By Sandra Postel and Todd Reeve

The infamous use-it-or lose-it rule is arguably the biggest barrier to water conservation and river-flow restoration in the western United States.

It basically says that if anyone holding water rights does not put them to full use, the unused portion can be taken away and allocated to serve the needs of another water user. Historically, using a water right to keep a river flowing for fish or the health of the ecosystem was not considered a “beneficial use” of water, and therefore could result in losing that water right.

Perversely, the use-it-or-lose-it principle gives water rights holders an incentive to waste water so that they don’t risk losing any of their increasingly valuable water rights.

Bit by bit, however, new state laws and innovative projects are chipping away at this outdated rule, and keeping rivers flowing for fish, wildlife and local communities. A groundbreaking 2013 Colorado law provides new flexibility that allows water rights owners to allocate water to a river during times of critical low flow.

In the Colorado River headwaters, just outside of Rocky Mountain National Park, Willow Creek is providing a test case for the new law.

There, Witt Caruthers, a ranch owner with rights to divert a portion of Willow Creek’s water, decided to develop a plan allowing him to leave water in the creek for up to five years during a 10-year period—without the threat of the “use it or lose it” provision.

The water for Caruthers’ ranch, which is delivered through two irrigation ditches not far from where Willow Creek meets the Colorado River, fills stock tanks for cattle and irrigates 70 acres (28.3 hectares) of pasture. Typically, the diversions begin in May and continue through late summer. By that time, rivers and streams that rely on snow melt are running low – and after diverters take their share of water, many streams are at risk of running completely dry. Such was the case with Willow Creek.

For Caruthers the conservation project offered a chance to do something positive for Willow Creek and to set a precedent for other rivers in the drought-stricken West.

“Colorado’s water system created an incentive to use our water even in times when it’s not absolutely necessary,” Caruthers told the Denver Post. “When you’re under that pressure to use it or lose it, you’re almost forced to abuse it. That’s to the detriment of all.”

Caruthers and his partners worked with the Denver-based Colorado Water Trust (CWT) to design the project. It essentially involves curtailing diversions from Willow Creek when flows drop dangerously low. Because there are no other diverters immediately downstream, the enhanced flows will benefit not only the lower half mile of Willow Creek, but also some 4.3 miles of the upper Colorado –including populations of brook and brown trout.

Although the project restores only a small volume of water to the stream, that additional flow at crucial times of the year can help keep Willow Creek connected to the Colorado River, enhance water quality, and sustain fish and other aquatic organisms.

This past June, the chief engineer of the Colorado River District approved the CWT-Caruthers conservation program.

The Willow Creek project also sets a precedent that could be a game-changer for other Colorado rivers, as well as for farmers and ranchers that have the ability to use less water and share any surplus with a river. For those who desire to balance economic productivity with recreation interests, fish and wildlife needs, and community benefits, this new law offers a positive step forward.

The beauty of the new law, says Amy Beatie, CWT’s Executive Director, “is that it allows for a very simple, low-risk and flexible way for a water user to experiment with leaving water in a river.”

“It is one of the most straightforward programs the state has ever created to allow flexibility in water use,” Beatie continued, “and it has potential to benefit entire water user communities that are interested in collaborating to keep water in the river.

This 2013 Colorado law provides added flexibility and longer-term benefits for rivers than a 2003 state law that was designed to ensure that rivers aren’t denied water when they need it most.

The 2003 law was first tested during the drought of 2012 on the Yampa River, another upper Colorado tributary and the heartbeat of the popular tourist town of Steamboat Springs. That law allows farmers, ranchers and water districts to temporarily lease water to rivers and streams in times of need.

The following year, CWT and partners replicated that leasing approach on several other rivers, including the Fraser, another headwater tributary. The Fraser suffers not only from low flows during droughts, but also from trans-continental tunnel systems that divert its water to the Denver area.

Colorado’s 2013 law also gives water-rights protection to participants in the Colorado River System Conservation Program, an $11 million pilot initiative of the US Bureau of Reclamation and the water agencies supplying the four largest cities drawing upon the Colorado River – Denver, Los Angeles, Las Vegas and Phoenix. Some $2.75 million will be spent in the upper Colorado River Basin.

Although a small step for the restoration of the state’s rivers, Colorado’s new law breaks important new ground. And it may just inspire other western states to add flexibility to their systems of water rights so that more rivers can keep flowing.

Originally published at National Geogrpahic Newswatch.