#Snowpack/#Runoff/#Drought news

From Wyoming Public Media (Judy Fahys):

Drought has basically divided the Mountain West into two separate regions this year.

Storms kept Idaho, Montana and Wyoming wet over the winter, and the national Drought Monitor shows no drought in those states.

But high pressure dogged Utah and most of Colorado this winter. Now the ground is dry and the snowpack is lean, even though March was stormy…

Brian McInerney, a hydrologist for the National Weather Service in Salt Lake City, said a wet winter last year helped top off the reservoirs that store water for drinking and irrigation.

“I think we’re okay this year,” he said. “I think if we look at the 2018 water year, what we’ll find is low snowpack but adequate reservoir storage.”

The National Climate Prediction Center is forecasting that the drought will persist this spring in both Utah and Colorado.

From AccuWeather (Ashley Williams):

Snowmelt from the Colorado River Basin contributes about 70 percent of total water supplies for more than half of Southern California and most of southern Nevada, according to the California-Nevada Climate Applications Program. Its low salt content makes snowmelt a useful fresh water source of drinking supplies.

With increasingly warmer winters and a diminishing snowpack in recent years, the lack of snowmelt might pose problems for the communities that need it.

Measurements of the Sierra Nevada snowpack in early spring 2018 revealed that the snowpack remained below normal.

“We’ve seen the typical elevation at which rain transitions into snow, on average, go up over the past decade,” said Nina Oakley, a regional climatologist at the Desert Research Institute’s Western Regional Climate Center in Reno, Nevada.

“Now, we’re seeing less snowpack building, and it’s been observed in the West that with warmer spring temperatures, we’re seeing earlier spring snowmelt runoff,” Oakley said.

A 2017 report from the National Center for Atmospheric Research showed that warmer winters are causing mountain snowpack to melt both earlier and slower. This is due to less thawing occurring during the lengthier nights and weak sunlight of early spring, according to Colorado Public Radio News.

University of Nevada researchers have reported that the cause of less efficient snowmelt runoff is that “slower snowmelt reduces the amount of moisture being pushed deep into the subsurface, where it is less likely to evaporate.”

Researchers believe one effect of slower snowmelt on water supply and hydropower production could be that the snowmelt will move less efficiently downstream to reservoirs at times when it’s especially needed, such as during drier periods.

From the Associated Press via US News & World Report:

The median amount of water contained within New Mexico’s snowpack statewide for the start of April is the lowest on record since at least 2000.

Officials with the National Weather Service in Albuquerque say the measurement — known as the snow-water equivalent — at the Hopewell site in Rio Arriba County had the lowest value since records began in 1980.

They also say the snowpack in southern Colorado is at about 50 percent now and just trace amounts remain in New Mexico’s basins.

The grim statistics come as more than one-third of the state contends with extreme drought.

From Steamboat Today (Matt Stensland):

A couple standout powder days were not enough to help the Steamboat Ski Area reach its average March snowfall.

The ski area received 36.25 inches of snow in March compared to the 20-year average of 48.39 inches.

As of Sunday, the snow total for this season stood at 229 inches. On average, the ski area receives 327 inches of snow each season.

The ski area during the month of April gets an average of 14.66 inches of snow, and two inches of new snow was reported at 1 p.m. Sunday for the first day of April.

From The Summit Daily (Deepan Dutta):

In Summit, snowpack is at a relatively healthy 88 percent of average. However, Wineland noted that in southern Colorado, some places are seeing 60 to even 30 percent of average snowpack. That will mean more water usage downriver this summer, which affects water rights and availability in the northern and central parts of the state.

Wineland then presented this winter’s butcher’s bill by referring to a precipitation and temperature chart for Summit over the past few months.

“November, higher than average temperatures, lower than average precipitation,” Wineland said. “December, higher than average temperatures, lower than average precipitation. January, the same.”

February, on the other hand, saw cooler temperatures and higher precipitation, which offered some, but far from enough moisture to raise the “fuel-moisture index,” a tool that determines how much moisture is present in fuel sources — such as grass, brush and trees — to mitigate the chances of wildfire. The higher the fuel moisture, the less chance for wildfire. On the converse, lower- or no-fuel moisture may lead to larger, hotter forest fires burning out of control.

Wineland then dropped the sobering bombshell that offered the best insight into the danger presented by this upcoming wildfire season.

“2002 and 2012 were Colorado’s driest winters on record,” Wineland said, “and this will be Colorado’s third driest winter on record.”

Wineland complicated the picture by noting how Colorado was in a weather band between the warmer El Nino phenomena in the eastern Pacific ocean and the cooler La Nina; a period colloquially known as “La Nada.” During this unpredictable “neutral” period, it is extremely tough to properly forecast regional temperature and precipitation, and thus tougher to know how bad the wildfires will be this summer.

From Aspen Journalism (Brent Gardner-Smith) via The Aspen Times:

Federal officials told regional water managers last week not to plan on coordinated reservoir releases this spring to help endangered fish in the Colorado River near Grand Junction as there’s likely not going to be enough water.

“It’s difficult for me to find the water in my forecast,” said Victor Lee, a hydraulic engineer with the Bureau of Reclamation during a conference call March 27 with regional water managers.

For the past three years, 29,400 to 35,700 acre-feet of “surplus” water has been released out of various combinations of Ruedi, Wolford, Williams Fork, Green Mountain, Homestake, Willow Creek and Granby reservoirs to bolster spring flows.

The water is released in early June to help maintain critical habitat in a 15-mile stretch of the Colorado River between Palisade and Grand Junction, above the river’s confluence with the Gunnison River.

