CPW proposes ambient temperature standards below Pueblo Dam

Colorado Parks and Wildlife is proposing new water-temperature standards for the Arkansas River below Pueblo Dam. KKTV reported that water-quality staff laid out the change Thursday, Sept. 24, 2026, at a public meeting at Lake Pueblo State Park. The agency says the current standards do not match the temperatures that occur there for part of the year.

The proposal covers July through December. CPW plans to keep the existing standards from January through June. Mindy May, the agency’s water quality program coordinator, said the standards should reflect conditions already in the river, stay protective of the cold-water fishery, and stay achievable so the hatchery can keep operating. For the second half of the year the agency plans an ambient-based standard, set from historical temperatures in the river. May said the analysis found the river cannot consistently meet the current cold-water standards in those months. CPW said it used about 10 years of data from temperature loggers and a long-term U.S. Geological Survey monitoring site below the dam.

Releases from deep in Pueblo Reservoir run colder than surface water, and that cold water is what holds rainbow and brown trout in a tailwater anglers fish all year. CPW says the stretch was a warm-water fishery before the dam. The river is not consistently cold enough for those trout to reproduce on their own, so the populations are maintained by stocking. The Pueblo State Fish Hatchery raises fish for the river and the reservoir. Ashley Rust, a CPW water-quality monitoring and assessment specialist, called it one of the agency’s largest and most productive hatcheries. Rust said the tailwater gives people a year-round reason to be on the water.

The hatchery adds a small amount of heat to the river. CPW’s model removes that thermal contribution when it builds the proposed standard. Separately, Rust said the agency is working with an engineering firm on ways to cut the hatchery’s effect, including shading, how water moves, and the width of structures. The stated goal is to keep the fishery that is already there and to write temperature standards that match the river as it runs.

Photo: KKTV — Pueblo Dam and the Arkansas River below it, attached to the Sept. 25, 2026 story.

This is a The Gillnet news desk summary, not a reprint.

Source: KKTV — CPW proposes new water temperature standards below Pueblo Dam (Damien Bartonek, published Sept. 24, 2026).