Colorado Parks and Wildlife

7/10/2023

Rito Hondo Reservoir to be treated ahead of Rio Grande cutthroat trout restoration

07/10/23

John Livingston
Southwest Region Public Information Officer
970-759-9590 / john.livingston@state.co.us
@CPW_SW

Rito Hondo Reservoir to be treated ahead of native Rio Grande cutthroat trout restoration

CPW aims to restore Rito Hondo Reservoir into a Rio Grande cutthroat broodstock lake in the coming years following a treatment project of the reservoir this summer.

CREEDE, Colo. – Presented with a unique opportunity, Colorado Parks and Wildlife will undergo a project to establish a population of native Rio Grande cutthroat trout in Rito Hondo Reservoir west of Creede.

Rito Hondo Reservoir has been lowered for dam repair work. With the water level lowered, CPW will do a rotenone treatment on the reservoir to remove non-native brook trout with the objective of stocking native Rio Grande cutthroats in the summer of 2024. CPW aquatic biologist Estevan Vigil said the lake is highly productive and will have the ability to grow large fish.

“The reservoir being drained for repairs gives us the opportunity to reclaim the lake itself and the stream above it without having to treat the whole lake,” Vigil said. “The coolest thing about this project is that it’s popping up out of nowhere and providing another lake that can grow really good trout.”

CPW aims to conduct the treatment project beginning the week of July 24. The lake will remain fishless through the winter. When dam repairs are complete, the lake will begin to refill following spring runoff in 2024. Then, it will be stocked with the native fish.

“We anticipate this being a great conservation success,” Vigil said. “We hope to establish this as a broodstock lake to get more Rio Grande cutthroat eggs for stocking out across the San Luis Valley.”

CPW is conducting this project in coordination with partners at the U.S. Forest Service and the San Luis Valley Chapter of Trout Unlimited. To provide for public safety during the construction process, the Divide Ranger District has closed the roads and area around the dam. The closure order can be found here.

To establish native cutthroat trout habitat in suitable streams, removal of non-native trout is essential. Non-native trout compete, prey on and/or readily hybridize with cutthroat trout. Successfully establishing a Rio Grande cutthroat trout population requires removing all the non-native trout before Rio Grande cutthroats can be stocked.

The removal of non-native fish is done with the use of the EPA-registered piscicide rotenone, an organic chemical that comes from a tropical legume (pea family) root that has been used by indigenous peoples to capture fish and has been used throughout the world for fish management projects. Rotenone only affects gill breathing animals and invertebrates when used properly. CPW, as well as other state fish and game agencies, have successfully used rotenone for more than 80 years to remove fish in controlled and targeted reaches of lakes and streams.

Once the Rio Grande cutthroat trout are re-established, anglers will have the unique opportunity to catch this native fish. Vigil said it could take three to five years for Rito Hondo to produce large, catchable fish that anglers are accustomed to reeling in on the lake.

The Rio Grande cutthroat is one of three native trout indigenous to Colorado. The Colorado River cutthroat is found on Colorado’s Western Slope, and the Greenback cutthroat is found on the Front Range. CPW is also working on a variety of projects to restore those populations.

For more information on Rio Grande cutthroat trout, go to https://cpw.state.co.us/learn/Pages/ResearchRioGrandeCutthroatTrout.aspx

CPW Aquatic Biologist Estevan Vigil shows the beautiful spawning colors of a male Rio Grande cutthroat trout.

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CPW is an enterprise agency, relying primarily on license sales, state parks fees and registration fees to support its operations, including: 43 state parks and more than 350 wildlife areas covering approximately 900,000 acres, management of fishing and hunting, wildlife watching, camping, motorized and non-motorized trails, boating and outdoor education. CPW's work contributes approximately $6 billion in total economic impact annually throughout Colorado.

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Rito Hondo Reservoir to be treated ahead of native Rio Grande cutthroat trout restoration