Big peak flows clean the cobble on the river bottom where endangered fish lay their eggs. And the high flows frustrate non-native fish species that prey on young native fish, a major obstacle to growing the endangered fish populations.

The coordinated release of reservoir water is meant to offset the immediate impact of two large water diversion structures with senior water rights at the top of the 15-mile reach that send irrigation water to the Grand Valley.

It also offsets the extensive series of transmountain diversions that occur at the top of the system for Front Range use, and the irrigation diversions from the river system on the Western Slope.

Keeping the endangered fish populations stable matters to regional water managers because it allows current and future water uses to occur. If the fish populations continue to decline, the rules in the Endangered Species Act could produce a much different regulatory climate.

To avoid that, water managers work together through the Upper Colorado River Endangered Fish Recovery Program, which is managed by personnel at the U.S. Fish and Wildlife Service.

The coordinated releases of water from upstream reservoirs in the spring are part of the effort.

Last year the effort increased the peak flow in the 15-mile reach from more than 12,000 cubic feet per second to over 14,000 cfs on about June 10.

The coordinated releases from the reservoirs have happened in 10 out of 20 years since 1997. In wet years such as 2011, spring flows are judged to be high enough.

And in low years, as this one is expected to be, it can be hard for water managers to find water to spare for the endangered fish.

“It just doesn’t look like we’re going to have the coordinated reservoir releases from the reservoir this year, it being such a dry year,” said Tim Miller, a Reclamation hydrologist who manages water in Ruedi Reservoir on the Fryingpan River above Basalt. “And we need to make sure we fill, that’s the No. 1 priority.”

Last year, as part of the spring release program, Ruedi Reservoir sent 4,501 acre-feet into the lower Fryingpan River toward the 15-mile reach, causing flows to rise June 2 from 200 cfs to 600 cfs on June 7, before stepping back down to 200 cfs by June 14.

Miller’s March 1 forecast this year showed a water-supply forecast, which is based on snowpack, of 69 percent in the upper Fryingpan River basin above the reservoir.

And like other regional water managers, he doesn’t expect this week’s forecast to look any better.

Miller still expects to fill up the 100,000 acre-foot Ruedi Reservoir by early July as usual, there’s not much “wiggle room” in the forecast, or the snowpack.

A slow-fill of Ruedi means the Fryingpan below the reservoir also will see a low and steady flow of water — probably not more than 150 cfs and perhaps less — from May 1 until late July or early August, when late summer releases begin, Miller said.

Other reservoir managers in the upper Colorado River basin are facing similar challenges, and Don Anderson, the instream flow coordinator for the endangered fish recovery program, understands they don’t have “fish water” to release every spring.

“It’s an operational call that they make based on their comfort level of either bypassing or releasing inflows with the confidence that they are not jeopardizing their storage conditions later in the season,” Anderson said.

CHUB LIFE

The coordinated high spring releases are meant to benefit four species of endangered fish that still eek out a living in the Colorado River between Rifle and Westwater Canyon.

The humpback chub and Colorado pikeminnow populations are still wild, while the bonytail and razorback sucker populations are stocked.

And the chub has recently been in the spotlight, as the U.S. Fish and Wildlife service announced March 22 that a five-year study has shown the chub could soon be downlisted from “endangered” to “threatened.”

At the core of that recommendation was the relatively stable population of about 12,000 adult humpback chub that live in the Little Colorado River in the Grand Canyon, where the muscular torpedo-shaped fish evolved 3 million to 5 million years ago.

There also are about 400 adult humpback chubs living in the Black Rocks section of the Colorado River, just west of Loma. And there are another 2,000 to 3,500 adults in Westwater Canyon just over the state line.

Both population groups appear relatively stable, but their future is uncertain. A similar population group in the Yampa River, last seen in 2004, is now considered “extirpated,” meaning eliminated.

The biggest challenges for the remaining humpback chubs are lack of adequate stream flow and the spread of non-native predatory fish.

“What we really have to worry about in these low-flow years are critters like smallmouth bass that have not shown up yet in Black Rocks and Westwater in any kind of numbers,” said Tom Chart, the director of the endangered fish recovery program. “These low-flow years do seem to benefit the non-native species preferentially over the native fish.”

LOW-FLOW TARGET

Regional water managers like Miller at Ruedi Reservoir also work together in late summer to release water to boost low flows in the 15-mile reach in the late summer.

Last year, 79,000 acre-feet of late-season fish water was released from participating reservoirs. The water kept the river closer to the targeted-flow of 1,240 cfs instead of the 500-cfs-levels it was dropping to in August.

Of that 79,000 acre-feet released from the reservoirs last year for late-season flows in the 15-mile reach, Ruedi contributed 21,413 acre-feet of water, sending it downstream between Aug. 7 and Oct. 16.

But it’s expected that there will be less late-season fish water this year, both out of Ruedi and in general.

On last week’s conference call, officials with the fish recovery program said they intend to set a low-flow target of just 810 cubic feet per second for late summer flows in the 15-mile reach, instead of last year’s target of 1,240 cfs.

The decision could change if spring snows come. But if the low-flow target is definitively set this year as expected, it will be the first time since 2012.

Anderson said that given the dry conditions and the challenges that reservoir operators are facing it is “smart and prudent to look at the lower target.”

“It’s just looking at what’s really going to be feasibly achievable given the actual wet water we have to work with,” Anderson said.

And even the low-flow target of 810 cfs could be hard to hit this year.

“We can’t always get there sometimes with the water that is available, but we can at least do the best we can to close that gap,” he said.

Westwide SNOTEL basin-filled map April 3, 2018 via the NRCS.

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