Colorado anglers asked to adjust practices as water temperatures rise

As warm weather persists and water temperatures rise, Colorado Parks and Wildlife (CPW) is asking anglers to help protect the state’s fish by following best practices for fishing in the heat.

Persistent warm temperatures this summer, coupled with below-average precipitation, have led to lower water levels and rising water temperatures in many of Colorado’s more than 6,000 miles of streams. As warm water holds less dissolved oxygen — making it difficult for fish to recover from the stress of being caught — this presents a threat to trout and other cold-water species, especially when exposed to additional pressure from angling. 

“This combination of high temperatures and low precipitation means there is less habitat and lower oxygen levels than is ideal,” said Matt Nicholl, assistant director for CPW’s Aquatic Branch. “This combination is a challenge for our fish species and makes them more vulnerable to stress then they otherwise would be.”

Water temperatures in excess of 70 degrees increase mortality rate for catch-and-release trout significantly. Late-afternoon readings on the Rio Grande, Arkansas and Colorado Rivers and some of their tributaries are regularly exceeding 70 degrees, with conditions expected to worsen.

CPW asks anglers to continue being good stewards of Colorado wildlife by adhering to voluntary fishing closures in the hopes of avoiding mandatory closures throughout the summer. 

CPW may enact mandatory fishing closures when any of the following criteria are met:

• Daily maximum water temperature exceeds 71 degrees.
• Streamflow drops to 50 percent or less of the daily average.
• Fish condition deteriorates, showing visible signs of fungus or stress.
• Daily minimum dissolved oxygen levels fall below 6 parts per million.

What you can do

• Know before you go: See a list of all fishing closures in place in Colorado.
• Limit fishing to the morning hours before water temperatures peak in the late afternoon.
• Minimize fish exhaustion by landing them quickly and keeping them in the water during handling.
• Practice proper handling and reduce fish stress: 
  • Avoid squeezing.
  • Keep fingers out of gills. 
  • Remove hooks gently.
  • Use heavier tippet and line to land fish quickly.
  • Wet your hands before handling any fish.
  • Keep fish submerged in the water while unhooking and releasing them.
  • Avoid removing fish from the water for photographs.
  • Avoid overcrowded areas and have an alternative fishing location planned.
• Keep fish that cannot maintain balance; exhausted fish are unlikely to survive if released. Area regulations allow for limited harvest and can sustain some angling mortality.

CPW recommends anglers fish early in the day to avoid peak afternoon temperatures. Anglers should use a handheld thermometer to test water conditions and move to cooler, higher-elevation waters once temperatures approach 71 degrees.

“We want to thank local guides and anglers who are respecting our waters and fishing responsibly. We also want to encourage them to be aware of the conditions when fishing and to make informed decisions that help protect Colorado’s wildlife,”  Nicholl said. “CPW and our partners will continue to provide updates on voluntary and mandatory closures as well as water conditions across the state.”

CPW’s Aquatics Branch attends monthly Colorado Water Conservation Board Water Conditions Monitoring Committee meetings to get updates on river flows and reservoir levels across the state, and continues to closely monitor water temperatures to determine if further action is needed to protect local fisheries. In the event of a closure, the public will be notified and signs will be posted at access points to inform anglers.

Exploring Colorado waters

Colorado offers unrivaled opportunities to fish for more than 35 species, including both warm- and cold-water fish, in some of the most scenic bodies of water. Licensed fishing is permitted on more than 6,000 miles of streams and over 1,300 lakes and reservoirs. Those looking for other fishing opportunities this summer can use the CPW Fishing Atlas to easily locate prime fishing areas. Whether you're interested in exploring alpine lakes with their cooler waters or seeking warmwater fishing opportunities, Colorado has something to offer for every fishing enthusiast. 
 
What resources does CPW have for anglers?

• CPW Fishing Atlas.
• 2026 Colorado Fishing Brochure (Pesca en Colorado​ En Español​​​​​​​).
• Colorado Quality Waters: Waters based on fish sampling records, creel surveys and professional biological assessments.
• CPW Event Calendar: Find upcoming state park events and fishing classes.
• CPW Fishing eNews: Get monthly fishing news, stocking reports and fishery surveys.

For more information, contact your local CPW Office.