Winter’s unlikely weather may be new norm for water forecasters

Neversink 2017

Neversink was a popular fishing resort on the Gunnison River below Gunnison before Blue Mesa Dam backed up the river to nine miles west of Gunnison. Photo and story by Dave Buchanan.

This past spring year was particularly mettlesome for water managers seeking to balance water supplies and demand in the Upper Gunnison River Basin.

Although there currently are no shortages of water this year, the vagaries of last winter, from unseasonably warm to unseasonably cold, may hold some warning about future water forecasting for regional hydrologists, cautioned Greg Smith, Senior Hydrologist for NOAA’s Colorado River Basin Forecasting Center in Salt Lake.

The art of forecasting water supplies has as one of its main tools historical data and the rapidity of changes in the Earth’s climate recently has been handcuffing the best efforts of forecasters, said Smith during the last week’s Aspinall Unit Operations meeting in Grand Junction.

The quarterly meetings, sponsored by the Western Colorado Area Office of the Bureau of Reclamation, offer a look at what hydrologists and weather forecasters portend for future water supplies in the Upper Colorado River Basin.

“2017 was challenging,” Smith said when addressing the year’s weather. “When we go from one (weather) extreme to the other, as we have seen this year, that makes our job even more difficult.”

summer snotel

The Beartown SNOTEL site in Mineral County gets some summer maintenance from Zach Wilson. This winter, similar remote-sensing sites were buried by snow. Photo by Mike Ardison.

A pair of linked examples was the unusual warming in March, which caused some very early low-elevation melting and ensuing runoff, followed by an unseasonably cold May (“February-like temperatures,” Smith said) which drastically slowed that runoff and caused concern among water managers wondering when and if the runoff would begin anew.

All this was tied to the near-record snows of late December and January, which overwhelmed some of the region’s remote-sensing SNOTEL sites.

“Several sites quit reporting and we thought they had broken but in reality they had been completely buried by the snow,” Smith said. “In March, a lot of the sites (in the Upper Gunnison Basin) recorded their highest totals on record … some of which go back 39 years.”

Are the aberrant weather patterns of last winter just that or are they indications of a new normal that eventually will become part of the historical data?

Smith isn’t sure.

“Well, we try to use long-term records in making our (water-supply) forecasts, at least 20 years or more,” Smith said. “So even these recent weather patterns will take a while to become part of the permanent record.

“And we’re certainly aware of weather changes. Even a few degrees one way or the other affects snowmelt and eventually water supplies.”

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Water managers face unusual dilemma: Too much water

Blue Mesa full 2017

A summer storm over Blue Mesa Reservoir west of Gunnison. At this writing, the reservoir was more than 98 percent full. Story and photo by Dave Buchanan.

“I’ve been rich and I’ve been poor. It’s better to be rich.” – Gertrude Stein, American novelist.

Farmers, ranchers and domestic water managers all agree with Ms. Stein when it comes to matters of water. Rich is much better than poor.

And water-rich is what the Upper Gunnison Basin finds itself this year.

So much so, the Bureau of Reclamation faces some timing decisions later this summer and fall in emptying swollen reservoirs along the Gunnison River.

“It’s going to take a lot of work” to reach the winter operating level at Blue Mesa Reservoir, said Erik Knight, lead hydrologist for the Bureau’s Western Colorado Area Office in Grand Junction.

Speaking at Thursday’s quarterly Aspinall Unit Operations meeting, Knight said the reservoir, which Saturday was 98.5 percent full with 817,000 acre feet of water, needs to reach 7,490 elevation by the end of December to avoid icing problems upstream.

The current elevation is 7,518 feet elevation.

“We’re going to be running a lot of water (through Blue Mesa) to meet the Dec. 31 deadline,” Knight said. “But right now our lower reservoirs also are full and Crystal (Dam) is at full power plant release.”

The reason anglers, recreationists and Chamber of Commerce folks have a bank-to-bank Blue Mesa is the result of the late-season storms that blanketed the Upper Gunnison Basin and a cooler-than-normal spring that delayed the runoff.

At last count, inflows into Blue Mesa this year are around 136 percent of normal, and recent rains have continued the inflows.

Also brimming are Crystal Reservoir (88 percent) and Morrow Point Reservoir (98 percent).

Knight said releases out of Crystal are around 1,900 cfs, which is the most possible without spilling the reservoir.

“We have no plans to spill Crystal,” he said.

One beneficiary of all that water is Lake Powell, which currently is 67 feet down or 62 percent full. That level is 17 feet higher than the same time last year but don’t expect Powell to fill much more this year.

Most of the water released by Upper Basin states will be passing through to Lake Mead and then downstream to the Lower Basin and Mexico.

Around 9 million acre-feet of water is expected to be released this summer, more than the 8.25-million acre feet required by the Colorado River Compact and enough to delay concerns about water shortages in Lake Mead.