Usually in late July, early August, the fish are hanging out in the deep holes of the river, keeping cool, and chomping the dry flies tossed their way. July’s parade of 90-plus degree days and 80-degree evenings kept the water temperatures creeping up.
“For this time of year,” says fishing guide Aaron Manuel, “it’s 3 degrees warmer than I’ve ever seen.” Manuel grew up in the area, and has worked as a fishing guide along the Flathead and other area rivers for nine years. He says he was finding fish in shallower, fast moving water in July, and they weren’t too eager to chase any flies.
On July 27 Montana Fish Wildlife and Parks closed catch-and-release bull trout fishing for the South Fork of the Flathead River. Fisheries biologists measured afternoon temperatures of 68 degrees Fahrenheit. They say water warmer than 60 degrees stresses bull trout.
“I temped it at 68 degrees,” Manuel recalls, “and I’ve never seen it above 65, maybe 66 by the end of August.”
“I don’t know if we’ve ever had a temperature-related fishing closure,” says John Fraley, thinking back on his 27 years with FWP. Fraley works as the public information officer for the region. He says if a river hits 73 degrees three days in a row, they close it.
In the case of the South Fork of the Flathead, FWP stepped in earlier because of the recovering bull trout population. Regional fisheries manager Jim Vashro says the bulls are five to eight weeks away from spawning and the combined stress of warmer water and catch and release could hurt their spawning success.
“It’s akin to us hiking at high altitude,” says guide Eric Bjorge of Two Rivers Gear in Bigfork. “The higher we are, the less oxygen we have, the higher the water temperatures, the less oxygen the fish have.” Bjorge has worked 15 seasons as a fishing guide in the area.
The string of days with temperatures in the mid-90s had him shake up his trip schedules. He centered fishing trips around the morning hours, when the water’s cooler, and the fish more active.
“If they swim away slow, it might be time to stop fishing.” Bjorge says with the warmer water “it makes it a lot easier for a fish to get winded to the point that it can’t recover.”
The Flathead River has an advantage over other Montana rivers: cold water from Hungry Horse Dam.
“It keeps us from having the closures that the other rivers are susceptible to,” says Bjorge. He and Manuel both cite the cold influx of water in the low 60s as helping to keep the Flathead cooler. There’s another factor though, dipping overnight temperatures.
“There’s about three to four weeks in there that are pretty tough,” Bjorge explains, “then we start getting cool nights, and the cool water comes.”
In Region 1, the Thompson River saw restrictions put in place for the earliest time on record. It closed on July 11 for any fishing between 2 p.m. and midnight. FWP measured water temperatures above 73 degrees and water flowing at about half what it usually does in mid-July. In the hot, fiery summers of 2001 and 2003 FWP closed the river, but none went into effect until the end of the month.
These closures and restrictions will stay in effect until the water temperature drops, typically in late August, early September. But typically, the water isn’t in the upper 60s in late July. For now, anglers remain optimistic.
“Our springs are getting a little bit nicer, earlier,” says Bjorge, “but summer sure seems to be hot.”