Trying to keep a river from dying in Colorado

A brown trout caught during an electroshocking fish survey on the Big Cimarron River in Colorado. Trout Unlimited photo.

By Cary Denison

The Big Cimarron River shouldn’t go dry. This may seem like an obvious declaration about any trout stream. But the truth is, here in Colorado’s Gunnison Basin, and many other places in the West, water demands outpace supply even on average water years. This leaves many of the West’s rivers and streams, like the Big Cimarron in southwestern Colorado, depleted and fractured.

Big Cimarron River emanates from the bottom of Silver Jack Reservoir, a U.S. Bureau of Reclamation facility that captures water from the three major streams on the north-facing slope of the Cimarron Range. In normal years, summer flows hammer through tight canyons, around boulders the size or Clydesdales, passing stands of aspen and spruce as it plunges more than 1,700 feet in 20 miles on its way from Silver Jack down to the Bureau of Reclamation’s Crystal Reservoir. From there, it empties into the famed Black Canyon of the Gunnison River. Big Cimarron supports all manner of wildlife, including wild trout, and is a treasured spot for many western Colorado anglers.

But this summer was not normal—not by a long shot. And I shouldn’t have been shocked when I stood on a county road bridge and watched the remnants of the river collecting in dark pools behind powder grey boulders then disappearing into cracks in the river’s bed. The sight turned my stomach, especially because I knew that my work was supposed to prevent such an occurrence.

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The Big Cimarron River not looking so big during low water in 2018. Cary Denison/Trout Unlimited

I was in route to meet the superintendent of the Cimarron Canal and Bostwick Park Conservancy District, a conservancy district of nearly 5,000 acres which relies on the Big Cimarron watershed for irrigation water supply. The superintendent happens to be my older brother, who read my mood before I got out of my truck and nearly shouted, “I can’t seem to keep water in the creek, man… I release more every morning, but it just keeps dropping.” The juxtaposition of our roles in the watershed was on grand awkward display. His job is to deliver water to farmers and ranchers, and he has a senior water right for that purpose. My job is to look out for the health of a fishery which has next to no legal standing under western water law.

I acknowledged my brother’s statement with a nod and shrug, glanced at the canal carrying 83 cubic feet per-secondof water diverted from the river, and proceeded to haul tools from my truck to the river below the diversion where I would measure just 7 cfs of water. Both the U.S. Bureau of Reclamation and the Colorado Water Conservation Board have determined that 25 cfs is necessary to maintain a healthy river below the canal and downstream through the Cimarron State Wildlife Area, a rugged and picturesque chunk of public lands home to a healthy population of wild trout. The 7 cfs wasn’t near enough to provide adequate habitat or keep water temperatures low enough to support trout for the rest of the summer.

My brother and I had hatched a plan to increase flows in the river. The crux of the plan was to have the Colorado Division of Parks and Wildlife release water it owns in Silver Jack Reservoir to the river. Normally this water supports flat water recreation and stocked trout in the reservoir, draining this pool of water to save the creek was the tradeoff that seemed shrewd. With approval from the U.S. Bureau of Reclamation and assistance from Bostwick Park Conservancy District, CPW agreed to request the release of an additional 7 cfs of water to the Big Cimarron and which would be delivered to the confluence with the Gunnison.

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How the Big Cimarron River in Colorado should look in the summer months. Cary Denison/Trout Unlimited

Our efforts barely staved off disastrously low flow conditions in the most critical section of the Big Cimarron River. More importantly though, the arrangement laid the foundation for how we will react to drought in the future, and it complimented other projects Trout Unlimited and the Bostwick Park Conservancy District are pursuing. These efforts include increasing efficiency of the canal infrastructure, investigating the use of market-based water conservation tools, and working toward a watershed-wide planning effort that will help guide wise water use in the future. Just this week, the U.S. Bureau of Reclamation awarded the district a grant to replace a rusty old diversion gate at the Cimarron Canal diversion with a new gate that will be more reactive to downstream demands.

Watch a video explaining the importance of the Big Cimarron River in Colorado to agicultural and recreational users.

As I drove down the valley that that day, I chewed on author Norman Maclean’s statement about rivers at low summer flows: “… part of the way to know a thing is through its death.” Based on what I had seen on the Big Cimarron I decided there are some things I’d rather not know. With some luck, and more deals like the one we made in 2018, the Big Cimarron River will keep some of its secrets from future generations.

Cary Denison works for Trout Unlimited as the Gunnison Basin Project Manager under the Western Water and Habitat Program. He is based out of Montrose, Colo.