DETROIT LAKES -- A watershed district in Detroit Lakes has been successful at preventing a non-native species from taking over four Becker County lakes.

The Pelican River Watershed District began tackling the invasion of flowering rush six years ago by doing basic scientific research on how the plant grows and thrives. The district spent about $25,000 a year on research.

John Madsen, who worked for the district at the time, found that applying herbicide underwater was most effective.

Assistant administrator Brent Alcott says researchers have found success when they dig up the plant rhizomes after multiple herbicide treatments. It takes about three years to see a significant reduction in flowering rush, and it requires annual herbicide applications to control the invasive plant.

Herbicide treatments cost about $50,000 a year.