ST. GEORGE — With the end of the public comment period looming, Southern Utahns only have a few more days to share their opinions on how to reduce the threat of nonnative fish below Glen Canyon Dam.

A smallmouth bass swims underwater in this file photo, date and location not specified | Photo courtesy of Eric Engbretson/U.S. Fish and Wildlife Service, St. George News

On Feb. 9, the U.S. Bureau of Reclamation published the draft Supplemental Environmental Impact Statement, featuring various options for timing water releases to disrupt smallmouth bass spawning in the Colorado River below the dam.

This kicked off a 45-day comment period, which ends Monday, March 25, according to the agency’s website.

Due to an ongoing drought in the West that has lasted for over two decades, the Colorado River’s flows have been reduced by approximately 20%, and water levels in Lake Powell have dropped, St. George News reported.

The reservoir experienced record-breaking low water levels in 2022 and 2023. And while last year’s above-average snowmelt gave the reservoir a temporary boost, NASA’s Earth Observatory said, “long-term drought remains.”

In this file photo, bathtub rings show how low Lake Powell levels have declined, Page, Ariz., June 8, 2022 | Photo courtesy of Brittany Peterson/The Associated Press, St. George News

Lake Powell’s low water levels are at the crux of the problem, as previously reported by St. George News. Smallmouth bass are predatory, invasive fish that typically prefer the warmer waters at Lake Powell’s surface. As the reservoir’s elevation dropped, they were able to pass through Glen Canyon Dam’s water intakes into the river in 2022 and again in 2023.

Warmer water from Lake Powell’s surface increases the river’s temperature, “creating ideal spawning conditions” for nonnative species like smallmouth bass and other nonnative species, which threaten the federally protected humpback chub, the bureau states.

The number of smallmouth bass more than doubled since 2022, according to the Center for Biological Diversity. Most of the humpback chub’s remaining population is located at the junction of the Colorado and Little Colorado rivers in the Grand Canyon after smallmouth bass “eliminated an entire population” in the upper basin.

In this file photo, a person holds a federally protected humpback chub near the Colorado River, date and location not specified | Photo courtesy of the U.S. Fish and Wildlife Service, St. George News

According to the impact statement, smallmouth bass could also negatively impact other native fish species downstream of the dam, including bluefin suckers, flannelmouth suckers, speckled dace and endangered razorback suckers.

The agency’s Upper Colorado Basin Regional Director Wayne Pullan said the establishment of invasive fish would threaten the progress made via previous recovery efforts and the agency will need to have access to the proposed range of options before this year’s spawning season.

“Because eradicating an established invasive species is expensive and extraordinarily difficult, it is important that we have these tools,” he said.

In this file photo, razorback suckers swim in a take in Lakewood, Colo., Oct. 2, 2018 | Photo courtesy of Dan Elliott/The Associated Press, St. George News

The impact statement lists six alternatives for addressing the issue, one of which considers what would happen should the bureau take no action as required by the National Environmental Policy Act.

According to the statement, taking no action would allow the water temperature to continue rising, resulting in the spread of smallmouth bass and other nonnative species in the Colorado River.

The next four alternatives use various flow options to maintain a daily average water temperature of 55-60 degrees Fahrenheit, including cold shocks and flow spikes. Flow spikes would consist of up to three 36-hour water releases of up to 45,000 cubic feet per second, according to the agency’s website.

The fifth, nonbypass alternative would use weekly short-duration, low-flow releases to dewater nonnative fish nests, followed by short, high-flow releases to flush out remaining nests, the bureau states. All releases listed would be timed on an experimental, hourly, daily or monthly basis, and not annually. Annual releases are determined by 2007’s Colorado River operating guidelines.

This file photo shows the Colorado River as it runs downstream from Glen Canyon Dam, Page, Ariz., June 10, 2022 | Photo by David Dudley, St. George News

“The five alternatives each have the potential to disrupt smallmouth bass spawning by either desiccating or inundating nesting areas, creating unsuitable water temperatures, or both,” according to the impact statement. “Potentially, the most effective alternatives for disrupting smallmouth bass spawning are the Cool Mix with Flow Spike and the Cold Shock with Flow Spike Alternatives, as these alternatives theoretically would disrupt both the physical habitat of smallmouth bass nesting as well as the suitable and necessary temperature regimes.”

The impact statement supplements 2016’s Glen Canyon Dam Long-Term Experimental and Management Plan Final Environmental Impact Statement and Record of Decision, according to a news release issued by the bureau. Last year, the bureau released a draft environmental assessment containing flow options and asked for the public’s input. They received nearly 7,000 comments.

Comments included various control methods not listed in the environmental impact statement, including the installation of barriers, like screens or nets, to prevent nonnative fish from passing through the dam.

The National Park Service stated that while the bureau is pursuing this option “separately on a longer timeline,” there are available options using nets that could be used sooner.

This file photo shows the Colorado River from Glen Canyon Dam, Page, Ariz., June 10, 2022 | Photo by David Dudley, St. George News

The park service adds that they urge consideration of those options to be used in combination with the flow options.

“If they (nets/barriers) could be installed and used sooner, it would make a difference while we are in the early stages of the invasion curve.”

The agency states that the final environmental impact state and Record of Decision are expected by early this summer.

Southern Utahns interested in submitting comments must do so by March 25 via email.

Comments can also be mailed to the Bureau of Reclamation, Attn: LTEMP SEIS Project Manager, 125 S. State Street, Suite 800, Salt Lake City, Utah 84138.

The project’s page featuring additional information can be found at this link. To read the full draft of the environmental impact statement click here.

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