Journal Staff Report

"If" continues to be the key word in forecasting this year’s Dolores River water supply, but no matter what Mother Nature does, McPhee Reservoir will have enough water for all its users this year.

Dolores Water Conservancy District directors discussing the February-October runoff forecast, which is based on snowpack and precipitation readings throughout the watershed, learned at their February meeting that predictions for McPhee range from full to minimum.

According to Bureau of Reclamation engineer Vern Harrell’s "three-ifs" forecast, the most probable water production for the rest of the year is 51 percent of the long-term average, raising the lake’s elevation to about 6,920 feet — about four feet short of capacity — when it reaches its fullest this spring. In order for water to spill into the lower Dolores River below McPhee Dam, the inflow has to be at least 53 percent of normal, Harrell said.

On Feb. 1, the lake surface was at 6,910 elevation. It is expected — at the present "most probable" rate of irrigation, municipal-industrial and downstream use — to be at 6,895 feet at the end of October.

Recent precipitation, in the form of some very wet snow, has brightened the picture somewhat, allowing water managers to revise their predictions upward, although somewhat cautiously. Last weekend’s storm brought .40 of an inch of moisture to the Montezuma Valley and more to the high country, which feeds the runoff.

If, as sometimes happens in the Dolores River watershed, the maximum forecast for February occurs, the runoff would reach 93 percent of average, producing a spring spill of 108,000 acre-feet after the reservoir is full. That scenario would leave the lake at 6,908 feet elevation at the end of the water year, Oct. 31.

"Minimum" runoff, the third "if" in the forecast, would mean the lake surface will continue dropping from its present level and reach about 6,866 feet in elevation by Oct. 31. The permanent pool of the lake is at 6,855 feet.

Dolores Water Conservancy District General Manager John Porter reported that the lower-altitude snow-depth monitoring sites, which have been maintained by the late longtime DWCD board member W.T. "Dopey" Butler for many years, were at 49 percent of normal in water content at the Feb. 1 reading. These units check snowpacks at Groundhog Reservoir, Belmear Mountain, Bald Hill, Willow Springs and the Salter Y, all of which drain into the lake through Beaver Creek.

The four high-altitude Snotels were between 39 and 35 percent of average water content in January and then turned upward to 59 percent in the last part of the month, nearly doubling the water content of the snowpack to about 6 inches when a storm rolled over the area. February precipitation has continued to improve that snowpack.

Comparing the high-Snotel averages, though, Porter said the Feb. 7 reading was the lowest during the second week of February since 1993, the year when averages of all four units were begun. The Lizard Head snow-monitoring station has been operating for 27 years.

Porter said he has been asked when the area begins to build up to its peak snowpack. Presenting a graph of the average Jan. 4-May 5 readings, he noted that the rise was steady but there is no dramatic change until the middle of March when the runoff begins. This is followed by a drop in water content, and then a peak when April storms add to the system. Then the graph shows a considerable drop by the first part of May.

That pattern is fairly typical, Porter said. However, all board members agreed that the entire situation could change dramatically, becoming stormy and wet this spring and providing plenty of water to fill the lake as well as provide a good season for river-rafters and other recreationists.