Experts anticipate ‘mediocre’ runoff season
Post Independent Staff
Glenwood Springs, CO Colorado
GLENWOOD SPRINGS, Colorado – The spring runoff season is an exciting time for hydrologists.
“This is our favorite time of year,” said Bryon Lawrence, a hydrologist with the National Oceanic and Atmospheric Administration in Grand Junction. “Because this is when things start to happen.”
However, Lawrence is not too excited about the spring runoff season this year due to a lack of snow accumulation this winter. He said that this year is shaping up to be a “mediocre” runoff year at best.
“The snowpack has been considerably below normal,” he said. “And we are not expecting a really good runoff this year.”
As of Monday, the Colorado River Basin was reportedly at 90 percent of year-to-date precipitation average, according to the Natural Resources Conservation Service.
The recent snowstorms have helped bring the precipitation levels up slightly, but they have not added much to the snowpack, according to Dave Merritt with the Colorado River Water Conservation District.
“They’ve helped somewhat, but it hasn’t changed things much as of [Monday],” Merritt said. “We are still looking pretty dry despite what we are seeing. It hasn’t done that much to the snowpack.”
According to Merritt the area from Grand Lake to Grand Junction remains at 78 percent of average snowpack levels. And statewide, Colorado is at 84 percent of average, he said. Western Colorado is currently at 80 percent of annual snowpack, he said.
The low amount of snowpack will result in a less than average runoff, Lawrence said.
According to the National Weather Service, The Colorado River peaked on May 21 in 2009, running at 10,000 cubic feet per second (CFS) at Dotsero. The average peak runoff for the Colorado River at Dotsero is 9,425 cfs. The weather service predicts the peak runoff to be well below the 2009 levels, at only 4,500 cfs this year at the same location.
“That is less than half of normal,” Lawrence said.
He also expected the peak runoff not to occur until the end of May, or even as late as June 20. However, that is the typical time frame for the runoff to occur, he said.
The National Water Information System real-time water flows used by the United States Geological Survey reported the Colorado River near Dotsero at 1,360 cfs on Monday.
In comparison, this year the Roaring Fork River Basin is currently at 95 percent of average for precipitation. The Roaring Fork River’s peak flow is expected to be about 4,200 cfs, just 300 cfs less than experts are expecting for the Colorado River. However, that is still well below the average peak runoff of 6,150 for the Roaring Fork River.
However, predicting the peak runoff flow is a very slippery slope.
“It’s really difficult to know the day you will see peak flow because it all depends on weather conditions,” Lawrence said.
With warmer weather, peak runoff will occur much more quickly than with lower temperatures.
According to the Bureau of Reclamation, dry conditions for the Upper Colorado River Basin have persisted in 2010. According to the bureau’s website, the Climate Prediction Center estimates that temperatures for May, June and July in the Upper Colorado River Basin are expected to be above average, increasing the pace of runoff. However, precipitation is also expected to be above average for the same time period.
But it may not be enough to bring levels up to sufficient amounts.
“We are seeing deficits anywhere from 2 to 4 inches of precipitation,” Lawrence said. “It’s really hard to make that up.”
The Bureau of Reclamation’s estimates on precipitation for the months thus far in water year 2010, which is measured from October to October, was at 85 percent of annual precipitation levels. November, December, January, February and March had three of the five months at or above annual average precipitation levels, the report stated. December 2009 recorded precipitation levels at 130 percent of average for the Upper Colorado River Basin, but November was at only 40 percent. That left a huge deficit this year that even the recent snow storms won’t be able to make up.
“It’s a little too late,” Lawrence said. “It’s going to take a lot more to make up that deficit, even with what we’ve had.”