From the Middle Colorado Watershed Council (Dan Ben-Horin) via the Glenwood Springs Post-Independent:
Now that winter is mostly behind us, it’s time to look at our snowpack and make some estimates of what spring runoff may actually look like. The National Weather Service’s Climate Prediction Center (CPC) has forecasted an increased chance for above average precipitation for the entire Upper Colorado River Basin, which is expected given the existing El Niño conditions.
Last year, Miracle May gave our reservoirs a giant boost. Whether that will happen again is still difficult to determine. Recent rains have been a welcome occurrence for the drought-starved Southwestern U.S.: As of May 1, the Colorado snowpack was 111 percent of average. The CPC further reports no signs of any drought development over the next three months and has recommended the removal of the official drought status in the southeastern part of the state.
Over the next month and a half, the Colorado River Water Conservation District will be holding its annual State of the River meetings throughout the Upper Colorado River Basin. Meetings will be held here in Garfield County, as well as in Summit, Mesa, Grand, Eagle and Delta counties. These meetings provide an opportunity for water experts to sketch out how this winter’s snowpack will translate to spring runoff volume and reservoir levels both locally and downstream. With these meetings still a few weeks away, here are some predictions for the larger reservoirs in the Upper Colorado River Basin from the U.S. Bureau of Reclamation:
• Blue Mesa Reservoir: The March flow into Blue Mesa was at 177 percent of average, but forecast inflows over the next three months are all projected to be lower than average, with volumes of 71 percent, 73 percent and 82 percent of average for April, May and June, respectively.
• Flaming Gorge Reservoir: Flaming Gorge saw an inflow at 83 percent of average for the month of March, and inflows for the months of April, May and June are all forecast to be below average, with volumes projected to be 82 percent, 71 percent and 77 percent respectively.
• Navajo Reservoir: March inflow into Navajo was at 90 percent of average. Inflows for the next three months are projected to be below average, with April, May and June forecasted inflow volumes of 70 percent, 79 percent and 72 percent of average, respectively.
• Fontenelle Reservoir: March inflows at Fontenelle on the Green River in southwestern Wyoming totaled 50,000 acre-feet (AF), or 95 percent of the historic average. Daily inflow averages are on the rise with the beginning of spring runoff, with a seven-day average of 1,330 cubic feet per second as of April 14. The Colorado Basin River Forecast Center predicts spring inflows all to be below average. April, May and June forecasted inflow volumes are 82 percent, 67 percent and 84 percent of average respectively.
• Lake Powell: In March, the flow into Lake Powell totaled 553,000 acre-feet, or 83 percent of average. The reservoir elevation is close to the projected seasonal low, and will soon begin increasing as spring runoff enters the reservoir. The April to July 2016 water supply forecast for Lake Powell projects that the most probable inflow volume will be 5.3 million AF, or 74 percent of average. There is much variability in the forecast water supply for the season, with predictions ranging from 3.85 million AF (54 percent of average) to 7.65 million AF (107 percent of average).
While much of the forecasted inflows in the Upper Colorado River Basin are below average, there is still much uncertainty about what the next few months will actually produce. These data come from a report from the Bureau of Reclamation from mid-April, and we are now in a cycle of above normal precipitation. Let’s keep our fingers crossed that this cycle continues well into the spring, swelling our rivers with some much-needed relief for the Southwestern U.S., and putting our Gore-Tex jackets to good use.
Dan Ben-Horin is a watershed specialist with the Middle Colorado Watershed Council. His column, Your Watershed, appears on the second Sunday of each month. The council works to evaluate, protect and enhance the health of the Middle Colorado River Watershed through the cooperative effort of watershed stakeholders. To learn more, go to http://www.midcowatershed.org.
From The Pueblo Chieftain (Matt Hildner):
Dust storms that can accelerate snowpack runoff hit the Rio Grande basin at about an average level this year, although recent snowstorms may have delayed their impact.
“This year is about average,” said Jeff Derry, who heads the Center for Snow and Avalanche Studies in Silverton. “We’ve had about six dust events and all of them, except for one, were pretty moderate.”
Dust layers can ramp up runoff when they emerge at the surface of the snowpack by decreasing the snow’s ability to reflect sunlight.
But Derry said that emergence has been delayed by snowstorms and cloudy skies at the end of April and the beginning of May.
Knowing the extent of dust in the snowpack is important for water managers in the basin trying to stay in compliance with the Rio Grande Compact, which divvies the river’s water between Colorado, New Mexico and Texas.
Without that knowledge, water managers could wrongly interpret the timing and amount of runoff and curtail water users in an attempt to comply with the compact.
“For us — boots on the ground — this is a very big decision-making tool to help us understand why we’re above or below average flows for that day,” Nathan Coombs, who heads the Rio Grande Basin Roundtable, said.
Information about when the dust is about to accelerate runoff also is important to reservoir operators, said Travis Smith.
Smith serves on the Colorado Water Conservation Board and is head of the San Luis Valley Irrigation District, which owns the Rio Grande Reservoir southwest of Creede.
“We want to know as a reservoir operator when the next big inflow is going to happen,” he said.
The center has charted dust storms in the state’s high country for the past 10 years.
Derry said the source of the dust stems from northern Arizona, southern Utah and the Four Corners area where grazing, off-road vehicles, drought and, to a lesser extent, oil and gas development have combined to destabilize the soil.
This year the northern part of the state has gone largely untouched by the dust storms that have hit the San Juans.
Derry said a disparity between the San Juans and the northern part of the state is not uncommon, given the former’s proximity to the source of the dust storms.
“They usually hit the San Juans first,” he said. “They usually hit the San Juans the hardest.”