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Water managers see runoff as positive sign

Heading into summer, forecasts aren’t great, but they are slightly better than last year
Vallecito Reservoir is partially full Thursday and is not expected to reach full capacity after snowmelt in the mountains this year. Runoff in Southwest Colorado is two to three weeks early this year because of the warmer temperatures and dust events, said Susan Behery, a hydraulic engineer with the U.S. Bureau of Reclamation. (Jerry McBride/Durango Herald)

As rivers begin to swell with spring runoff, water managers in Southwest Colorado feel optimistic that this year will be better than the last.

Water forecasts remain below average, but above last year’s troubling lows – a positive sign for water managers adapting to sustained drought in the region. Yet, much will depend on the impact of recent dust events and summer monsoons.

The remaining snow is seen on the La Plata Mountains on Wednesday. (Jerry McBride/Durango Herald)

“We were showing there’d been some snowmelt, but we were still sitting fairly good on snowpack. Runoff estimates, depending on where you were looking, were 60 to 70% of average,” Steve Wolff, general manager for the Southwestern Water Conservation District, said of early April forecasts.

According to SNOTEL data from the U.S. Department of Agriculture’s National Resources Conservation Service, a little more than half of the snowpack in the San Miguel, Dolores, Animas and San Juan basins has melted so far. Snowpack is measured using the metric of snow water equivalent, or the water content of the snow.

The Animas River was flowing at 669 cubic feet per second in Durango on Wednesday afternoon, the Dolores River at 556 cfs in Dolores and the San Juan River at 895 cfs, according to Colorado Basin River Forecast Center data.

Southwest Colorado’s rivers have slowed since Friday, but the Colorado Basin River Forecast Center predicts that flows will again increase over the next week and a half.

Forecasts show the Animas River will peak at 3,100 cfs in late May or early June, slightly above last year’s peak of 2,910 cfs on June 7. Forecasts project peaks of 1,500 cfs for the Dolores River and 1,600 cfs for the San Juan River also in late May and early June.

A graph showing the snowpack in the San Miguel, Dolores, Animas and San Juan basins on Wednesday. Snowpack is a little more than halfway gone in Southwest Colorado. (U.S. Department of Agriculture/Natural Resources Conservation Service)

Snow is melting earlier than average this year, according to the SNOTEL data, a trend that Wolff and other water managers have noted. Typically, snowpack would peak around April 1 and runoff would last from April through May and even into June, Wolff said.

“Runoff is coming earlier these days than we used to see, so I’m not sure there is a normal anymore,” he said. “We are seeing snowmelt begin earlier in the season and I think that will be a continuing trend.”

While runoff is happening earlier this year, water supply forecasts suggest more optimism. The Animas, Dolores and San Juan rivers are hovering just above 70% of average, according to Colorado Basin River Forecast Center forecasts.

“It’s certainly better than last year. (We’ve seen) decent snowpack. We are seeing relatively decent water supplies come off,” Wolff said.

Forecasts also show reservoirs below average, ranging from 53% of average at McPhee Reservoir in Dolores to 72% at Vallecito Reservoir. But for McPhee Reservoir that is a sharp departure from the historic low of 32% projected last year.

Vallecito Reservoir’s water level is about 72% of average for this time of year. (Jerry McBride/Durango Herald)

Ken Curtis, general manager for the Dolores Water Conservancy District, told Wolff the district was hoping to get at least 70% of its average water.

“They got 10% last year. If they get 70%, or maybe even a little more than that this year, that’s pretty good news,” Wolff said.

Rob Genualdi, division engineer for Southwest Colorado’s Division 7 of the Colorado Division of Water Resources, said none of the local reservoirs will likely fill completely.

Kevin Hronich, president of the Pine River Conservation District, echoed that assessment for Vallecito Reservoir, which he said will not reach its average. Vallecito Reservoir will reach about the same level as last year when it was 71% of average, he said.

“If we can get some monsoonal moisture, we’re going to be about the same as last year. Still well below average, but at this point that’s better than not as good,” he said.

While the water outlook for the region is positive, Hronich, Wolff and Genualdi each said a successful summer will depend on monsoon rains to supplement this year’s snowpack and sustain water resources.

“We absolutely need some rain this summer to get us through,” Hronich said. “A reasonable goal for the Pine River Irrigation District out of Vallecito is if we can have irrigating water through Sept. 15. But there’s no way we’ll get there unless we get some summer rain. We will just flat be out of water by the first part of August if we don’t see some monsoonal moisture.”

The other concern for water managers is the high winds and dust events that have happened the last few weeks.

Forecasts show the Animas River will peak at 3,100 cubic feet per second in late May or early June, slightly above last year’s peak of 2,910 cfs on June 7. Forecasts project peaks of 1,500 cfs for the Dolores River and 1,600 cfs for the San Juan River also in late May and early June. (Jerry McBride/Durango Herald file)

Wolff said he was curious to know about the impact of recent dust-on-snow events on runoff, but he didn’t have a good idea of how much faster those dust events would make snowpack melt.

In his most recent update released Monday, Jeff Derry, executive director for the Center of Snow and Avalanche Studies and the lead on the Colorado Dust-on-Snow program, documented a one-day decrease of 17% in the snow’s albedo at a monitoring site at Red Mountain Pass.

A lower albedo, a measure of the snow’s reflectance, results in snow melting faster, and Southwest Colorado will likely see earlier snowmelt this year because of the dust events, Derry said.

Southwest Colorado has had seven dust events so far this season, according to Derry’s update.

“It’s just been windy everywhere across the state more so than the usual spring winds, and that’s really done a number for wildfires and dust,” he said.

Susan Behery, a hydraulic engineer with the U.S. Bureau of Reclamation, attributed the early snowmelt this year in part to the dust.

“We’ve had what I consider an average snow year, but all of the SNOTELs are melting off anywhere between two and three weeks early,” Behery said. “A lot of that is due to warm temperatures, and then some of it is due to the really intense and severe dust events that we've had lately.”

Dry soils from years of drought have resulted in less runoff, too, she said.

“Even though we had average snowpack, we’re probably looking at a well-below average inflow season,” she said.

Vallecito Reservoir will reach about the same level as last year when it was 71% of average. “We absolutely need some rain this summer to get us through,” said Kevin Hronich, president of the Pine River Conservation District. “A reasonable goal for the Pine River Irrigation District out of Vallecito is if we can have irrigating water through Sept. 15. But there’s no way we’ll get there unless we get some summer rain.” (Jerry McBride/Durango Herald)

While water managers maintain hope that early season forecasts for Southwest Colorado will result in a comparable or better water year than 2021, elsewhere in the Upper Colorado River Basin the forecasts are less promising.

“It’s pretty grim. There’s maybe a few sites in the Upper Colorado that are forecast to be near normal, but almost everywhere we’re forecasting and expecting below-normal runoff,” said Cody Moser, a senior hydrologist with the Colorado Basin River Forecast Center.

As of Wednesday, the entirety of Southwest Colorado was in drought, ranging from moderate throughout La Plata, Archuleta, Hinsdale, Dolores, San Juan, San Miguel and Ouray counties to severe and extreme in parts of Montezuma County.

“I think we’re going to struggle through another drought year,” Behery said. “I’m hoping for a good monsoon season because we really do need some sustained above-average monsoons to overcome the soil moisture deficit.”

ahannon@durangoherald.com

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