Arkansas River
Hatch Chart 2025

The Arkansas ("Ark" to locals) isn’t just Colorado’s longest river—it’s one of its most diverse. Stretching from Leadville to Pueblo, the Ark runs through freestone canyons, alpine valleys, and foamy riffles that serve as a buffet for wild browns and rainbows.

This river doesn’t coddle. Conditions change fast. Hatches vary by stretch. But with the right flies—and a little timing—you’ll have trout rising, slashing, and hammering your patterns all season long. Below is your month-by-month cheat sheet.

That’s why knowing the hatch matters. Below is a month-by-month breakdown of the most reliable bug activity on the South Platte, plus our top fly picks for matching the hatch. Whether you’re stalking sipping rainbows or dredging for grudging browns, this chart is your riverside cheat sheet.

This river's a study in contrasts. At 10,000 feet, midges rule. In Bighorn Sheep Canyon, it’s hoppers and stoneflies. Always check flows, match size first, and fish the water in front of you—not the hatch chart in your pocket. Then go back and match both.