Tinkering with a pollutant, Colorado ranch seeks to improve fish habitat | AspenTimes.com
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Tinkering with a pollutant, Colorado ranch seeks to improve fish habitat

Proposal on the Blue River would grow food for undernourished fish using phosphorus, which can cause toxic algae blooms

A fly fisherman on the Blue River in Silverthorne on Nov. 28, 2020, which is designateda "gold medal" status based on the size and abundance of trout. A downstream ranch is proposing adding phosphorus to the river in an effort to improve fish habitat.
John Herrick/Aspen Journalism

A private ranch is seeking Colorado environmental regulators’ permission to inject the Blue River with phosphorus — a chemical regulated as a pollutant — as part of an experiment that could help improve trout habitat at a popular high-country fishing destination.

Kremmling-based Blue Valley Ranch, owned by the billionaire philanthropist Paul Tudor Jones II, proposes beginning the project as soon as next summer on an 8-mile stretch of the river running through its 25,000-acre ranch, which is located on both sides of the river between Green Mountain Reservoir and Colorado River.

The ranch has not yet applied for a state discharge permit, which it will need before beginning the project. In September, the Colorado Basin Roundtable, a 35-member group of water planners, voted to provide Blue Valley Ranch, which did not request a financial contribution, with a letter of support.



The ranch sits alongside the lower section of the river. Areas on this stretch that have public access are home to relatively large and abundant trout, earning a “gold medal” status from the state. The experiment may help explain why trout farther upstream above the Green Mountain Reservoir appear undernourished. The ranch expects that adding phosphorus to the river will grow more algae, a building block in the aquatic food-chain supporting fish.

If the project helps the fish, water managers could use a similar one to restore the gold-medal status of a section of the Blue River upstream from the ranch’s property that the state delisted in 2016. The designation is based on the size and abundance of fish in rivers with public access. The rare delisting on the river section, north of Silverthorne, was a blow to residents who saw the designation as a way to attract outdoor tourism to the region.



Scientists warn that adding too much phosphorus could create problems downstream. Excess phosphorus creates cyanobacteria, an algae that can be toxic to humans. Last summer, such algae blooms prompted the state to issue warnings and closures to lakes across the state, from Steamboat Lake, north of Steamboat Springs, to Denver’s Cherry Creek Reservoir.

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This is one reason why the Colorado Department of Public Health and Environment is working on new rules to limit phosphorus pollution based on the chemical’s ecological impacts. The state may soon require owners of large facilities, such as wastewater-treatment plants, to make costly upgrades to comply with new limits.

That same agency will have to decide whether to grant the ranch a discharge permit, weighing the possibility of improving trout habitat with the environmental risks. MaryAnn Nason, a spokeswoman for the state’s Water Quality Control Division, said in a statement that the state would evaluate whether the additional phosphorus protects aquatic life, drinking water and recreation, and complies with the state’s regulations on phosphorus.

The theory behind the project is that the river has too little phosphorus, a circumstance that may be preventing the growth of periphyton, an algae eaten by aquatic insects that state biologists say are “sparse” in the river. One of the reasons the river lacks nutrients is that the 231-foot dam in Silverthorne is causing it to back up. The dam was built in 1963 to create the Dillon Reservoir, which Denver Water uses to ship drinking water under the Continental Divide to residents on the Front Range. The dam traps nutrients such as phosphorus and prevents downstream flooding, a natural process that can pull phosphorus back into the river. In the 1980s, the state imposed strict limits on phosphorus pollution from wastewater-treatment plant operators in the basin, which has kept phosphorus concentrations to about 10 parts per billion in the reservoir to prevent algae blooms. That means the cold water flowing out of the bottom of the dam also is relatively low in phosphorus.

“This is a success story,” said William Lewis, a professor at the University of Colorado Boulder and director of its Center for Limnology and who has studied the reservoir’s chemistry for decades.

Whether the successes of curbing pollution are hurting fish habitat downstream is hard to say for sure, Lewis said. But supporters of the Blue Valley Ranch proposal say the experiment could test this one factor among the many affecting the river.

