Keep Fish Cool

The Colorado Water Quality Control Commission (WQCC) is considering a state policy change that would increase the "standard" temperature for trout streams throughout the state. Proposed changes brought forth by the Water Quality Control Division (WQCD) would put many trout fisheries at risk including spawning periods. In order for trout to function properly, they need the water temperature to be between the ranges of 40-65 degrees. Some species- primarily the ones found in higher elevations like the cutthroat trout- are more sensitive to temperature changes and have a chronic limit of 60 degrees. When the water temperature falls within the trouts preferred range, the trout can no longer feed, grow or move properly.

Greenback at home in bear Creek

As the water becomes warmer, there becomes less dissolved oxygen available. Conversely, when the water cools, more oxygen is available and the fish can feed and move comfortably. Trout species require 4-5 times more dissolved oxygen when the water temperature is out of their preferred range than when the water is close to 40 degrees.

The changes proposed by the WQCD will increase the "standard" temperature in trout streams, causing their stress levels to increase and ultimately cause issues in their feeding, growing and movement.

These potential changes would allow higher elevation streams to reach 63 degrees- 3 degrees over the chronic limit for sensitive coldwater species. For middle elevation streams (the most common streams), the limit will be raised to 65 degrees, just about the chronic limit for most trout species in Colorado.

The potentially higher temperature standards would be allowed during the months of April to November- during the months of Rainbow and Brown spawning seasons when the fish are more sensitive and susceptible to changes in their environment. For more information regarding these changes, check out the report: Fish in Hot Water? by Mindi May and Ashley Rust.

photo 1Changes being proposed are potential, but the fish need our help. Trout Unlimited is conducting a Citizen Science for anglers throughout the state to record stream temperature, species, presence of redds (if possible) and photos to present to the WQCD. To conduct the Citizen Science form, visit the Google Doc created by Ashley Rust or submit findings to

The hearing will be on June 13 at 9:30 at the Department of Public Health. Along with our Citizen Science data, we want Trout Unlimited members, supporters and anglers to be there showing their support for our trout and the cold water they call home.