Snowfall boosts hopes for beginning of end of drought
BRECKENRIDGE – Last month’s record snowfall was a welcome relief to those fretting about another dry summer, but the water it brought won’t be enough to refill reservoirs throughout the state.
Currently, Dillon Reservoir, which is owned by Denver Water, is 47 percent full. But statewide, all the reservoirs owned by Denver Water are 43 percent of average – and two are completely empty.
“We’re in a lot better position than I thought we would be two months ago,” said Scott Hummer, water commissioner for the Upper Blue Basin. “It behooves us to keep in mind that reservoir levels are low, streamflows are low, and there’s still a long time to go between April 1 and when the snow flies in October. We still have to be diligent as far as water conservation goes. We are by no means at the end of the drought.”
Water experts use a three-tier system to evaluate droughts. Forecasters use meteorological guidelines, and, Hummer said, would say the drought is over because Colorado will be close to having 100 percent snowpack by April 1.
Hydrologic drought relates to reservoir storage, which is considerably below normal.
“We’re at one year of normal,” Hummer said of snowpack. “It’s still going to take three years of normal to get to full. Things have yet to play out, but it looks like it may bode well for us right now.”
Agricultural drought relates to the how much water is available to farmers who get their water either from streams or wells.
Snowpack at Summit County’s Snotel sites indicates snowpack and the water within it is above average, 106 percent and 115 percent, respectively. A month ago, Upper Colorado snowpack levels were 90 percent of normal.
Snotel sites throughout the state measure snowfall, precipitation and temperatures to help water experts determine how much runoff might be expected in any given year.
Statewide, snowpack is 95 percent of average. The recent snowfall – which some say was the largest blizzard in 90 years – boosted snowpack in all of Colorado’s eight river basins except the Yampa and White River basins, where snowpack remained at 90 percent of average. The South Platte basin saw the biggest improvement, from 81 percent of normal to 111 percent of normal.
Snowpack and the water within it varies widely, even within basins, Hummer noted. For example, the Snotel site at Wolf Creek Summit has 21.6 inches of water in its snowpack; the 30-year average is 33.1 inches making Monday’s average 65 percent of normal. Wolf Creek Pass – typically the snowiest place in the state – usually gets 5.9 inches of water in its snowpack. Monday, it measured zero. In between the two sites, at Ute Creek, water currently measures 16.3 inches, and the 30-year average is 8.1 inches.
Historically, 80 percent of the water collected in the state’s rivers and reservoirs comes from late winter and early spring snow and rain.
According to Hummer, 75 cubic feet per second (cfs) of water is flowing into Dillon Reservoir from the Blue, Tenmile and Snake rivers.
But a call change at the Shoshone Water Plant near Glenwood Springs Saturday reduced the water flow there to 660 cfs. Normally, the Shoshone plant can demand up to 1,250 cfs water from upstream reservoirs, Hummer said. Under a deal forged late last month between Denver Water and the power facility, that amount has been changed to 700 cfs until May 23.
So anytime the flow into the Shoshone falls below 700 cfs, water agreements require that upper reservoirs, including Dillon Reservoir, must allow instream flows to pass through to the Colorado River. Once those numbers reach 700 cfs, upper reservoirs can cut back the amount of water they allow to pass through and start storing water.
The minimum amount of water that must be released from the Dillon Dam is 50 cfs. But Denver Water, which owns the dam and the water behind it, also diverts water for its municipal uses through the Roberts Tunnel. The Roberts Tunnel diverts water from Dillon Reservoir, near the Dillon Peninsula, over the Continental Divide to Grant. From there it flows downstream in the South Platte River to Denver. Monday, the Roberts Tunnel was essentially closed, with Denver Water diverting 1.92 cfs, Hummer said.
“I think we’re seeing about as much snowpack as we’re going to see,” Hummer said. “If the summer plays out like it normally does, we’ll see the runoff happen. But because of low reservoir storage, we’ll have to see how July, August, September plays out.”
Jane Stebbins can be reached at (970) 668-3998 ext. 228 or firstname.lastname@example.org.
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