From The Pueblo Chieftain (Chris Woodka):

The state is looking at changes in water policy that will allow more efficient use of water without violating the prior appropriation doctrine of “first in time, first in use.” The policies deal with a “free river,” a concept that is not found in state statute, and futile calls, which are accounted for in law, but difficult to administer.

A free river occurs when every water right is satisfied, such as during a flood. In the Arkansas River basin, that condition has not occurred on a widespread scale since 1999, and occurred only about a dozen times in the last 60 years.

A futile call occurs when water in a reach of stream cannot physically be delivered to a senior water right in another area, even though it is in priority. That can occur during flash flooding, but also during well pumping when groundwater levels are high.

“The policies, especially the policy dealing with futile call, are less focused on the determination of the stream condition and instead are focused on administration of diversions once the stream condition has been determined,” Deputy State Engineer Kevin Rein said in an email last week.

“The actual objective of the two policies is to set out the direction through which the State Engineer’s Office and the division engineer can allow maximum utilization of the water supply while complying with the law and preventing injury.”

The policies most likely would be useful in discussions about flood control structures on Fountain Creek, particularly those designed to stop catastrophic floods. The question of water rights is under review by a technical committee.

It also could answer similar questions that have arisen in the South Platte River basin following record flooding in 2013.

The free river policy has provisions for storage under existing water rights or without a water right, as long as water is put to a beneficial use. The policy would allow for storage beyond a decreed water right. It would prevent injury to senior water rights and requires compliance with existing water storage regimen.

The water could be stored for a one-time use, with successive use of return flows determined by the division engineer on a case-by-case basis.

The futile call policy also makes provisions for diversion into storage with or without a water right, and outlines the state’s position that such diversions could become conditional or absolute water rights.

More Colorado Division of Water Resources coverage here.