The dream of a new quality warm-water fishery for anglers on Colorado’s western slope is starting to see fruition after years of planning.
Colorado Parks and Wildlife Aquatic Biologists Eric Gardunio and Ben Felt have been busy over the past week transferring fish to Sweitzer Lake State Park from other bodies of water. Some of the transfers included largemouth bass from Confluence Lake in Delta and James M. Robb Colorado River State Park in Grand Junction, as well as bluegill from Hallenbeck Reservoir in Grand Junction. More than 330 largemouth bass between 6 and 18 inches long as well as 1,300 sunfish were moved into Sweitzer Lake. These fish will be supplemented later this summer by fish from CPW hatcheries.
“The goal in transferring from a few places was to get fish in different size ranges so we have multiple age classes building up the population,” Gardunio said. “We also tried to focus on moving fish in situations where it would benefit the ecology of the waters they were being moved from.”
The work took years of planning that included getting multiple organizations to sign off on a new lake management plan. Colorado Parks and Wildlife, along with other state and federal agencies, belongs to the Colorado River Endangered Fish Recovery Program that aims to recover endangered fish in the Colorado River basin. Historically, Sweitzer Lake contained green sunfish, black bullhead and common carp. Adding largemouth bass and bluegill was identified as a way to create a more desirable warm-water fishery that is compatible with native fish in the rivers.
The recovery program creates some limitations as to what species Colorado Parks and Wildlife can actively manage for in western Colorado.
“We can manage for largemouth bass and bluegill, but we need a lake management plan approved by other signatory agencies within the recovery program before we can go ahead and stock the lake,” said Gardunio. “So we’ve had to do a fair bit of background work on the plan as well as fundraising to install a fish screen below the lake that ensures no fish will escape and get into other surrounding waterways.”
Sweitzer Lake is a productive lake that has the potential to grow large fish. To further enhance the fishery, CPW has placed dozens of artificial habitat structures in the lake to help give the new fish a place to shelter as well as for anglers to focus their efforts.
CPW staff places artificial habitat structures into Sweitzer Lake. 
CPW measures a largemouth bass prior to release into the lake.
Fishing at Sweitzer is catch-and-release only, and these regulations should encourage the development of a quality sport fishery for healthy largemouth bass.
“The primary goal of this effort is to manage the fishery for big bass, which is something we hear local anglers requesting,” Gardunio said. “The recent stocking has created a new fishery in Sweitzer Lake that should continue to improve over the next several years.”
Related Resources
- Sweitzer Lake State Park
- 2021 Colorado Fishing brochure.
- Upper Colorado River Endangered Fish Recovery Program.
Travis Duncan is a public information officer for Colorado Parks and Wildlife in Denver. Travis has lived in Colorado nearly 20 years and loves the outdoors. If you have a question, please email him at travis.duncan@state.co.us.
