Suckers and suckers and chubs, oh my!

DRD plan addresses pollution, water releases to help preserve native fish

Keywords: Rivers, Fishing,
The setting sun reflects orange on the Dolores River below the McPhee dam as a fisherman wades out to fish. Enlargephoto

Sam Green/Cortez Journal

The setting sun reflects orange on the Dolores River below the McPhee dam as a fisherman wades out to fish.

Two suckers and a chub are a formidable gang of native fish that have been claiming the waters of the Lower Dolores River as their turf for millennia.

But survival of the bluehead sucker, flannelmouth sucker, and roundtail chub is uncertain because their tough neighborhood is plagued by drought and is located downstream of a major dam.

Their plight is a focus of a newly released study by the Dolores River Dialogue (DRD) that outlines a proactive approach to the fish’s continued existence.

The “Dolores River Nonpoint Source Pollution Watershed Plan” is the result of a five-year study by the DRD, a coalition of stakeholders dedicated to improving ecological conditions downstream of McPhee Dam and reservoir.

“It is a menu of ideas for the future of water quality on the lower Dolores,” said Marsha Porter Norton, coordinator for the study. “It is an educational document that focuses on water quality, native fish, and why they matter.”

The study identifies five reaches of the Dolores river where poor water quality may pose a threat to native fish, which are driving conservation efforts.

Temperature, sediment, uranium, salinity, and nutrients are generally at levels that comply with water quality standards established by the Colorado Water Quality control Commission.

However, “These parameters are thought to have potential to be stressors on native fish reproduction and survival in the Lower Dolores River,” the report states. “Therefore, the plan is intended to identify opportunities to mitigate such stressors through improved voluntary watershed management and protection efforts, even for parameters that do not exceed regulatory thresholds.”


The study focuses on nonpoint source pollution (NPS) on the approximate 108-mile stretch between McPhee Dam and the confluence with the San Miguel River.

Unlike pollution from industrial and sewage treatment plants, NPS comes from many diffuse sources and is transported by rainfall and snowmelt. Examples include agricultural runoff, chemicals from urban areas, acid drainage from abandoned mines, and bacteria from livestock and faulty septic systems.

Water quality on the lower Dolores is considered good in general, but there are some areas of concern.

“The main reason why water quality is so good on the lower Dolores is because there is so little development there,” said Jeff Kane, a co-author of the study.

In 2012, two segments of the river were listed as having “impaired” water under standards set by the Clean Water Act for aquatic life use standards.

According to the report, high levels of iron are present in the section from Little Gypsum Valley to the Colorado/Utah state line. And Roc Creek, a Dolores tributary downstream of the San Miguel confluence, contains levels of copper that exceed the standards.

Additional monitoring of pollution is recommended for five areas where there is reason to suspect water quality problems, including Lost Canyon Creek (E. coli), Little Gypsum Valley downstream to the Utah state line (E. coli), Disappointment Creek (Selenium, E. coli), West Paradox Creek (E. coli, iron) and Roc Creek (E. coli).

The study determines that the few areas of concern are not a major threat for conserving native fish populations on the Lower Dolores River. Instead it focuses information and solutions on the five threat areas of temperature, sediment, salinity, uranium and nutrients.


Temperature: Native fish below the dam are genetically cued to spawn in the warm-water temperatures of summer following the frigid spring snowmelt.

But the artificially low flows below McPhee dam in April and May cause the Lower Dolores to unnaturally heat up early, triggering the native fish to spawn prematurely.

In years when there is a whitewater release, managers time the spill for late May and June, but the fish have already spawned. Biologist suspect that the ill-timed chilling flush wipes out vulnerable young fry, contributing to the persistent population decline.

Ramping up the spill in March, April and May so it mimics a more natural hydrograph would keep the lower stretch colder longer, and effectively delay the spawn until after the boating season.

Sediment: When there are no releases from the dam, fine sediment builds up and is thought to hurt the native fish spawn. A release that mimics a natural spring flush washes sediment away, allowing eggs in gravel bars to receive adequate oxygen.

The study suggests a release of 400-800 cfs at least one day in the fall or spring to “mobilize fine sediments accumulated in pools and riffles with the goal of preparing cobbles for spawning.”

Uranium: The lower Dolores River flows through the “Uravan mineral belt,” one of the most productive uranium mining areas in the United States during the first half of the 20th century. Water quality impacts from uranium tailings have been cited as a cause of low populations of native fish in the Dolores River. Uranium in water appears to suppress some fishes’ physiological defenses against oxidative stress. Monitoring of reclaimed uranium mines at Slick Rock has been successful and the sites show no negative impacts to the Dolores River.

Recent increases in the price of uranium have prompted renewed interest in uranium mining. In July 2008, the federal Department of Energy approved a plan that allowed uranium leasing on 42 square miles in Colorado and Utah, expanding the area that could be leased and mined in the Dolores watershed. Thirty-one leases and 43 mines were approved under the plan. However, in 2012 the plan was halted, pending NEPA analysis of the impacts of this plan on federally listed endangered fish species.

The study concludes that there is not enough known about the effects of the uranium pollutants on the native fishery.


The Dolores pollution study takes a preventative approach to river management.

It states: “The advantage of preparing a nonpoint source watershed plan is it can identify pollutants of concern and voluntary protection actions before conditions degrade.”

A practical, efficient approach to conservation is another theme, said co-author Kane.

“Compiling what is known about water quality so organizations know where to focus their efforts and prioritize makes a difference,” he said. “For example there has long been suspicion of impacts from uranium mining, and with this study stakeholders can better identify where more information is needed.”

He notes that managers of McPhee reservoir have been more flexible in how they think about and deliver water downstream to aid native fish habitat and needs.

“They have been more open to facilitating a natural hydrograph below the dam to address things like water temperature and sediment movement that affect fish,” Kane said. “This study lays a foundation for entities to develop monitoring systems that will help reservoir managers see that their efforts are making a difference.”

The study is packed with historical information on the Dolores Project and local agriculture. It contains in-depth local stories about rafting, farming and the economies of the region.

“People will find the information interesting; the collaboration around this from different user groups and stakeholders was really rather incredible,” said study coordinator Porter-Norton.

The Dolores River Dialogue (DRD) group will meet on Tuesday, July 2 from 7 to 9 p.m. at the Dolores Water Conservancy District at 60 South Cactus in Cortez. The agenda will include an in-depth discussion of the watershed plan. The plan will also soon be available online.

Everyone is welcome, but those attending the meeting should RSVP by Friday, June 28, to Kathy Sherer ( to plan for seating, food and handouts.

The website for the DRD is