“We have to better understand those factors. And measure them. And then rate them,” said Richard Van Gytenbeek, the Colorado River Basin outreach coordinator for Trout Unlimited, a nonprofit that advocates for fish habitat and supports the ranch’s proposed experiment.

Map of the Blue River drainage made using U.S. Geological Survey data on May 20,2018. A ranch on the Blue River between Green Mountain Reservoir and the confluence withthe Colorado River is proposing adding phosphorus to the water to improve fish habitat.
Map by Shannon1, courtesy Wikimedia Commons.

According to a presentation to the Colorado Basin Roundtable by Blue Valley Ranch, the company proposes placing jugs of liquid fertilizer at six sites along the river bordering its property, injecting it with as much as nearly 2,000 gallons per year. In an emailed statement from the company, it said it plans to increase the phosphorus concentrations in the river by 3 parts per billion. It would then sample the growth of periphyton, aquatic insects and the fish population. The company cites a project on Idaho’s Kootenai River in which researchers increased phosphorus levels of as much as about 12.5 parts per billion. Bob Steed, the surface water manager for the Idaho Department of Environmental Quality, said the Kootenai River project has increased the size and number of fish without causing toxic algae blooms or other problems with water quality.

But scientists still have reservations. Lisa Kunza, a professor of chemistry biology and health sciences at the South Dakota School of Mines and Technology who has studied the ecological impacts of the Kootenai River project, said she wondered whether Blue Valley Ranch plans to spend enough time studying baseline conditions before the experiment. And she wondered what’s motivating the company to do the project.

According to the company’s website, the ranch seeks “to be a leader in conservation.” Its owner, Jones, is an investor whose philanthropy has earned him recognition as a “conservationist.” Jones spent $805,000 on Highway 9 wildlife crossings north of Silverthorne as well as other projects across the county, including setting up a foundation aimed at protecting the Florida Mangroves. The property is known for its intensive management, such as using a diesel-powered backhoe to make the river narrower and deeper, and locals call the stretch of river flowing through the ranch “Jurassic Park.”

Brien Rose, a biologist with Blue Valley Ranch who has worked as a researcher for the U.S. Geological Survey, has been giving presentations on the project and speaking with the Department of Public Health and Environment. Rose did not respond to multiple requests for an interview.

Before the ranch stepped up with the idea, the concept of its experiment was already being discussed among the region’s water managers, some of whom are monitoring conditions upstream and perhaps laying the groundwork for a similar project. The Blue River Watershed Group, which helps manage the river, is backing the project. Supporters see it as a way to help restore the river to a more natural state before the dam trapped its nutrients.

“Studies of the lower Blue River have shown that it is deficient in some nutrients because of the two upstream impoundments on the river. A major goal of this research is to add to the base of knowledge that will ultimately benefit other impounded rivers in the Western United States,” said Brett Davidson, a manager with Blue Valley Ranch, in an emailed statement.

But what the river looked like before the dam is unclear, researchers say. Aside from the Dillon and Green Mountain reservoirs, the Blue River has been impacted by hardrock mining and the growing mountain towns of Silverthorn, Frisco and Breckenridge. For decades, the state has been stocking the river with brown and rainbow trout, game fish that white settlers introduced to Colorado. One of the reasons the middle section of the Blue River lost its gold-medal status was because the state scaled back stocking.

Sarah Marshall, an ecohydrologist with the Colorado Natural Heritage Program at Colorado State University, said she sees the value in Blue Valley Ranch’s experiment. She, too, wants to better understand the effects of phosphorus on a river’s ecology.

But Marshall said “further tinkering” with the river to restore it could have its risks. She added: “The proposed study sounds like a Band-Aid, rather than fixing the underlying causes of degraded stream habitat.”

Aspen Journalism is a local, nonprofit, investigative news organization partnering with The Aspen Times and other Swift Communications newspapers on coverage of water and rivers. For more, go to aspenjournalism.org


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