Things are wooly but not so wild in Lakewood, Colo. In April, the city employed 400 sheep to graze on knapweed, a sturdy, noxious weed that was choking native grasses atop Green Mountain.

In the past, Lakewood has used chemicals to control knapweed growth in small areas, such as at trailheads. However, the Green Mountain infestation covered 500 acres in a 1,600-acre open space park, and residents were concerned about using chemicals over such a large area.

Officials with the city's Regional Parks and Golf Department, which oversees maintenance of open spaces, considered dispatching crews to pull or burn the weeds. But sheep, they decided, would be the most economical and environmentally friendly solution to their problem.

The city contracted with a local herdsman to supply ewes and lambs, which grazed for a month, covering approximately 20 acres each day. In addition to paying $7,000 for sheep and sheep dog services, the city provided the contractor with 1,000 gallons of water per day for his herd, and it reimbursed him for animals lost to predators during the project. (Four sheep were killed — two by coyotes and two by rattlesnakes.)

In preparation for the project, the city launched a media campaign and met with homeowner associations to inform residents of the sheep and to encourage them to stay away from the animals. “If you are walking toward the sheep and either the sheep dogs or the sheep begin to watch you, you're too close,” one advisory warned. The city asked park visitors to keep their dogs leashed and to keep horses at a safe distance.

According to Kathy Cable, Lakewood's public information officer, the Green Mountain project was successful. The sheep cleared the prescribed area of knapweed, and there were “very few incidents” in which people or their pets disturbed them.

As expected, the knapweed began to grow within a month of being cleared by the sheep. The Department of Agriculture at Fort Collins-based Colorado State University is studying the overall impact of the project, and Lakewood will wait for the study results before deciding whether to repeat the grazing next year.