BROOTEN (AP) - As irrigation booms in Minnesota, a report says hundreds of farmers appear to be pumping groundwater for their crops without the required state permits.

Of the roughly 1,200 crop irrigation wells drilled from 2008 to 2012, more than 200 likely are operating without a permit. Nearly 200 others operated without a permit until the past year or so.

The lack of permits hampers the state's ability to manage its groundwater resources. MPR says tens of millions of gallons of water are likely being pumped without the state's knowledge, and some irrigators are boosting yields and profits while avoiding oversight and fees.

The Department of Natural Resources acknowledges that some users have been getting away without permits but says it has gotten more aggressive recently.