A Decent Winter Becomes A Lousy Spring On The #RioGrande — #NewMexico in Focus #snowpack #runoff

From New Mexico in Focus (Laura Paskus):

This spring, the Rio Grande through Albuquerque is running at about 20 percent of its historic average—even though snowpack in the watershed was close to average last fall and into February. Conditions won’t get much better: Peak snowmelt occurred last week, according to the U.S. Bureau of Reclamation.

“This year was more along the lines of what I anticipate for the future, to happen more often,” says David Gutzler, professor of Earth and Planetary Sciences at the University of New Mexico. Gutzler has been studying climate change in the southwestern United States for decades.

Increasingly warm conditions play out in predictable ways in the arid Southwest. That includes having less water in rivers, even when the region isn’t necessarily mired in drought, experiencing a deficit in snowpack or rainfall.

“You get snow in the winter when it’s really cold, but then things get warm and dry—which is the long-term outlook for springtime in the Southwest—and the snow just melts away faster than our historical statistics would suggest,” Gutzler says of this year’s conditions.

“This is more like a global warming-style of a low streamflow year, as opposed to a drought year [like 2018] that started off bad and stayed warm, and was just bad for the whole winter.”

Two years ago, then-UNM graduate student Shaleene Chavarria published her research with Gutzler about declining snowmelt and streamflows in the Rio Grande. In that peer-reviewed study, she looked at annual and monthly changes in climate variables and streamflow volume in the headwaters of the Rio Grande in Colorado between 1958 and 2015. She found that flows are declining in March, April, and May.

Chavarria, a hydrologist, saw something else in the records: Snowpack in the Rio Grande watershed is decreasing. And it’s melting earlier.

That’s definitely playing out again this year.

Looking at the data, Chavarria notes that in 2018 and 2020, snowpack melted out about a month earlier than it normally did in the past. “This is something we address in the paper, and I think it’s interesting and scary to see it happening,” she wrote in an email to NMPBS…

The changes in the timing of spring runoff and in the amount of water flowing within the banks of the Rio Grande affect farmers and cities. They also affect the river’s ecosystem—including the cottonwood bosque—and the species that depend upon its waters and cycles.

Already, according to Carolyn Donnelly with the U.S. Bureau of Reclamation, the water management agency has released about 4,000 acre feet of water from upstream reservoirs to prevent riverbed drying—and it plans to release supplemental water again within the week.

When the Natural Resources Conservation Service released its final May streamflow this week, the numbers were “pretty grim,” says Reclamation spokesperson Mary Carlson.

“In March, we were looking at a runoff that was near average. But that just didn’t materialize,” Carlson says. “We will continue to coordinate closely with our water operations partners to ensure that every drop of the supply that we do have will be used in the most beneficial way.”

She adds that New Mexico will likely end up under Article VII restrictions by the middle of June.

Under that provision of the Rio Grande Compact of 1938, New Mexico is only allowed to store water in upstream reservoirs when levels in Elephant Butte Reservoir are above a certain threshold. With little water flowing into that reservoir this year, the state won’t be able to store waters upstream—and Elephant Butte’s levels will keep dropping, too.

The bureau anticipates Elephant Butte’s levels will drop close to its 2018 historic lows, when the reservoir was at just three percent of capacity. (The reservoir, which was built to hold two million acre feet of water, is about 25 percent full this week. Water stored there is allocated to farmers in southern New Mexico and Texas)

Reclamation also anticipates that the Middle Rio Grande will dry within the next month, beginning within Bosque del Apache National Wildlife Refuge in San Antonio…

Upper Rio Grande River Basin High/Low graph May 7, 2020 via the NRCS.

For decades, the U.S. Fish and Wildlife Service, along with federal, state, tribal, and local partners, has tried to keep the endangered Rio Grande silvery minnow from going extinct. The two-inch long fish was once one of the river’s most abundant. But by the 1990s, its population had plummeted, earning it the dubious distinction of requiring federal protection under the Endangered Species Act. Some of those efforts include releasing water to keep the river flowing longer, and also working with the Middle Rio Grande Conservancy District to release water “spikes” when the minnows are spawning.

When the Middle Rio Grande does dry, as it has many summers since the 1990s, biologists end up in the riverbed, trying to salvage what live minnows they can find. They scoop the fish from pools and puddles, then transport them to sections of the river where flows are high enough to possibly sustain the tiny fish.

Fish and Wildlife Service biologist Thomas Archdeacon anticipates the river will dry around Memorial Day. When that starts happening, biologists will slog through the muddy—and then sandy—riverbed, seeking out the endangered fish.

