The National Park Service has a plan for controlling the elk population in the Rocky Mountain National Park.
The animals are blamed for nearly eliminating aspen trees, willows and other plants native to Colorado.
Park service employees and authorized agents would be permitted to kill up to 200 elk every year in order get the number of growing herds down.
Two conservation groups are upset about this plan, saying they will sue the park service to block it. Forest guardians from Boulder and New Mexico want to restore wolves to the area in order to manage the herds.
Park officials say the earliest that elk would be shot would be January 2009.