Colorado River drops to a record-low flow
November 22, 2009
SUMMIT COUNTY – The latest predictions for a mid-winter dry spell may cause some headaches for Colorado water managers as they try to juggle supplies to maintain stream flows and fill reservoirs.
The National Oceanic and Atmospheric Administration is forecasting that a strong El Nino may lead to dry conditions in the state’s northern and central mountains at least until March, based on historic patterns associated with above-normal sea surface temperatures in the eastern Pacific.
Stream flows in Summit County are not too far off seasonal norms, but the Colorado River at Kremmling recently experienced an all-time record low flow for that date, according to local water commissioner Scott Hummer.
The Colorado was only flowing at 280 cubic feet per second on Nov. 16, and flows farther downstream were also well below average, Hummer said. The previous minimum for the date was 330 cfs in 1978.
“I can’t find a rhyme or reason as to why we’re starting to see these low flows so early in the season,” Hummer said.
Statewide, and in the Blue River Basin, the snowpack is at 79 percent of average. Only the Arkansas (at 99 percent) and the South Platte (100 percent) have an average snowpack for the date, he said.
Some of the higher elevation sites in the Blue River Basin have a decent snowpack, including Fremont Pass, where an automated Snotel site shows the snowpack at 121 percent of average. But lower elevation sites are dry, with Summit Ranch, north of Silverthorne, coming in at just 33 percent of normal.
On the upside, reservoir storage around the state is near normal for this time of year.
Hummer said a recent cold spell may have frozen up some of the higher tributaries, a factor that could contribute to low flows. The cold snap was the likely cause of very low flows in the Snake River early this week, Hummer said.
At one point, as Keystone’s snowmaking operation was fully ramped up, the flows in the Snake dropped to only 2 cfs, well below the minimum required stream flow of 6 cfs, set to protect the aquatic environment of the river.
Hummer said resort officials called him about the dip in flows and modified snowmaking operations to prevent a complete dewatering of the Snake.
Keystone is pumping water out of the Roberts Tunnel (which carries water from Dillon Reservoir to the South Platte) to supplement flows in the Snake for snowmaking.
“Keystone Resort acts responsibly and maintains the natural flow of the Snake River during the course of snowmaking,” said resort spokeswoman Kate Coble.
Last month’s temperatures were well below average in the U.S., but globally, it was the sixth-warmest October on record, according to the National Oceanic and Atmospheric Administration.
Based on records dating back to the 1880s, the combined global land and ocean surface temperature for October 2009 was 1.03 degrees below the 20th century average of 57.1 degrees.
The worldwide ocean temperature was the fifth warmest October on record, .9 degrees above the 20th century average of 60.6 degrees.
Warmer-than-average temperatures dominated much of the world’s land areas. The greatest warm temperature variances during October 2009 were present across Alaska and northern and eastern Russia.
Cooler-than-average conditions prevailed across Scandinavia, New Zealand, the contiguous U.S., and parts of northern Australia and southern South America.
Average Arctic sea ice coverage was 2.9 million square miles during October. This is 19.2 percent less than the 1979-2000 average and the second smallest October extent, behind 2007, since record-keeping began in 1979.
Antarctic sea ice extent in October was 1.6 percent above the 1979-2000 average, the ninth largest October extent on record.
Hurricane Rick became the second-most intense northeast Pacific hurricane on record, behind 1997’s Linda, and the strongest hurricane to form in October since reliable records began. Rick made landfall near Mazatlan, Mexico Oct. 21, resulting in two fatalities.