Rio Grande Silvery Minnow via Wikipedia

Variable April Precipitation Widens Differences in Streamflow Forecasts — NRCS #runoff #snowpack

Here’s the release from the NRCS (Brian Domonkos):

The month of April brought below average precipitation across all of Colorado with extremely dry conditions in southern Colorado in particular. All major basins in the southern half of the state received less than 50 percent of average precipitation with the Rio Grande at the bottom of the list with a meager 16 percent of average. Most SNOTEL sites in the San Juan and Sangre de Cristo Mountains recorded the lowest or second lowest April precipitation on record. The basins of northern Colorado all received between 77 and 84 percent of average precipitation. “The precipitation differences across the state have caused notable changes to streamflow forecasts across the state since the beginning of April. Considerable declines in streamflow forecasts were observed across southern Colorado over the last month,” states NRCS Hydrologist Karl Wetlaufer. On average streamflow forecasts dropped 10-15 percent in the Rio Grande and combined San Miguel, Dolores, Animas, and San Juan basins and more in some southern tributaries to the Arkansas.

In addition to the past month the 2020 water supply situation is further complicated by conditions leading into the winter season. The late summer and fall of 2019 was also extremely dry leading to very low soil moisture conditions going into winter which can have an effect on the efficiency of snowmelt runoff. Wetlaufer notes that “Dry soils underlying the snowpack can absorb much of the snowmelt in the spring which has the potential to substantially decrease the amount of water that actually makes it to a stream channel to contribute to runoff”. Because of this effect it is anticipated that streamflows will be less than are commonly observed in other years with a similar snowpack peak and particularly in the southern half of the state. Statewide snowpack peaked on April 4th at 103 percent of normal but snowpack accumulation and melt patterns varied widely across the state after that point.

Reservoir storage has not varied widely this water year and statewide storage remains near normal at 104 percent of average. The largest monthly change was observed in the combined San Miguel, Dolores, Animas, and San Juan basins with a 9 percent drop bringing it down to 95 percent of average storage. Recent warm temperatures have been driving accelerated snowmelt which has been helping increase reservoir storage over the last two weeks but that could also lead to an early streamflow peak making that storage more important later in the summer.

So far water year 2020 has been a roller coaster of conditions through time and across the state and the last month has been no different. Given the unique nature of water supply conditions across the state and future weather uncertainty, it will be worth keeping a close eye on changes over the coming months.

Expected spring #runoff into #ColoradoRiver plunges after dry April — Tucson.com

Graphic credit: Colorado River Basin Forecast Center
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From Tucson.com (Tony Davis):

May’s monthly runoff prediction for the April-through-July period was 65% of average, or 4.6 million acre-feet. That’s 1 million acre-feet less than the April forecast predicted. Tucson Water customers typically use close to 100,000 acre-feet a year.

While low runoff this year is highly unlikely to trigger the river’s first major shortage as soon as 2021, it raises the possibility of one in 2022. A shortage would fall particularly hard on Central Arizona farmers. Flows of water into Powell that would be low enough to cause a shortage in 2022 are likely to occur about 10% of the time, said the U.S. Bureau of Reclamation’s most recent study of its reservoir operations, published in mid-April.

“This could be the start of a multi-year drought. Last year was a wet year, so one year like this we can handle,” said Eric Kuhn, a retired general manager of a northern Colorado water district and author of a recent book on the river. “One dry year doesn’t usually make a difference if we start in good shape. Two dry years or three dry years is a concern.”

The dry April weather wiped out the benefits of a robust winter snowpack in Upper Colorado River Basin states, federal forecasters said this week. Until now, this year’s forecast had been relatively stable, ranging from 74% to 82% of average runoff since January…

But Brenda Alcorn, a hydrologist for the federal Colorado Basin River Forecast Center, said that if the dry spell continues, the eventual runoff could well end up lower than what’s now predicted.

It could possibly fall as low as or lower than the 2018 runoff of 36% of normal, “if we have extreme dryness through the rest of the spring,” Alcorn said.

Since the mid-2010s, the Colorado’s spring-summer runoff has done “a lot of yo-yoing,” Alcorn said.

The runoff rose sharply in 2017, fell sharply in 2018 and soared to 145% of the average runoff in 2019.

While these fluctuations have staved off the shortages that most water experts now view as inevitable, the river is clearly more vulnerable to shortages than it was in 2000, when both Lakes Mead and Powell were full or nearly full.

Today, Lake Mead is 44% full, and Lake Powell is at 48%…

This latest bad spring-summer river runoff forecast, however, stemmed largely from dry, not hot weather, the Colorado Basin River Forecast Center said.

“April precipitation was generally below to much below average across the Colorado River Basin and Great Basin,” the center said in a report on its latest forecast. “It was exceptionally dry over northern Utah and southwest Colorado.”

A number of sites that measure snowpack in Utah and southwest Colorado showed their lowest April precipitation since officials started recording it up to 35 years ago…

April river flows neared record lows in parts of the Gunnison, Dolores and San Juan river basins in the two states.

