Know before you go
Reading river flows: what CFS means for your day
Two numbers tell you a lot before you leave the house: how much water is moving, and how cold it is.
River flows are measured in CFS, cubic feet per second: how much water passes a gauge each second. The U.S. Geological Survey runs gauges on most Colorado rivers, and our river conditions page shows the current numbers for the waters we fish.
Compare a river to itself
A number only means something next to that river's normal. 50 CFS is a healthy winter flow on a small tailwater and a trickle on the Colorado. Watch a river over a few trips and you'll learn which flows you like to fish.
Watch the trend, not just the number
- Steady flows are usually the best fishing. Fish settle into their spots and feed on a predictable schedule.
- Rising and off-color water knocks food loose. It's a good time for streamers and bigger nymphs fished near the banks.
- A sudden jump below a dam means a release. The river can rise fast, so wade with care and keep an eye on the water at your feet.
- Spring runoff (roughly May through early July) brings high, cold, muddy water to freestone rivers. Tailwaters and lakes are often the better bet.
Water temperature
Trout are most active in roughly the 45 to 65 degree range. In the cold of winter they feed slowly and mostly mid-day. In summer heat, water over the high 60s stresses them. Fish early in the day, land fish quickly, and call it a day when the water warms up. Colorado Parks and Wildlife sometimes asks anglers to avoid certain rivers during hot afternoons, so check before you go.
One more thing
Gauge data is provisional and gauges sometimes go offline or freeze in winter. Use it to plan, then trust what you see at the river.
