Warming rivers prompt fishing restrictions in western Montana

Associated Press

a day ago

Nearly a dozen 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.
On July 9, Montana Fish, Wildlife and Parks announced that portions of Upper Rock Creek, the Clark Fork River, the Bitterroot River and the entirety of Silver Bow Creek are closed to angling after 2 p.m. to protect fish during the hottest hours of the day. The previous day, hoot owl restrictions were announced for sections of the Ruby, Big Hole, Beaverhead and Smith rivers and for the entirety of the Jefferson River. The Sun River and the Madison River, perhaps the state's most popular angling destination, were placed under hoot owl closures particularly early this year — July 2 for the Sun River and June 19 for the Madison River above Hebgen Lake.
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 border 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.
'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 14, approximately 20 rivers in western Montana 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. The Dearborn River stream gauge near Craig, which has 55 years of records, was sitting at an all-time low, producing just 16 cubic feet per second of flow.
Rivers across the state are experiencing near-record-low flows with additional challenges expected.
In a follow-up conversation with Montana Free Press on Monday, Duncan noted that water quantity and fish health are closely linked.
'When we have water, almost all of these fisheries respond favorably,' Duncan said, going on to describe suboptimal flows as one of the 'major limiting factors' in overall trout population trends. Duncan added that additional restrictions and closures could be announced as rivers around the state continue to dwindle and heat up.
FWP's Current Restrictions and Closures page is the best source of information for most of the rivers in the state. Yellowstone National Park notices angling closures inside its borders on the Plan Your Visit section of its website.
About one-third of the state is in moderate or severe drought, according to the U.S. Drought Monitor. On Wednesday, the Governor's Drought and Water Supply Advisory Committee will meet in Helena and virtually to discuss current conditions and drought mitigation measures.
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This story was originally published by Montana Free Press and distributed through a partnership with The Associated Press.