ST. PETER — Minnesota state officials are concerned about the minimal requirements for private well owners to monitor the safety of their drinking water.

Chris Elvrum with the state health department said arsenic contamination is an emerging concern.

He said about 10 percent of wells in the state have unsafe amounts of arsenic, which occurs naturally in rocks and soil and can dissolve into groundwater. Elvrum said that the long-term risk is cancer.

About a fifth of the state’s drinking water is from private wells. Elvrum said many of the older wells have never been checked and newer wells often aren’t monitored after an initial sample is drawn.