Colorado water rights are based on the prior appropriation doctrine which states that the first in time is the first in right. This first come first served system has benefitted many people, but for most of its history has not been beneficial to the environment. In 1973, Colorado created their instream flow program. This program was designed to benefit the natural stream flow and lake levels in Colorado. The program has evolved since its creation to provide the greatest benefit possible to the natural environment. Instream flow water rights can only be held by the Colorado Water Conservation Board, but the water rights may be bought, donated or acquired. Due to the changing climate, Colorado is facing reductions in stream flow and lake levels. This paper hopes to explore what the impacts of flow reduction will be on the instream flow program and how the program may evolve to continue supporting Colorado’s natural environment.