Fly Fishing Montana on the Boulder River in May
Runoff season begins in earnest sometime in early May or late April on the Boulder River. Although water clarity typically remains favorable, raging flows make fishing difficult and even dangerous at times.
Expect daily flow fluctuations early on in the runoff as river levels rise and fall along with the daily temperatures in the headwaters. As with many Montana Rivers, trout fishing is generally slow as water levels rise – even during mid-summer following a heavy rainstorm. Sparring the occasional, significant cold front which quickly pauses the runoff on the Boulder River, Montana fly fishing efforts are best directed elsewhere in May.
Boulder River Fly Fishing Hatches in May
March brown, green drake, and BWO mayflies hatch throughout May. Thick hatches of Mother’s Day caddis are typically present during the early stages of the Boulder River runoff. Expect surging river flows and difficult fishing conditions despite abundant insect activity.
Boulder River Fly Fishing Techniques in May
Elevated river levels create difficult and dangerous conditions for both floating and wade fishing. Nymph fishing with heavy stonefly and San Juan Worm combinations through deep pockets and next to the bank can produce plenty of trout in these conditions. However, access to the river is very limited during high water and dangerous in the spots where permissible.
Rapid, sudden drops in streamflow following cold fronts can create windows of highly productive fly fishing on the Boulder River in May. As flows drop and stabilize, nymph fishing with stonefly patterns next to the banks and in deep pockets can be terrific. Wait for flows between 800 and 1500 CFS before attempting to float the Boulder. Floating anglers should be prepared for dangerous obstructions in the river following any high water events.
Bozeman Fly Fishing Guides Pro Tip:
Watch for rapid and sudden drops in streamflow for productive Boulder River fly fishing in May following significant cold fronts. As flows drop and stabilize, nymph fishing with stonefly nymphs next to the banks and deep pockets can be terrific. Wait for dropping flows between 700 and 1200 CFS, floating anglers should be prepared for dangerous obstructions in the river following any high water flows.
Boulder River Fly Box in May
Boulder River Fly Fishing Trips in May
We focus our trips on the Madison and Missouri Rivers during May and early June. With over two decades of experience guiding and outfitting fly fishing trips in Montana, Fins and Feathers fly fishing guides can be relied on to safely and effectively navigate and fish high water conditions.
Boulder River fishing trips are best reserved for mid-June through mid-July when water levels are between 800 and 1500 CFS. May is not the time for a guided fishing trip on the Boulder River.
Contact us to learn more about the various runoff season fly fishing options during May and June. Guided fly fishing day trips can be secured online, via e-mail, or by calling us at 1-406-468-5019.