The North Fork Republican River drains an area of 5,086 square miles (13,170 km2), including 4,449 square miles (11,520 km2), or 87.5%, in eastern Colorado, 575 square miles (1,490 km2), or 11.3%, in southwestern Nebraska, and 62 square miles (160 km2), or 1.2%, in northwestern Kansas.[3]
Use of water from the North Fork Republican River is governed by the Republican River Compact, a water agreement among the U.S. states of Colorado, Nebraska, and Kansas signed on 1942-12-31.