Cool weather puts spring Yampa River flow on ice in Steamboat
May 6, 2010
Steamboat Springs — The Yampa River was flirting with a record low Wednesday where it flows beneath the Fifth Street Bridge in downtown Steamboat Springs. But the scarcity of water has less to do with the winter's low snowfall total than it does with a cold start to spring.
The Yampa was flowing at just 320 cubic feet per second at 2:15 p.m. Wednesday, compared with the median flow for this date of 1,170 cfs, which is based on 100 years of record.
The all-time low for May 5 is 317 cfs.
"We got a first flush of runoff a couple of weeks ago, but we've had cold temperatures," Joe Sullivan said. "If it stays cool, we'll just have a slow runoff. Either way, it seems like it will be below average this year."
Sullivan is a supervisory hydrologic technician with the U.S. Geological Survey office in Grand Junction. His office tracks stream flow on Colorado's Western Slope. The USGS uses stream flow gauges at key junctures along rivers all across the country. Readers can follow the ups and downs of the runoff in the Yampa where it flows through town here.
A tab at the top of the page makes it possible to link to rivers all across Colorado and other states through interactive maps.
While the USGS records stream flow, another federal agency, the National Oceanic and Atmospheric Administration, at its Colorado Basin River Forecast Center in Salt Lake City, uses stream flow data and historical climate data to project when and how high Western rivers might peak. The information helps reservoir managers anticipate how quickly their impoundments will fill, municipal water managers to plan for lawn irrigation restrictions, and farmers and ranchers to get a feel for how much water they may be able to access to irrigate their fields.
"We really don't know what's going to happen on the Yampa, but we're projecting it could peak as low as 1,150 cfs and as high as 2,950 cfs," said Craig Peterson, a senior hydrometeorologist with NOAA. "And while it seems unlikely this year, we could have a significant peak, especially if we continue to hold the melt. We're projecting a 50/50 chance that it will peak at 2,050 cfs."
Even the high projection of 2,950 this year would not reach the average annual peak flow for the Fifth Street measuring station, 3,240 cfs.
Peterson explained that the deeper cool temperatures prevail into spring, the more likely it becomes that the weather could change to a summer pattern as if someone had flipped a switch. That could result in a short, intense runoff, particularly if a warm rain contributed to the snowmelt, he said.
Readers can look at the latest NOAA projections issued April 1 for major rivers in Colorado, Wyoming and Utah here.
Peterson said that as of April 1, his office was projecting that the Yampa at Steamboat would peak between May 19 and June 12. Projections are based on 30 years of temperature and precipitation data, he said.
The historic high stream flow peak for the Yampa at Fifth Street is 5,870 cfs. Flood stage is 4,700 cfs.
Last spring served as an example of how weather influences peak stream flows even after a big snow year. Steamboat Ski Area reported 405 inches of snowfall at mid-mountain for the winter of 2008-09. However, the river where it flows through town peaked below its average at 2,880 cfs on May 25, 2009, according to NOAA. The ski area tallied 261 inches of snow during the 2009-10 season.
The water stored in the accumulated snow on Rabbit Ears Pass stood at 17.1 inches Wednesday, up 1.5 inches from April 30. However, that number represented just 58 percent of the 29.3 inches of water typically stored on the pass at this date.
Runoff will set in for real on the Yampa, Sullivan said, when overnight temperatures at high elevations remain well above freezing, ending the daily spring freeze/thaw cycle.
— To reach Tom Ross, call 871-4205 or e-mail firstname.lastname@example.org