The Colorado River Basin looks to be headed for a third straight dry year, according to the April report from the National Oceanic and Atmospheric Administration’s Colorado Basin River Forecast Center.
Although the weather in March was more active than it was in January and February, it continued a trend of either below or well-below normal precipitation across much of the Colorado River Basin, according to Brenda Alcorn, a hydrologist at the NOAA forecast center.
“Thank goodness we had that good December,” Alcorn said Thursday during an online briefing reviewing the agency’s latest monthly water-supply report.
The April NOAA forecast predicts flows to Lake Powell from April through July to be about 64% of average, based on 30 years of data from 1991 to 2020., that prediction called for 98% of average flows to Lake Powell during the same period. Inflows at Powell have been above average in only four of the past 22 years.
There are, however, still a wide range of possible outcomes for how much water will run into Powell this year, Alcorn said. “April and May are important precipitation months, so we’re hoping for better precipitation than we’ve seen recently,” she said during the briefing. “And June and July, too. We still have weather in June and July that can affect us.”
The high end of the prediction for how much water will make its way from the Upper Basin into Lake Powell, according to the forecast, is 6.5 million acre-feet, about average; the lower end is 3.1 million acre-feet. (An acre-foot is the amount of water it takes to cover an acre in a foot of water, or about 326,000 gallons.)
Spring runoff is critical to irrigated agriculture, domestic water supplies, and the recreation industry in Colorado and the West. About 40 million people rely on the Colorado River for household use and farmers and ranchers use water from the river to irrigate more than 3 million acres of farmland.
Jeff Lukas, an independent water and climate researcher based in Lafayette, said the recent NOAA forecast didn’t present any surprises. Rather, he said, it was “solidifying what was already a grim picture” taking shape in early February.
“Three dry years in a row, and two pretty dry years bracketing a really dry year in 2021,” Lukas said. “The trio is as bad as anything we’ve seen since — 2002, 2003 and 2004 would be the worst three on record.”
In the middle of March, Lake Powell fell below 3,525 feet above sea level, a key benchmark for managers because it provides a buffer from the minimum level at which Glen Canyon Dam can generate power. More than 3 million customers use Glen Canyon Dam electricity and the federal government generates more than $150 million in average annual revenue from selling that hydropower.
Less hydropower being generated at dams on the Colorado River system so far this year has forced some.
The National Resources Conservation Service maintains snow telemetry (SNOTEL) sites across the Colorado River Basin, which includes the Colorado River and all the rivers and streams that feed into it. The SNOTEL sites automatically report snow depth and quality. Beginning in December, NOAA produces regular reports based on the data, detailing how that snow might translate into streamflow come spring.
The latest snowpack in Colorado ranges between 82% and 100% of average. In general, the snowpack numbers in Utah and Wyoming are worse. The latest map from the U.S. Drought Monitor shows that about, and about 83% is experiencing some level of drought.
“I’ve settled in that this is where we’re at — we’re looking at 4 million acre-foot runoff,” Lukas said. “We’ve been on this trajectory; at least we’re not falling too much further behind. We still have April and May to go, but at this point I’m just hoping we stay at that level.”