Colorado's Instream Flow Program (23-05)

The instream flow (ISF) program was created by legislation in 1973, which authorized the Colorado Water Conservation Board (CWCB) to appropriate or acquire water rights of natural streams and lakes to preserve the natural environment without diverting the water.  The ISF program recognized the need to balance the environmental benefits that come from maintaining water in a stream within the confines of the prior appropriation system.  Since 1973, CWCB has appropriated ISF water rights on close to 1,700 stream segments across more than 9,700 miles of stream, and natural lake level water rights on 480 natural lakes.