Warming rivers prompt fishing restrictions in western Montana

Fourteen rivers in western Montana and a handful of rivers inside the borders of Yellowstone National Park are under restrictions or closures as biologists seek to reduce angling-related sources of fish mortality.

As of July 18, Montana Fish, Wildlife and Parks has closed portions of the Madison, Clark Fork, Gallatin, East Gallatin, Beaverhead, Ruby, Shields, Smith and Sun rivers to angling after 2 p.m. to protect fish during the hottest hours of the day. A stretch of Rock Creek, a tributary of the Clark Fork River, is also subject to a hoot owl closure and river-wide hoot owl closures are in place on the Big Hole, Bitterroot and Jefferson rivers. The Madison River above Hebgen Reservoir is closed to all fishing, as is the Saginaw Bridge to Skinner Meadows Road stretch of the Big Hole. FWP initiates hoot owl closures when river temperatures reach 73 degrees for three consecutive days and uses angler pressure and flow-based criteria when considering full closures. Trout are particularly susceptible to disease spread and other sources of mortality from late July through late August, when meager flows, rising temperatures and low dissolved oxygen levels converge. Water temperatures above 77 degrees can be lethal to trout.

On July 11, Yellowstone National Park initiated full fishing closures to protect aquatic ecosystems inside its boundaries. The Madison, Firehole and Gibbon rivers and their tributaries are closed to all fishing. Park officials consider closing rivers inside its borders to fishing when water temperatures hit the 68-degree mark and will revisit the closures when those temperatures cool and flows return to “more typical summer conditions.” Additional closures may be coming, park officials noted.

The announcements come about a month after FWP hosted a virtual town hall to alert the angling public to rapidly declining streamflows across much of the state. Biologists attribute diminishing streamflows to the loss of much of the state’s near-average wintertime snowpack in May. 

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“As things continue to drop … we’ll continue to work with water users on where we can find conservation measures to keep as much water as we can in the river,” Region 3 Fisheries Manager Mike Duncan said at the June 11 meeting. Conditions are shaping up to be very similar to 2021, he added. That year, Montana Gov. Greg Gianforte issued a drought-related disaster declaration on July 1 and more than 15 rivers were subject to some form of angling restriction or closure by mid-August.

Other FWP biologists observed that several reservoirs in the state never filled this spring and cautioned anglers and fly-fishing guides to prepare for limited access to reservoir boat ramps at places like the Tiber and Gibson reservoirs.

As of July 17, nearly 20 western Montana rivers were within the 10th percentile for low flows, including blue-ribbon fisheries such as the Big Hole, Blackfoot, Madison and Missouri rivers as well as the Clark Fork and one of its largest tributaries — Rock Creek.