Jo Evans

An instream flow (ISF) right is a state water right to ensure specific amount of water flows between 2 specified points. It is measured in cubic feet per second (cfs) It has a priority date and is established by the state on behalf of the public. It is to protect the environment to a reasonable degree, and thanks to CTU and SB156 a few years ago, also to improve the stream environment.

Instream flow rights are held by the state itself. As a real and valid state water right, ISF is subject to all the procedures, protections and stipulations of any other Colorado water right. The state may acquire existing decreed rights through purchase or donation and petition the court to change the use to an instream flow right. It may also appropriate unappropriated water in the same manner as anyone else.

Only the state may hold an instream flow right. You and I can not. The state acquires the right on behalf of the people of Colorado. If a subsequent proposed use by another could harm (materially injure) a degreed ISF, the state may object. If the state does not object, a member of the public may intervene to protect the public’s right.

ISF is the only beneficial use of water that does not require a diversion.

(See also:

Water Law 101, Comparison chart on instream uses, and Colorado’s Instream Flow Program)