Some rejiggering of reservoir operations in the upper Colorado River watershed is taking the heat off trout in Grand County through the early release of water that had been set aside for endangered fish in Mesa County.

The approach is being made possible by storing water elsewhere so it can be released for the endangered fish when they need it later.

Under the agreement involving the U.S. Fish and Wildlife Service, the U.S. Bureau of Reclamation and Colorado River District, an additional 35 cubic feet per second of water started being released last week from Lake Granby, also known as Granby Reservoir, in the Colorado River headwaters. That nearly doubled Colorado River flows immediately downstream.

The increased flows help reduce daytime temperatures in the river, which had begun topping 60 degrees and threatening the health of trout. The releases involve water normally stored in Granby for use in boosting flows in the river near Grand Junction for endangered fish such as the humpback chub and razorback sucker.

The endangered fish still will get water under the deal, however. In exchange for the additional water coming out of Granby, the river district is withholding 35 cfs of water from Wolford Mountain Reservoir, which sits above Kremmling on Muddy Creek, a Colorado River tributary. That's below the problem stretch of the Colorado River, thanks to inflows to the river coming from Muddy Creek and other tributaries, so the Wolford water that's being withheld doesn't hold the importance to the trout that the released Granby water does.

"There's plenty of water in the river except for in that stretch below Granby," said Jim Pokrandt, a river district spokesman.

Pokrandt said the Colorado River is currently a "free river" right now in Colorado. There are no calls on it to meet the needs of senior water rights holders when flows are more limited. But the upper stretch in Grand County in the Hot Sulphur Springs area is depleted due to transmountain diversions to the Front Range.

Withholding the Wolford water means it will be available for the endangered fish during lower-flow periods on the Colorado River in Mesa County, in lieu of the water that is being released from Granby.

Game fishing is a big part of Grand County's economy.

The trout-water releases were continuing as of Wednesday. Pokrandt said there's no hard date set for ending them. The end date could depend on factors including the possibility of a heavy monsoonal rain period arriving along with cooler temperature, making the releases no longer needed.

Altogether, more than 5,000 acre-feet of water is stored in Granby each year to help endangered fish. So far 382 acre-feet have been released for the sake of the trout and offset by an equal amount of water being stored in Wolford. An acre-foot is about 326,000 gallons.

In a news release, the river district noted that in recent years it has been a catalyst and source of stored water releases to meet a number of needs. During last year's drought, it used water stored in Ruedi Reservoir to boost flows in the Roaring Fork River and ultimately benefit endangered fish, power production and agriculture in the Grand Valley. It also encouraged other entities owning water in Ruedi to do the same.

Over the winter Ruedi water owned by the river district was released into the Fryingpan River immediately downstream to prevent river icing.

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