The first few times I saw flyfishermen on some local streams during spring runoff, I wrote it off to that strain of cabin fever that hits when the trees are budding but the water is still high and muddy from snowmelt. I subscribed to the belief that discolored streams only fished well with bait, and I wondered why those fishermen weren't doing what I was doing: searching out the lakes and tailwater rivers that are mostly immune to spring floods.

I found out why more or less by accident. Here in the northern Colorado Rockies, there's usually a brief spring dry-fly season that begins when the water warms sufficiently at the lower altitudes, before snow in the high country has begun to melt in earnest and swell the streams. When it starts and how long it lasts depend on the weather and the depth of the snow in the mountains, and it can end suddenly and definitively with the first hot spell.

My discovery arose from a simple matter of timing. If I drove 20 minutes to a stream only to find it off color, it was easy enough to turn around and go home, but if I drove for two hours I'd feel obligated to give it at least a half-hearted try. When, just by going through the motions, I began to pick up a few trout here and there, I realized I'd been missing out on some great fishing.

Dirty (Water) Tactics
The fact is, trout do well in runoff. In a normal spring flood, the water is comfortably cool and well oxygenated by the tumbling currents. The increased flow also dislodges aquatic nymphs and washes bankside terrestrials like grubs, worms, and beetles into the stream, so there's plenty for the fish to eat.

[NEXT "Story Continued"] Visibility is the main thing to look for when fishing high water. Stand in the middle of a bridge over a stream in runoff: The main channel will look like a brown, roily mess, but check along the banks. If you can see even a few rocks in the shallow water, string up your rod.

For flyfishing, the more visibility there is the better, but it's surprising how little you can get by with. I know it's plenty clear enough to fish if I wade into a stream and still faintly see the toes of my boots in knee- or even calf-deep water. If it's any cloudier than that, I'll lower my expectations, but since the stream is still full of food, the trout are still hungry, and there I am in waders, I'll usually give it a try. My standard rig is a brace of flies: a size 4 or 6 dark stonefly nymph, trailed by something like a size 12 or 14 mayfly or caddis larva. I'll use as much weight on the leader as it takes to get the nymphs to the fish. You don't want to snag bottom on every other cast, but if you don't hang up now and then, you're probably not fishing deep enough. And although I'm not a big fan of strike indicators, I'll probably use one. They're no fun to cast, but I like an indicator large and buoyant enough to act as bobber, suspending the nymphs in the current.

I usually have a few great days fishing the runoff every spring, but most trips are of the kind where, after an hour or so, it becomes obvious that two or three trout will be the best I can hope for. Still, there's something about catching even a few small trout from a stream few others will bother with until later in the season that makes me feel pleasantly sneaky, and if someone sees me and thinks I'm an idiot, so be it. They may be right-just not about fishing the flood.