Colorado River endangered fish recovery sees some success, but enough water for a 15-mile reach remains a challenge
In May, students from Palisade High School gathered on the bank of the Colorado River to kiss goodbye to 250 juvenile, endangered razorback suckers and release them into the muddy, fast-moving spring runoff, marking the 50th anniversary of the federal Endangered Species Act.
For the past three years, Palisade High School student scientists have been raising the fish in a hatchery, feeding and weighing them, testing the water, cleaning their tanks and inserting a transponder tag so that biologists can track their movement once released each season as part of the Upper Colorado River Endangered Fish Recovery Program.
Razorback suckers, which can live to more than 40 years old and grow to 3 feet, are one of four prehistoric fish species that live only in the Colorado River basin and whose numbers declined with the acceleration of water development projects such as dams and diversions. In 1991, the species was listed as endangered under the Endangered Species Act, and it has become something of a success story for the recovery program. The populations have recovered enough in the Colorado River that the program is pulling back on stocking, and the U.S. Fish & Wildlife Service has proposed downlisting the species to threatened, a lesser category.
“In the last couple of years, we’ve gotten confirmation that at least two of the fish showed up on a spawning bar, completing the life cycle,” said Julie Stahli, director of the recovery program. “It’s a great sign.”
Because of rebounding populations, one of the razorback sucker’s fellow endangered species, the humpback chub, was downlisted to threatened in 2021. The other two endangered fish — the Colorado pikeminnow and bonytail — are not recovering as well as the razorback sucker and humpback chub.
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But, despite the successes and the coordinated efforts of federal and state agencies, upstream water users and environmental organizations, meeting minimum flow requirements in a chronically dry section of fish habitat remains a challenge, and stressors such as climate change, drought and nonnative predators are creating new hurdles for helping the fish recover.
Although the fish are arguably the earliest water users on the river, under Colorado’s system of water law, water for the environment typically has some of the most junior rights. Those who use water by taking it out of the river — farmers, cities, industry — usually have senior rights, giving them first use of the water and not always leaving enough for the fish. To remedy this, one of the main goals of the recovery program and its partners is to get more water into a chronically dry section of river in the Grand Valley where the fish live, known as the 15-mile reach.
The recovery program works to reestablish healthy populations of four species of fish that are listed under the Endangered Species Act by adding water to the river, restoring habitat, growing hatchery fish and controlling nonnative predator fish. It was created in 1988 to protect the fish while still allowing water development, two seemingly opposed goals.
“Shutting down water development in the West to save an endangered species was a no-go for everyone,” Stahli said. “They came up with what was then a very strange plan to use the water and recover the endangered fish at the same time. There are pathways for both.”
The 15 miles of the Colorado River between large Grand Valley agricultural diversions and where the Gunnison River adds its flow to the Colorado is critical habitat. It also tends to not have enough water to support healthy populations, especially during irrigation season in dry years. Water diversions to the Grand Valley to grow crops, including famous Palisade peaches, can combined take up to 1,950 cubic feet per second from the river — collectively, the biggest agricultural diversion from the Colorado River on the Western Slope.
A 2022 review of what is known as a Programmatic Biological Opinion, originally issued by the U.S. Fish & Wildlife Service in 1999, found that during the irrigation season of dry years, flows did not meet the minimum monthly recommendation of 810 cfs 39% of the time. Peak spring flows of more than 12,900 cfs, which are needed for healthy habitat and fish spawning, are also not met 31% of the time in dry years, despite a voluntary program where upstream reservoir operators can send extra water down to the 15-mile reach at the same time to boost the natural peak.
The inability to hit target flow recommendations has led the recovery program to begin the process of reevaluating whether the monthly 810 cfs benchmark was a realistic goal to begin with.
“The recovery program has determined that the service’s spring and summer base flow recommendations in dry years are unrealistic and appear to have been unrealistic through the entire period of record,” reads the review memo. “The recovery program should work closely with the service to determine if there is utility in revising the 15-mile reach flow recommendations to more closely align with what we know about Colorado River hydrology and which studies would be needed to support such revisions.”
This reassessment, which is scheduled to be completed by 2028, will look broadly at flow recommendations and the best ways to set them, according to Stahli. For example, a daily minimum flow recommendation may make more sense than a monthly average.
“It’s really an examination of how we are doing within the river basin and whether the 15-mile reach is still serving the ecological function we think it is,” she said.
