Dangerously High Water Temperatures
2019 runoff is great but 2018 was extremely hot and dry. That made it a killer summer for our fish. Literally...
Finally by late August 2018 daytime highs decreased and we had both a bit of rain and some releases of water. That combination helped to lower our stream temperatures a bit, but the fundamental reality remains that high water temps put trout at serious risk. Warm water holds less oxygen and trout have trouble getting enough oxygen in water over 65 degrees. They can suffocate when water temps get into the 70's. Playing, catching and releasing a fish in warm water is often a death sentence for that fish.
You all know the satisfaction and importance of "catch and release" fishing, but local summer water temperatures resulting from our changing climate have been so high that fishing after about 1 PM on most of our rivers has become "catch and kill". Record high air temperatures and low water flow levels combined with no release of water from reservoirs into our rivers by diverters have resulted in dangerously high summer water temperatures in our streams.
As fishermen and women who must also be stewards or our environment.
Here is what we can do all summer long. Fish with a thermometer. If water temperatures are above 65 stop fishing or, at the very least, follow the suggestions to the right. Often, that means we shouldn't fish after 1 PM on most of our rivers and last summer the Department of Wildlife began posting notices to that effect.
Trout Unlimited is routinely in talks with water diverters and we hope to negotiate water releases whenever they are needed in the future. Our warming climate plays a role in stream temperatures, but in our area, the primary challenge is caused by water diversion. We're encouraging Denver and other diverters to implement watering restrictions and to begin releasing water into our rivers when it’s needed most. Denver Water is not obligated to make releases until they have all their permits, but releasing water at critical times would be good for our environment and would simply be a good public relations move for them.
Over half the water from our rivers in the Fraser Valley was diverted during one of the warmest and driest years on record. The result is a spike in water temperatures in our rivers. In this dangerous time for our rivers, TU is encouraging Denver to put manditory watering restrictions in place. During the summer of 2018, there were no restrictions on watering in Denver. We're also encouraging Denver to release water into our rivers when it's especially important to our environment. We encourage you to ask Denver Water and other diverters about this.