COTTAGE GROVE — A herd of 20 goats is been grazing on invasive plants at Cottage Grove Ravine Regional Park for a week or two, kicking off Washington County’s efforts to use a nonchemical approach to a buckthorn infestation.

Jake Langeslag, who owns Faribault-based goat Dispatch, and herd manager Jarett Spitzack released the goats on the north end of the park today, according to a press release.

Langeslag, who started his company over four years ago, said he was initially surprised how well they ate the plants. He has increased his goat count from six to 120, tackling up to 50 projects a year.

The goats work as a group to lower branches and eat the plant’s leaves, reducing the strength of the plant and later killing it. When the goats are full, they congregate in the sun to digest and rehydrate before continuing their work. Goats eat 3 percent to 5 percent of their body weight daily.

“The nice thing about goats is that we don’t have to worry about rain, weather conditions, wind and all that type of stuff,” said the county’s natural resource coordinator Dan MacSwain.

The practice isn’t new to the region.

Goats were used to eat buckthorn at Pine Bend Refinery in Rosemount in 2013. The next year, they chomped on goldenrod at Pilot Knob hill, a historic site in Mendota Heights.

According to the Minnesota Department of Natural Resources, buckthorn is a shrub that can reach 25 feet, and sprouts its leaves earlier than native plants in the spring, making it difficult for native plants to receive enough light and water.

If county parks officials see that the goats improve the buckthorn infestation, they may consider using the service long-term. MacSwain said the county will also continue using hand tools and some chemicals to fight the infestation.