On Monday afternoon (March 27), Xcel Energy notified the state duty officer that a change in water temperature led to a fish kill near its Monticello nuclear power plant. As part of its normal operations, warm water from the Monticello plant enters the river, which the fish get used to. The fish kill is unfortunate but not unexpected given the significant temperature change that can occur when warm water from the plant stops flowing to the river during a shut down in operations. At the time of the report, 230 fish had died including bass, channel catfish, common carp, and one or more species of sucker fish. The fish kill was not caused by tritium.
On Friday, March 24, Xcel Energy began a temporary shutdown of the Monticello plant to address a second leak of water containing tritium into groundwater at the facility. The Minnesota Department of Health and Minnesota Pollution Control Agency are monitoring samples taken from groundwater wells and have no evidence that the tritium has reached the Mississippi River or contaminated drinking water sources. The MPCA, MDH, and DNR continue to work together on this response.