One of the main actions of the recovery program has been working to add water to this reach. It has been the focus of the program’s environmental conservation partners such as The Nature Conservancy and Western Resource Advocates.
“Our approach is we have always very heavily emphasized the flow piece of it,” said Bart Miller, healthy rivers director at Western Resource Advocates. “In the last 23 years, there has been a lot of dry years. … It’s clear that in the system as a whole, there’s been less water.”
To combat these declining flows from drought and climate change, several entities offer up water they store in upstream reservoirs and release it for the benefit of the fish. For example, for the past few years, the Colorado Water Conservation Board has leased water owned by the Colorado River Water Conservation District, Garfield County and Ute Water Conservancy District in Ruedi Reservoir and sent it downstream to boost flows for the fish during dry periods.
Historically, 43% of the Upper Colorado and San Juan recovery programs’ funding, which was $8 million and $3.46 million, respectively, in 2022, has been spent on flow management and protection, according to the program’s 2023 report to Congress. Since 1998, dedicated pools in reservoirs for the fish and other sources have provided more than 1.7 million acre-feet to supplement flows in the 15-mile reach.
The recovery program helps fish in other ways, too, such as funding fish passages that help them move past dams; hatchery breeding and stocking; screens that prevent them from swimming into irrigation canals; and habitat restoration.
Nonnative predators that eat endangered fish and compete for habitat have increased since the fish were listed and are now the biggest threat to the recovery of the species, according to the PBO review memo. Smallmouth bass, northern pike and walleye are the biggest problems.
“I believe if we didn’t have nonnative fish, these (endangered) fish would be fine,” Stahli said.
Historically, the program has spent 6% of its funding on the management of nonnative species. But in fiscal years 2023-24, the program expects to spend 20% of its funding on getting rid of nonnative fish. Stahli said the recovery program catches 2 million to 3 million nonnatives a year.
“What keeps me up at night is nonnative fish,” Miller said. “They have the numbers throughout the basin and have really exploded over the last decade.”
One of the advantages of such a highly engineered and manipulated river system is that it creates opportunities for water users to coordinate their operations to the advantage of the endangered fish.
The first example of this is the Historic Users Pool, a 66,000-acre-foot pool of water in Green Mountain Reservoir, which is on the Blue River in Summit County. This water is earmarked for beneficiaries on the Western Slope, including the Grand Valley irrigators. But in some years, not all the water is needed and any surplus can be made available for endangered fish.
The details of the timing and volume of water to be released are hashed out on conference calls that can include more than 40 participants.
“In most years, the HUP surplus becomes the largest single source of flow augmentation for the 15-mile reach,” said Victor Lee, an engineer with the U.S. Bureau of Reclamation who coordinates the Historic Users Pool conference calls.
The second example is Coordinated Reservoir Operations, where upstream reservoir operators can voluntarily send a pulse of water that arrives at the 15-mile reach at the same time and enhances the peak flow of the year. Retiming excess flows in this way creates a flushing flow that clears out excess sediment built up on fish-spawning grounds over the previous year. Coordinated Reservoir Operations is managed by the Colorado Water Conservation Board.
“Each reservoir operator decides for themselves whether or not they will participate in CROS for that year,” said Michelle Garrison, a water resources specialist with Colorado Water Conservation Board. “The fundamental idea behind CROS is to retime what you were going to bypass anyway. If the reservoir operators don’t think they have excess inflow, they will not participate.”
Coordinated Reservoir Operations is more likely to occur in wetter-than-average years, but not extremely wet years, Garrison said. In 11 of the past 30 years, peak flows were supplemented with Coordinated Reservoir Operations releases. Coordinated Reservoir Operations did not happen this year because the prolonged high runoff from a big snowpack was enough of a benefit.
Despite its ongoing challenges, the recovery program proves that entities with different missions can come together for the good of four species of vulnerable wildlife. The fish, although they are the charismatic megafauna of the Colorado River ecosystem and are important in their own right, are also a proxy for river health. If humans can successfully aid in their recovery, it says something about our values, Miller said.
“Do we care that the rivers still flow in the month of August? And if we do, then these fish are the canary-in-the-coal-mine example,” Miller said. “They are the first species that are feeling the brunt of climate change and river management and diversions and everything humans have imposed on the river in the last century and a half. It’s a tribute to us that we can get together on a big geographic scale and put our energy behind trying to keep all the pieces of our larger Colorado River community in place.”
Aspen Journalism is a nonprofit, investigative news organization covering water, the environment, social justice and more. Visit http://aspenjournalism.org.