Fishing the North Fork of the Flathead from 2 p.m. to midnight is now illegal due to high water temperatures

After more than two weeks of unprecedented heat, Montana Fish Wildlife and Parks has announced “hoot owl” restrictions on the North Fork of the Flathead River. 

It’s the first time ever that the restrictions, which prohibit fishing from 2 p.m. to midnight each day, have been enacted on the North Fork. They went into effect today (July 24).

The restrictions have become almost commonplace on many big name rivers in Southwest Montana. 

Region 1 spokesman Dillon Tabish said water temperatures on the North Fork have been at or above 66 degrees almost daily since mid-July, when the heat wave first started. 

The upper water temperature threshold for westslope cutthroat survival is about 66 degrees, studies have shown.  

Fish typically can find refugia like seeps and springs or near the inlet of cooler tributaries when temperatures get this warm. 

On Sunday, air temperatures reached 100, a record high for the day. The Washington Post reported that Sunday and Monday were the warmest recorded days in the history of the world. Locally, the high temperature has been above 90 for 17 consecutive days at the Glacier International Airport.

FWP has been posting the restrictions at fishing access sites on Wednesday, trying to inform people who may not have heard about it yet, Tabish said. 

FWP received approval from the Montana Fish and Wildlife Commission and collaborated with Glacier National Park on the restriction, which will extend the full length and both sides of the North Fork from the U.S.-Canadian border to the confluence with the Middle Fork Flathead River near Blankenship Bridge. 

Fishing restrictions are designed to protect fish that become more susceptible to disease and mortality when conditions, such as low flows and high water temperatures, combine with other stressors, including catch-and-release fishing, FWP notes. 

They are also concerned about other area rivers, including: 

Middle Fork Flathead River 

South Fork Flathead River 

 Mainstem Flathead River upstream of Old Steel Bridge in Evergreen 

 Swan River 

 Thompson River 

FWP is not recommending hoot-owl restrictions at this time on these other stretches of water but is encouraging anglers to voluntarily limit their fishing to the morning hours when water is coolest and fish are less stressed. Additional fish stress and mortality can result from human handling when trout are caught and released by anglers. 

FWP will continue to monitor conditions on these rivers and make adjustments as needed, the agency said in a release.

FWP's Statewide Fisheries Management Plan identifies different temperature criteria for different species of native trout. The temperature criterion for westslope cutthroat trout is met when water temperatures reach or exceed 66 degrees Fahrenheit for three consecutive days. The criterion for bull trout is 60 degrees, also for three consecutive days. 

For a list of statewide restrictions and closures, visit https://fwp.mt.gov/news/current-closures-restrictions.