March precipitation well below normal


Staff Writer

According to a Natural Resources Conservation Service (NRCS) Colorado Snow Survey and Water Supply news release, snowfall in March produced a very slight increase in snowpack in the state of Colorado as a whole.

The exceptions to this are the Gunnison, Upper Rio Grande, San Miguel, Animas, Dolores and San Juan river basins.

“The Gunnison, Upper Rio Grande and the combined San Miguel, Animas, Dolores, and San Juan basins had declines of 3, 11, and 12 percentage points respectively,” a NRCS release read. “In these basins it is likely that they have already reached their peak snowpack for this year and are heading into the melt phase.

“In a typical winter the state receives around 20 percent of its seasonal snow accumulation during March. This winter however, March precipitation recorded at SNOTEL sites was well below normal with the exception of the South Platte and Colorado River basins. With April 8, the average date the snowpack reaches its peak in this state, less than a week away; there is almost no chance that the snowpack will reach normal conditions before beginning to melt.”

The median snowpack in the San Juan Basin is currently 71 percent of average. This is a 4-percent drop from a figure noted on March 5.

Reservoir storage still remains below last year’s and the NRCS predicts a below-average stream runoff this spring and summer.

According to the National Oceanic and Atmospheric Administration (NOAA), the U.S. Seasonal Drought Outlook predicts a drought to persist or intensify.

“Persistence is expected for much of Colorado, New Mexico, Utah, Nevada, and Arizona due to low snow-water equivalent values (around 75 percent of normal) and below average streamflows forecast for the spring and early summer. Enhanced odds for below median precipitation and above normal temperatures during April, May, and June also favor persistence.”

Reservoir storage

As a result of the low snowpack levels, less water is expected to flow in the San Juan River Basin, including the San Juan and Animas rivers.

According to the U.S. Department of Interior Bureau of Reclamation, “the current San Juan River basin snowpack as of March 18th is 79% of average snow water equivalent (SWE). For the Animas River Basin it is 79%. Pending significant changes in the weather and stream flow conditions, the reservoir release will likely remain at reduced levels until further notice.”

As of April 2008, the NRCS described the snow water equivalency as 50-80 percent of normal.

The Climate Prediction Center predicts that precipitation levels in the area will remain below average for the next few months.

Navajo Reservoir releases water through a controlled process. Every year in the spring, if the water is available, the maximum of 5,000 cubic feet per second (cfs) of water is released at the dam (called the “spring peak release”). Due to the relatively dry conditions over the winter, the peak release is not expected to happen this year. Rather than benefitting from the week or two when there is a peak in the release from the reservoir, the San Juan River will be relying on natural snowmelt .

Navajo Reservoir must maintain regular releases in order to maintain a target base outflow of 500 cfs and 1,000 cfs through the endangered fish critical habitat reach of the San Juan River below the dam. These scheduled releases are subject to change due to river flows and weather conditions. At present, a minimum amount of water is being released from the reservoir in order to meet the environmental commitments.

“Our flows in the San Juan River are going to be pretty low,” Susan Behery, hydraulic engineer for the U.S. Bureau of Reclamation explained, “probably somewhat similar to last year. As of right now, we are not planning on having spring peak release in May.”

The runoff flows are low for this time of year and are not expected to be as high as normal in coming months.

On Tuesday, April 23, at 1 p.m., there will be a public meeting regarding Navajo Reservoir operations held at the Civic Center in Farmington, N.M. During this meeting, officials will review the winter’s reservoir operations and plans for the spring and summer, including an open forum for discussion of the operations at Navajo Reservoir. The meeting is open to the public.