Arapaho National Wildlife Refuge manages cattle grazing permittees in riparian meadow and irrigated meadow units. The refuge Comprehensive Conservation Plan (CCP) has specific management objectives for these vegetation communities (U.S. Fish and Wildlife Service, 2004). Grazing is used as a management tool to achieve CCP objectives for vegetation composition and structure and thereby maintain and enhance nesting habitat for waterfowl, brood-rearing habitat for greater sage-grouse, and habitat for other native wildlife. The grazing season spans July 1 to September 30. Most meadow units are on a 3- or 4-year grazing rotation (grazed one year out of every three or four years) except the Midland and Tour Route meadow units, where all pastures are grazed on any year but for only part of the grazing season for short time. Annual rainfall causes forage biomass to fluctuate, thus in drought years there is sometimes a need for a pasture that was scheduled to be rested to instead be grazed. Water availability determines the extent to which irrigation can be used. In a year with high precipitation , there is adequate water for irrigation. In a year with low precipitation, it is difficult to irrigate the Midland and North River Units because they have limited water rights compared to other water users.