Ruedi Reservoir at lowest level in two decades

Ruedi Reservoir is at about its lowest level of the year — and also of the past 19 years — according to numbers from the Bureau of Reclamation.

As of Wednesday, the reservoir on the Fryingpan River contained 54,914 acre-feet of water and was about 54% full. And according to U.S. Bureau of Reclamation data, outflow is currently slightly more than inflow, meaning levels may not have bottomed out yet.

The last time the level was this low was in the drought year of 2003 when Ruedi hit 46,117 acre-feet, according to Timothy Miller, a hydrologist with Reclamation, which operates the reservoir. Many reservoirs across the West are at their lowest levels of the year right before spring runoff starts, and water managers will start to see in the next month what this year will bring and whether it’s enough to fill depleted storage buckets.

Despite the current low levels, Miller said forecasts show Ruedi should be able to fill this year — but just barely. The most recent forecast from the Colorado Basin River Forecast Center shows that spring inflow for Ruedi will be about 96% of average.

“If we continue to get average precipitation, we should be able to fill by the skin of our teeth,” he said. “We won’t have any extra water. It’s going to be a tight fill.”

In 2021, Ruedi, which has a capacity of about 102,000 acre-feet, was only about 80% full after spring runoff.

“April hole”

Something that may influence if and how Ruedi fills this year is a phenomenon called the “April hole.” Agricultural irrigators downstream in the Grand Valley usually begin filling their ditches around April 1, and if irrigation ramps up faster than the snow melts in the high country, there may not be enough water to meet their demand.

Grand Valley irrigators, with large senior water rights dating to 1912, can command the entire Colorado River and its tributaries in western Colorado by placing a call. This means water users with junior water rights have to stop taking water so that the Grand Valley irrigators can get their entire amount of water to which they are entitled. When these irrigators put a call on the river, known as the “Cameo call,” it can control all junior water rights upstream of their diversion at the roller dam in DeBeque Canyon.

The Cameo call doesn’t come in April of every year, but it did in 2021 and lasted for 16 days — the longest April hole ever. Dry soils and hot temperatures in 2020 and 2021, fueled by climate change and drought, robbed the river of flows and created conditions never before seen by water managers.

“Last year was definitely the extreme,” said James Heath, Division 5 Engineer for the Colorado Division of Water Resources. “We never had a call in April last that long. The prior longest was in 2002, with five days of call.”

Instead of curbing their water use when the Cameo call is on, some water users simply release water from Ruedi that they have bought and store there as part of an augmentation plan. The problem, Heath said, is that many of these water replacement plans counted on a call lasting at most seven days.

“What we are finding is a lot of the plans were originally decreed for a worst-case call scenario of seven days in April,” he said. “Last year, they were diverting out of priority and injuring the downstream water rights.”

Heath said his office is still figuring out how to address these shortfalls and analyze different entities’ augmentation plans. He said Ruedi had to release about 1,300 acre-feet of water last year to satisfy the Cameo call in April.

Hydropower production

A consequence of low levels in Ruedi is a reduced capacity to generate power at the hydroelectric plant, which is operated by the city of Aspen. Steve Hunter, utilities resource manager with the city, said the bottom line is this: the less water, the less power that is able to be produced.

Hunter said if water levels fall below 7,700 feet elevation, utilities staff may decide to shut the unit off because the water pressure may not be generating much power. Ruedi was at 7,708.7 feet Wednesday. When Ruedi is full, the surface elevation is 7,766 feet above sea level.

When hydropower production decreases, Hunter said Aspen fills its all-renewable portfolio by buying more wind power.

“When hydro goes down, wind picks up the slack,” he said. “We are not in a terrible place right now. We are not Glen Canyon Dam.”

Hunter was referring to water levels in Lake Powell, which last week dipped to their lowest ever, hitting a target elevation of 3,525 feet, just 35 feet above the minimum level needed to generate hydropower at the dam.

“Hydropower across the board in the West is being affected by drought,” Hunter said. “This is crunch time, just watching what happens in the next month as we approach peak snow-water equivalent and see what the snowpack does.”

Aspen Journalism covers water and rivers in collaboration with The Aspen Times. For more, go to http://www.aspenjournalism.org.