mississippi River: Xcel Energy

MONTICELLO, MN — Radioactive groundwater leaked from Xcel Energy’s Monticello nuclear power plant may have seeped into the Mississippi River, the utility company announced Thursday.

Xcel determined that groundwater containing "very low" levels of tritium was near the Mississippi River, but no tritium has been detected in the river water itself "despite increased water sampling."

The closest sample to detect tritium was about 30 feet from the river, officials said. It detected about 1,000 picocuries per liter, below Safe Drinking Water Act standards of 20,000 picocuries per liter, according to Xcel.

Any presence of tritium in the river would be indistinguishable from what occurs naturally in the environment, the company said.

"Since the day we first confirmed a leak of tritiated water was present at the plant, we have worked around the clock to isolate and recover the affected groundwater," said Chris Clark, president of Xcel Energy Minnesota, in a statement.

"We take our responsibility for providing safe, reliable and clean energy to the community seriously, and will continue to work closely with state and federal regulators to ensure a thorough cleanup."

On Nov. 22, 2022, Xcel identified that 400,000 gallons of water containing tritium had leaked from a pipe inside the power plant.

Xcel did not disclose the leak to the public until March 16. Later that month, Xcel decided to temporarily shut down the power plant after more tritium leakage was discovered in the groundwater.

Xcel said it permanently fixed the in March and has since pumped more than 2.7 million gallons of groundwater for storage and reuse and has recovered over 75 percent of the tritium that was leaked.

"Most of the remaining tritium remains on-site closer to the plant structures," Xcel said.

"Activities at the site are being implemented to return all monitoring locations at the plant to Safe Drinking Water Act standards, or below 20,000 picocuries per liter. If at any point Xcel Energy detects tritium above Safe Drinking Water Act standards in river water, the company will notify regulators and the public."