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Forecast: McPhee Reservoir likely to fill, provide spill for whitewater boating

Sailing on above-average snowpack, David Wilson of Salt Lake City uses a paraglider to pull him on his snowboard on Lizard Head Pass. (Jim Mimiaga/The Journal)
Above-average snowpack puts farmers and boaters into promising 2023 season

Based on snowpack in the Dolores River Basin, there is a 90% probability that the runoff will fill McPhee Reservoir, according to the Colorado River Basin Forecast Center.

Farmers for the Dolores Water Conservancy District could receive a full irrigation supply of 22 inches per acre, said general manger Ken Curtis, which has not happened since 2019.

“We’re in very good shape for a full supply,” he said. “If it continues to act like winter, that will firm up the forecast.”

According to the Feb. 15 forecast, there is a 70% probability that there will be enough runoff for a small whitewater spill below McPhee Dam for boating in the Lower Dolores River Canyon, according to CRBFC data. The last boating release was in 2019.

At the level of 90% probability, the reservoir would receive 228,000 acre-feet. A full active supply is 225,000 acre-feet, and the reservoir holds 33,000 acre-feet of active supply.

At the 70% probability, as of Feb. 15, the runoff would equal 283,000 acre-feet, which would provide enough water to fill the reservoir and provide for a short boating season below the dam.

A raft enters Snaggletooth Rapid on the Lower Dolores in June. The river came alive last summer after a dam release ended a four-year streak without a rafting season. (Jim Mimiaga/The Journal)

Many variables could shift the forecast up or down.

If winter proceeds at an average level, the forecast would continue to hold up, but abnormally high spring temperatures, consistent wind, and dust on snow could quickly wick away the snowpack.

“The winter could dry out, there could be early spring warming. There is a wide range of possibilities right now,” said Brenda Alcorn, CRBFC senior hydrologist.

The water supply calculation is based on runoff from April through June.

Snotels that measure snowpack in the Dolores River Basin were at 146% of the 30-year average on Feb. 15 for snow-water equivalent, according to data from the National Resources Conservation Service.

Cortez saw precipitation way above average for December and January, said Jim Andrus, weather observer for the National Weather Service.

January received 2.82 inches of precipitation, or 266% of the average 1.06 inches for the month.

December received 1.69 inches of precipitation, or 190% of the average 0.80 inches for the month.

January snowfall for Cortez was 26.8 inches, or 335% of the average 8 inches for the month.

“You can thank the legendary 15-inch snowstorm that hit Jan. 17-18,” Andrus said.

December snowfall was also above average, with 10.2 inches falling, or 138% of the average 7.4 inches.

Snowfall for the winter season, October to April, for Cortez is 44.7 inches, or 173% of average through Feb. 15, Andrus said.

“Now we have spring. Will it eat away at snowpack up high instead of sending it downstream?” he said.