This section of the Colorado River at the boat launch near Corn Lake dipped to around 150 cfs in lake August. Known as the 15-mile reach, this stretch of river should have at least 810 cfs to meet the needs of endangered fish.
Streamflows on the Western Slope have plummeted over the last month, sending water managers scrambling to boost flows for endangered fish and ranking it among the driest years in recent history.
According to the Natural Resources Conservation Service, the Roaring Fork River basin ended the month of July at 28% of average streamflows. The Colorado River headwaters was at 42% of average; the Gunnison River basin was at 34% of average and rivers in the White/Yampa/Green River basin in the northwest corner of the state were running at 24% of average. Prior to this week's rains, the Crystal River near the Colorado Parks and Wildlife fish hatchery was running at 7.5 cfs, or 10% of average.
"We've been seeing pretty widespread well-below-normal flows across the entire upper Colorado River basin due to extremely dry conditions starting back in December," said Cody Moser, a senior hydrologist with the Colorado Basin River Forecast Center.
For most of August, the Crystal River near fish hatchery was running at less than 15 cfs. These extremely low conditions plus water temperatures above 71 degrees Fahrenheit, prompted CPW to implement on Aug. 15 a full-day voluntary fishing closure on the Crystal from mile marker 64 on Highway 133 to the confluence with the Roaring Fork. This section of the Crystal is downstream from big agricultural diversions and ditches owned and operated by the town of Carbondale.
The upper Roaring Fork River and its tributaries are also suffering the consequences of low flows. On Aug. 25 the Colorado Water Conservation Board placed a call for the minimum instream flow on a seven-mile section of the Roaring Fork through Aspen, between Difficult and Maroon creeks. The call was released the next day after rain boosted flows above the 32 cfs minimum amount.
The CWCB is the only entity in the state allowed to hold instream flow water rights, which are intended to preserve the natural environment to a reasonable degree. It's not uncommon for the CWCB to place calls for this stretch in late summer and it did so in other years, including 2012, 2018, 2020, 2021 and 2022.
Low flows have also affected recreation at the North Star Nature Preserve, a popular area for paddle boarders east of Aspen. On July 24, Pitkin County implemented a voluntary float closure -- asking people to launch at South Gate instead of Wildwood -- which occurs when the river falls below 60 cfs.
"At low water levels, users are at risk of touching bottom, which could damage the riparian habitat and would be considered trespassing," a Pitkin County official said in an email.
Before this week's rainfall, the Roaring Fork above Aspen hovered around 30 cfs.
Streamflows across the Western Slope are often at some of their lowest points of the year during the late summer and early fall when snowmelt has waned and irrigators are still drawing from streams. But this summer's lack of precipitation and low soil moisture were the main drivers of dry streams. Much of the Western Slope is in extreme or exceptional drought, according to the U.S. Drought Monitor.
"The biggest factor is the dry spring conditions and layered on top of them a much drier than normal summer," said Peter Goble, assistant state climatologist. "We will be watching those base flows but also soil moisture levels as we go into fall and early winter to see if those pick back up."
Dry soils that suck up snowmelt before it makes it to streams can mean a normal snowpack translates into below-normal runoff.
STRESSED OUT FISH
Another area hard hit by low flows is the 15-mile reach of the Colorado River between Palisade and the confluence with the Gunnison River. The chronically dry section is home to multiple endangered fish species and is downstream from some of the biggest agricultural diversions from the Colorado River in the state. Each year water managers work together to time voluntary releases from upstream reservoirs to boost late-season flows for the fish.
But even with many entities working with the Upper Colorado River Endangered Fish Recovery Program, a 2022 memo from the U.S. Fish and Wildlife Service found that during the irrigation season of dry years, flows did not meet the 810 cfs target 39% of the time.
This year, flows have not been above 810 cfs since July 9. And although flows in the 15-mile reach have been climbing since Aug. 23, -- up to about 650 cfs on Aug. 27 -- nearly all the water in the reach before this week's rain was attributable to upstream reservoir releases specifically intended for endangered fish. Without releases for the recovery program, flows in the 15-mile reach could have dipped as low as 30 to 50 cfs.
"From my standpoint it's amazing how a dry year just makes it really hard to get down even a third of that flow target," said Bart Miller, healthy rivers director with Western Resource Advocates. "It's a challenging time for water users, but a super challenging time for fish. For the fish it's a huge stressor."
This year there was about 29,175 acre-feet earmarked for endangered fish, according to a presentation by program staff. But by Sept. 1 nearly all this water was scheduled to be used up. The nonprofit Colorado Water Trust has stepped in to lease an additional 5,000 acre-feet out of Ruedi Reservoir. The water is owned by the town of Palisade, the Colorado River Water Conservation District and QB Energy. The releases of about 100 cfs are projected to begin Aug. 27 and continue through mid-October, said Danielle Snyder, a water resources specialist with the Colorado Water Trust.
"This particular stretch is very critical for the health of the ecosystem," Snyder said. "We saw a lot of benefit for both the community and the environment and we thought this would be a great opportunity given we have the capacity and funds to provide water to that region."
The CWCB will also lease an additional 2,350 acre-feet for fish flows.
Locally dwindling streamflows have big implications downstream. Projections released earlier this month from the U.S. Bureau of Reclamation show the nation's two largest reservoirs -- Lake Powell and Lake Mead -- continuing to drop. Lake Powell could drop below the level needed to make hydropower by late 2026. As proof of how dry the month of July was across the basin, inflow to Lake Powell was just 12% of normal.
One bright spot in an otherwise bleak forecast is that parts of the Western Slope are finally seeing some relief from the hot and dry summer with rain this week. But it probably won't be enough to make up for the months-long lack of precipitation.
"We have been dry for six-plus months so I don't imagine it will have a significant impact long term, but it's nice to finally see some precipitation in the forecast and observed over the last day or two," Moser said.
Aspen Journalism is a nonprofit, investigative news organization covering water, environment, social justice and more. Visit http://aspenjournalism.org