Fly Fishing Rivers During Runoff

Photo by Wayne Lewis/CPW.
Photo by Wayne Lewis/CPW.

As high-elevation snow melts and Colorado’s rivers swell with runoff, many anglers either hang up the fly gear or turn to stillwater alternatives. While there are certainly situations when this is the only sane alternative, I’ve also found that there are many overlooked opportunities for good fishing cached among the currents of spring.

When you consider the statistical portrayal of freestone rivers in the Rocky Mountains, the “average year” hydrograph looks very much like the traditional sweeping bell curve. In actuality, there are no “average” years, the average being a mathematical construct that is helpful in understanding trends in hydrology but is of little utility to fishing.

Every year is different and none of them follow a smooth progression of rising and declining flows through the runoff period. Rather, during (or following, depending on distance from the snowfields) periods of warm day and night temperatures and days of sustained direct solar radiation on the snow, tributaries and rivers will rise quickly, scouring debris and dust from their banks, increasing the current velocity while diminishing both the temperature of the water and its clarity.

Conversely, during cooler periods or times with significant cloud cover, the high-elevation melt will slow, allowing the flows to stabilize and clear, with water temperatures often rising. The appearance of these fluctuations on the graph of any given year’s flows looks more like a staircase than a bell curve, with the risers corresponding to periods of increasing flow and the treads depicting those times of stability.

If you want to get onto the river during runoff, you will do well to watch the seven-day forecast. Cooling trends and colder overnight lows will signal a river that will soon be clearing. A familiarity with the lag time in flows from snowfield to fishing point on the river is helpful and these can be calculated by correlating the weather with the flow graphs available on the Colorado Division of Water Resources website.

Using the Arkansas River as an example, a cool spell moving into the upper valley on a Monday will typically be reflected in the flows through Salida on Wednesday. Using the graphs available, you can also plot the daily “bubble and divot” for a given location on the river, timing your fishing to correspond with the flows produced by the period of lowest melt (midnight to early morning) from two days before.

After determining optimal days and times to fish, you should then tailor your approach to the conditions. During periods of very high flow, there will be strong current right along the river’s edge, often flowing directly through the shoreline willows. At these times, you need to take a step back and consider the river from a topographical standpoint. What is the “meta-structure” that will yield areas of slower current? Inside bends and pronounced rock promontories will generate areas of slower water and fish will congregate in such places to avoid the faster current. Many eddies may be churning from the friction of the current but look for those that are more stable. And then keep in mind that the deeper you fish in such locations, the milder the turbulence where your fly is actually drifted.

A two-fly rig with large stonefly patterns, girdle bugs and beadhead nymphs is effective in runoff conditions.  It's important to use splitshot to get flies deep.
A two-fly rig with large stonefly patterns, girdle bugs and beadhead nymphs is effective in runoff conditions. It’s important to use splitshot to get flies deep.

In this type of water, a two nymph rig with sufficient weight to cut through the turbulence quickly is essential. Dark patterns (stonefly nymphs, streamers, and large attractors like prince nymphs) all work well in these conditions. A favorite of mine is to fish a large stonefly like a girdle bug or Pat’s rubberlegs and then trail a size 10-12 copper john, prince or pheasant tail behind it. Fish a long, strong leader (9-12 feet) and no smaller than 3X. Add splitshot until you are certain that the flies are quickly getting down to the deepest laminar of flow, right along the structure of the bottom. Use a highly visible and buoyant strike indicator – it needs to be able to float through the conflicting currents and the fish can’t see it anyway. Depth is really key in this style of fishing. If it isn’t in that bottom 6-12 inches of the water column, the fish will not see it. I have fished this way effectively in as little as 8 inches of visibility.

A few thoughts on equipment: I prefer a floating line to a sinking or sink-tip line, as it is easier to mend and maintain a natural drift. Longer rods will help with the mending and also with the pick-up on such a long drop below the indicator. Don’t bother with waders—they will just make you want to get into the river, which is a dangerous proposition this time of year. Wear boots or running shoes with a good, grippy sole. Cherry pick the places you fish so that you can stay up on the rocks and out of the river. Fighting the willows usually means you are working water along a swift bank with little structure anyway.

Following these techniques will give you the opportunity to catch fish and have phenomenal days on the water, even during periods of high flow.
Story written by Greg Felt of ArkAnglers.

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