Warm Waters, Low Flows Trigger Early Hoot-owl Restrictions on Montana, YNP Rivers

As locals and visitors in Greater Yellowstone converge on area rivers for hot-weather reprieve, fisheries across the area are feeling the heat.

Since the early 2000s, Montana Fish, Wildlife and Parks has been enforcing what are known as hoot-owl restrictions and closures on rivers to alleviate stress caused by angling pressure on fisheries impacted by warming river temperatures and lower streamflows. FWP typically enacts these closures in late July or early August, which are typically the hottest weeks of summer.

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This year, the combination of a below-average snowpack and record-breaking temperatures across the West in July has prompted earlier-than-usual restrictions on 17 western Montana rivers. Some areas in northwest Montana that have never required closures are also experiencing dangerously high water temperatures.

On July 24, FWP implemented hoot-owl restrictions on the North Fork of the Flathead River, marking the first time that restrictions have been applied in the Flathead River drainage. These restrictions, which prohibit fishing from 2 p.m. until midnight—when water temperatures peak—aim to give fish much-needed relief from warmer water and angling pressure.

National Weather Service data shows temperatures in northwest Montana soared as much as 10 degrees above average in July, with minimal precipitation.

Pat Saffel, Region 2 fisheries manager for FWP, told Mountain Journal that water temperatures are typically warmest in Montana from the third week of July to mid-to-late August. “This year we began restrictions early, in the first few weeks of July, and they are likely to continue through the rest of the summer,” Saffel said. “Once we implement restrictions, we usually keep them in place; otherwise, we end up chasing our tails with weather systems moving through.” 

Hoot-owl restrictions were placed on most rivers in southwest Montana in the first two weeks of July due to rising temperatures affecting rainbow and brown trout.

“Fish become stressed as water temperatures rise,” Saffel explained. “Being cold-blooded animals, they have specific temperature preferences. We use different criteria for implementing restrictions depending on the river and the species. For trout, that’s 73 degrees for three consecutive days.”

Rivers that drop below the fifth percentile of their average flow will also be closed to fishing.

In a July 12 press release, Yellowstone National Park announced fishing closures on three rivers inside the park—the Madison, Firehole and Gibbon—along with their tributaries in order to protect native and wild trout fisheries as water temperatures exceed 68 F. 

Anglers can find a complete list of Yellowstone National Park river closures and restrictions on the National Park Service website. Montana river closures and restrictions are listed on the FWP website.

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