April temperatures across the basin were generally near the average. Temperatures fell below average for the first three weeks of the month.

#Runoff news: Much of the #ArkansasRiver above Lake Pueblo is currently runnable

Browns Canyon via BrownsCanyon.org

From The Mountain Mail (Cody Olivas):

Nearly the entire [Arkansas River], from Granite all the way to the Pueblo Whitewater Park, is flowing at or above 700 cubic feet per second, the level of flow that Colorado Parks and Wildlife maintains for boating from July 1 to Aug. 15 with its voluntary flow management program.

The river was flowing at 696 cfs Wednesday from Granite to Buena Vista. From Buena Vista to Rincon it was flowing at 1,080 cfs, then at 911 cfs to Cañon City and 665 CFS at Pueblo’s water park.

“It seems runoff typically begins between May 1 and May 15,” Rob White, Arkansas Headwaters Recreation Area park manager, said. “It started a little early this year.”

He said he thinks the whole river is currently runnable, and signs are pointing to a good season.

“It appears like it’s going to be a pretty good whitewater season in terms of water,” White said. He said it will depend on how hot it gets as well as how much rain falls, but he noted that with the upper basin’s SNOTEL sites currently above 100 percent, water levels could be above average this season.

From Steamboat Today (Derek Maiolo):

On Monday, the flow of the Yampa River had risen to more than 2,000 cubic feet per second, according to data from the U.S. Geological Survey. The flow has decreased slightly since then, due mainly to fluctuations in snow melt and temperature.

Portions of the Yampa River Core Trail have been closed due to high water, according to Craig Robinson, parks open space and trail manager for Steamboat Springs Parks and Recreation. Signs have been posted in those areas directing people to detours. Most of the trail closures are on underpasses, Robinson said…

The Yampa River likely will continue to rise and flow at faster rates in the coming weeks, according to Tom Martindale, streets supervisor for the city of Steamboat Springs. The river usually peaks in late May or early June, he said. This comes after snowpack reaches its peak in the higher elevations and warmer temperatures send the melted snow downstream.

The smaller tributaries that feed into the Yampa River likely have reached or neared their peak levels, Martindale added. He regularly surveys Butcherknife Creek and Soda Creek, checking also for any debris, such as trees, that could dam the waterways and lead to flooding. So far, he has not seen any major issues…

The city currently is offering sand and sandbags for residents who want to fortify their homes against flooding. As of Tuesday, the city had set up two collection sites: one at Missouri Avenue and North Park Road, the other at Short and James streets. A third site at Eighth Street and Crawford Avenue will be established this week, Martindale said.

Uncompahgre River Valley looking south

From The Montrose Press (Katharhynn Heidelberg):

Although snow was nearly average through December, it fell to below average for January and February in the Gunnison Basin, then bounced back close to average in March and hit between 90 to 95 percent of average in April, according to the U.S. Bureau of Reclamation, which manages the Aspinall Unit.

Moderate drought conditions persist throughout the basin.

As of last week, snow conditions in the basin sat just below average, with runoff forecast for the rivers 70 to 80 percent of average. The forecast puts the unit in the “moderately dry” year hydrologic category and if that holds, it will call for a one-day peak flow of 7,017 cubic feet per second in the lower Gunnison, as measured at the Whitewater gauge, according to written information from BuRec.

There are no half-bankfull or peak flow duration targets under this type of hydrologic year.

Flows on the Gunnison through the Black Canyon are projected to peak at nearly 4,000 cubic feet per second. After peak, the flows will likely drop to between 500 and 900 cfs and the baseflow targets at the Whitewater gauge, consistent with moderately dry years, are to be between 890 and 1,050 cfs (summer).

Blue Mesa Reservoir was sitting at 515,000 acre-feet and is forecast to hit a maximum content of 730,000 acre-feet by late June, or about 11 feet below what would be a full reservoir, per BuRec.

The reservoir would then slowly decrease to its winter target level of 580,000 acre feet. Black Canyon flows are projected to drop to 400 cfs by early fall, according to BuRec’s report…

Overall precipitation has been “well below normal” since the start of the water year and moderate drought conditions are predicted in most of the basin. The start of the month could bring below normal precipitation and above-normal temperatures — it is expected to be both warmer and drier…

“The snowpack is disappointing, there’s no doubt about that,” Anderson said. The UVWUA experienced an April “hole” this year, when less snow and colder weather in the high country meant there was not enough water to feed the project and the association had to dip into its storage at Ridgway and Taylor Park reservoirs.

However, the UVWUA had full accounts there going into April.

“Currently, we’re not using any storage and that’s a good thing. We still have plenty to make the irrigation season,” Anderson said.