News Release

Invasive smallmouth bass found in Colorado River below Glen Canyon Dam

Smallmouth bass

USFWS Photo/Eric Engbretson

News Release Date: July 11, 2022

Contact: [e-mail]

PAGE, Ariz. —On July 1, 2022, juvenile smallmouth bass were found in the Colorado River below the Glen Canyon Dam. Smallmouth bass are a predatory non-native fish that have adversely impacted native and federally protected fish in the upper basin of the Colorado River over the last 20 years. The National Park Service (NPS) is working closely with partners and stakeholders to coordinate rapid response actions to address this finding in accordance with previously approved management plans.  

Lower lake levels at Lake Powell and rising temperatures in the Colorado River have increased concerns that non-native, warm-water predators, including smallmouth bass, could pass through the dam and begin reproducing. If these warm-water predators establish populations below the dam, it is likely they would negatively impact native fish communities in Glen Canyon National Recreation Area and  in Grand Canyon National Park.  

The NPS encourages anglers to report any observations or catches of smallmouth bass below the dam. If caught, please remove the fish, put on ice and contact staff at Glen Canyon National Recreation Area or Grand Canyon National Park with a description of the location where found. Report findings to: Jeff Arnold, Glen Canyon National Recreation Area, e-mail us or Brian Healy, Grand Canyon National Park, e-mail us. 

For more information please visit:  

• Nonnative Fish - Glen Canyon National Recreation Area (U.S. National Park Service) (nps.gov)  
• Addressing Challenges to Native Fishes - Grand Canyon National Park (U.S. National Park Service) (nps.gov)  

-NPS-

NPS File

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NPS Flyer Alt text:

Title: Help Us Detect Invasive Smallmouth Bass

Image 1: Male smallmouth bass guarding a nest

Image 2: close up image of male smallmouth bass guarding a nest

Smallmouth bass are a dire threat to the Lees Ferry rainbow trout fishery and Grand Canyon’s native fishes, including humpback chub.

Image 3: illustration image of smallmouth bass with spiny fins and red eyes

Image 4: illustration image of young smallmouth bass with spiny fins and dark eyes
Image 5: smallmouth bass in water

As Lake Powell levels lower, river water temperatures are rising, providing ideal conditions for smallmouth bass. Temperatures of 61°F (16°C) and above are ideal for spawning of these nonnative predators. They guard nests in calm habitats like backwaters or tributary pools.

Watch for smallmouth bass in eddies, backwaters, and tributary mouths. Help us detect and remove these predators before it’s too late. Harvest bass—do not release them alive. If you see or catch bass, please email an NPS fish biologist below with location and date.

Jeff Arnold, Glen Canyon National Recreation Area,

Brian Healy, Grand Canyon National Park.