CPW to begin fishery renovation of Gypsum Ponds State Wildlife Area

Rachael Gonzales
Northwest Region Public Information Officer
970-773-8587 / [email protected]
Twitter: @CPW_NW

CPW to begin fishery renovation of Gypsum Ponds State Wildlife Area

GYPSUM, Colo. - Colorado Parks and Wildlife has begun efforts to drain the ponds at Gypsum Ponds State Wildlife Area to eradicate illegally introduced invasive fish and eliminate their threat to the adjacent Eagle River. CPW began lowering Gypsum Ponds in June for outlet renovations by curtailing water diversion and urging anglers to harvest fish from the ponds through an Emergency Fish Salvage issued June 18.  

“Gypsum Ponds has the potential to be a great fishery with both warm water and catchable trout fishing opportunities,” said Kendall Bakich, CPW Glenwood Springs Area Aquatic Biologist. “Recently, we discovered black bullhead catfish in the ponds. Bullhead catfish, smallmouth bass, and green sunfish currently dominate the pond fishery, and are voracious predators that eat other fish and limit the production of more desirable sportfish.”

Originally managed for catchable trout, over the years multiple warm-water fish species have invaded the ponds, likely through illegal introduction. CPW staff first documented the presence of restricted invasive fish species in Gypsum Ponds during routine monitoring in 2010. In 2012, fish screens were placed to mitigate their potential for escape from the ponds. Annual monitoring and mechanical removals have been unsuccessful in depleting the targeted fish species.

CPW reminds the public that it is unlawful to move live fish to other waters, including waters within close proximity. Penalties for doing so can result in fines of up to $5,000 plus eradication and removal costs.

To eradicate current fish species, pumps will be utilized to drain the remaining water in the ponds and complete the drawdown process which began in June 2024. In addition to removing the remaining water, CPW may consider the application of a fish toxicant (piscicide) called Rotenone, an EPA-registered piscicide. After pumping operations commence, CPW will determine which method or combination of methods will be necessary. 

CPW has been using rotenone, an organic compound derived from the root of a tropical legume (pea family), for over 80 years. This has been carried out by experienced and certified personnel to manage fisheries statewide. Indigenous peoples have also used this root to capture and harvest fish. The purpose of using rotenone is to achieve ecological balance, control and remove non-native fish, and reintroduce native fish to lakes and streams. Rotenone is chosen for its immediate effectiveness and quick degradation in the environment. When applied, it is toxic only to gilled organisms such as fish and macroinvertebrates and will not threaten other species that visit the ponds or linger in the carcasses of fish or the treated habitat they may access.

If deemed necessary, the chemical application process will occur in late September or early October. CPW will post placards around the ponds identifying application and restrictions during treatment. Since the ponds will be isolated and drained with no water flowing out of the ponds, the application will pose no threat to aquatic organisms in the adjacent river and wetlands or downriver water users. 

“Attempting full eradication now while the ponds must be lowered for the outlet renovations is not only our best opportunity for successful eradication, it is also our best chance to prevent the spread of highly invasive fish species to the adjacent river,” said Bakich.  

Once the ponds are lowered, CPW will begin construction to improve water control structures on the upper and lower ponds allowing for better control of water levels. 

During construction, the SWA and the road leading to the ponds will be closed to vehicles and the ponds will be closed to all visitors, but anglers will be able to walk the road and access the river on foot. People accessing the property on foot should be cognizant of the heavy equipment traffic on the road. The construction work is expected to start in late Sept. and last about two months.

The ponds will be filled again in April 2025, and will likely return to normal levels within a few weeks. In the spring, macroinvertebrates will repopulate the ponds as they are refilled from the Eagle River diversion. If applied, the rotenone is expected to naturally break down during the fall and winter of 2024, long before the ponds begin to fill. CPW will monitor rotenone levels to confirm the toxicant has dissipated. If rotenone levels remain elevated longer than anticipated, CPW will deactivate the remaining rotenone through the application of an oxidizer.

CPW will begin restocking the ponds following the return of normal water levels. Initially, catchable trout will be harvestable for anglers. Our longer-term plan is to develop a diverse warm-water fishery in both ponds with distinctly different fish assemblages. Some species being considered based on their desirability to anglers and lack of threat to the adjacent Eagle River include largemouth bass, bluegill, yellow perch, and black crappie.  

“Our desire is to rebuild a robust and diverse fishery that will be unique to the valley.  The two ponds will be managed to provide distinctly different fish assemblages that will offer fish targeted by a variety of anglers and encourage ecological balance to enhance fish growth for memorable fishing and quality harvest,” said Bakich. 

CPW will engage anglers and the local community in finalizing the pond management strategy this winter. In the upcoming months, look for announcements of public engagement opportunities.

For more information on fishery management in Colorado, visit the CPW website.