Colorado Parks and Wildlife officials will soon use piscicide rotenone to eradicate non-native brook trout from the Creede-area Rito Hondo Reservoir ahead of a project meant to establish a population of native Rio Grande cutthroat trout in the lake.

The treatment chemical, which is described by officials as a commonly-used organic, EPA-registered chemical that comes from a tropical legume root, only impacts gill-breathing animals and invertebrates if used properly.

The chemical is set to be applied starting the week of July 24, with the lake remaining fish-free through the winter.

After dam repairs are complete and the lake is refilled with spring run-off in 2024, it will be stocked with native fish. These native fish are expected to be catchable by anglers within about three to five years.

“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,” said CPW aquatic biologist Estevan Vigil. “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.”

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

According to officials, the removal of non-native fish is necessary to prevent these fish from competing with, preying on, and hybridizing with native fish to be introduced.

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