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Early winter snowpack a good sign for McPhee Reservoir

Dolores and McPhee Reservoir are having a good winter so far. (Jim Mimiaga/The Journal)
Snotels are 130% of average for Dolores-San Miguel Basins

Above-average snowpack in the San Juan Mountains has McPhee Reservoir managers and farmers feeling optimistic for the 2023 irrigation season.

Ten days of snowstorms was the difference-maker.

Snowpack for the Dolores and San Miguel Basins shot up to 130% on Jan. 3, up from 64% of average on Dec. 26.

The Dolores River Basin feeds McPhee Reservoir.

Snotels that measure snowfall for the Dolores drainage showed averages of 127% at Lizard Head Pass, 174% for Scotch Creek, 115% at Sharkstooth, and 140% at El Diente Peak.

“We are doing really well, but (a full supply) still depends on the next three months,” said Ken Curtis, general manager for the Dolores Water Conservancy District, which manages McPhee.

Translated into runoff, the current Dolores River snowpack would generate about half of McPhee’s active supply, he said.

Because of drought, McPhee has not filled the past three years, including 10% supply in 2021 and 40% supply in 2022.

Cortez saw above average precipitation for December thanks to recent snowstorms. (Jim Mimiaga/The Journal)
Cortez saw heavy snow and snowpacked streets early Tuesday morning. (Jim Mimiaga/The Journal)
This avalanche is estimated to have released naturally on Dec. 31 above the Ophir Pass Road from south-facing terrain. (Courtesy Colorado Avalanche Information Center)
Cortez was digging out Tuesday morning after a snowstorm. (Jim Mimiaga/The Journal)
Montezuma County crews were plowing parking lots Tuesday morning. (Jim Mimiaga/The Journal)

Warm winter days in December has allowed the Dolores River to start filling McPhee, Curtis said.

While the stream gauge is frozen, reservoir managers can estimate flow from how much the reservoir has been rising.

In December, flows ranged from 25 cubic feet per second to 100 cfs and generated 3,000 acre-feet for the lake for the month.

Currently McPhee has about 36,000 acre-feet of irrigation storage, which will also help fill adjacent Narraguinnep Reservoir, owned by the Montezuma Valley Irrigation Co. Full supply for McPhee is about 225,000 acre-feet.

“It is a good cushion, we’re not playing catch-up at this point,” Curtis said. “Even with average snow the next three months, we would be doing well. The potential is there. We’ll keep monitoring.”

Farmers are not quite ready to make financial decisions for the 2023 season, such as seed and fertilizer purchases.

The first preliminary runoff predictions by the Colorado River Basin Forecast Center are expected to come out this week. Irrigation supply for farmers gets more clear in March.

A decent summer monsoon season is expected to aid runoff into McPhee Reservoir. Going into winter, good soil moisture allows snow to melt off into the creeks and rivers in the spring instead of being absorbed by the soil, although a dry November could decrease the benefit somewhat.

The snowstorms dumped in the high country and hit lower elevations as well.

That is especially promising for dry land winter wheat farmers who plant in the fall and depend on natural soil moisture for the crop to mature in the spring.

Storms benefit high and low

The recent snowstorms were wide ranging across Southwest Colorado, said meteorologist Kris Sanders, of the National Weather Service in Grand Junction.

Snow totals from Dec. 26 to Jan. 3 are: Cortez, 9.5 inches; Lewis, 11.5 inches; Dove Creek, 16.5 inches; south of Rico, 23 inches; Durango, 19 inches; Hesperus Hill, 30 inches; and Towaoc and Ignacio, 4 to 10 inches.

An atmospheric river from the Pacific generated the heavy, wet snowfall, sleet and rain. Warmer air with the storm front produced rain up to 9,000 feet elevation.

“It was a ribbon of moisture that produced some big numbers with several waves coming through,” Sanders said.

Thanks to the late-year storms, Cortez was above normal precipitation for December, coming in at 1.53 inches, or 171% of average for the month of 0.89 inches.

Cortez made a valiant effort for an average precipitation for 2022, coming in at 10.02 inches, or 86% of yearly average of 11.66 inches.

Cortez will dry out on Wednesday with mostly sunny skies, according to the forecast. A smaller storm may bring moisture Thursday and Friday, the weekend looks dry and mostly sunny with a high of 38 degrees.