Hot days prompt fishing restrictions on Bitterroot River
Laura Lundquist
(Missoula Current) During these dog days, fishermen need to stay off the water in the afternoons to save trout in the upper Bitterroot river and other rivers as well.
As the summer has warmed up and a heat dome begins to settle over Montana, the rivers also warm. This means trouble for aquatic species, especially trout that rely on cooler water to stay healthy.
As the stream temperatures rise, cold-blooded fish become more physiologically stressed, because their body temperatures increase with the water temperature. When that stress is further increased by fighting for their lives on the end of a fishing line, some can end up dying even after being returned to the water.
For that reason, Montana Fish, Wildlife & Parks prohibits fishing during the heat of the day - between 2 p.m. and midnight - after stream temperatures have reached or exceeded a set temperature for three consecutive days. This is known as a “hoot-owl “restriction.
The water temperature that triggers the restriction is dependent on the species of trout in the river. Native trout such as Westslope cutthroat or bull trout are less tolerant of warm water than nonnative trout like rainbows.
Where bull trout are prevalent, the trigger temperature is 60 degrees, and rivers with large cutthroat trout populations have a trigger point of 66 degrees. All other rivers will go into hoot-owl restrictions when the temperature warms to 73 degrees.
While most rivers are still managing to stay somewhat cool, water levels have dropped significantly in the Bitterroot, Beaverhead, Jefferson and rivers, causing them to heat more during the day.
Between July 14 and 16, water temperatures in the Bitterroot peaked above 66 degrees. So starting Wednesday, hoot-owl restrictions are in effect for the stretch of the Bitterroot between Conner, where the West Fork comes in, and Veteran’s Bridge in Hamilton.
These restrictions will remain in place until the water temperature in the Bitterroot River stays below 66 degrees for three consecutive days, adequate flows are present and FWP announces the restrictions are lifted.
Over on the Beaverhead River north of Dillon, the water temperature at the Twin Bridges stream gage reached or exceeded 73 degrees for three days starting on July 14. So starting Wednesday, hoot-owl restrictions will be in effect for the Beaverhead River from Anderson Lane north of Dillon to the confluence of the Big Hole River north of Twin Bridges.
The Big Hole and Beaverhead rivers come together to form the Jefferson River, which also had water temperatures exceeding 73 degrees for three days starting on July 14. So starting Wednesday, hoot-owl restrictions apply on the entire Jefferson River.
Finally, the Madison River, which for the past several years has regularly suffered from low flows, has had water temperatures above 73 degrees since July 8. So the lower stretch - from the Warm Springs Fishing Access site to the mouth - has been under hoot-owl restrictions since July 12.
These restrictions will remain in place until the water temperature stays below 70 degrees for three consecutive days, adequate flows are present and FWP announces the restrictions are lifted.
The only other river under hoot-owl restrictions is the Sun River from the Highway 287 bridge north of Augusta to the mouth of Muddy Creek near Vaughn. The stream gage at Simms showed that daily stream temperatures broke 73 degrees starting on July 8.
With air temperatures predicted to peak out between 95 and 100 through early next week, it’s likely that hoot-owl restrictions will be needed on more rivers. Fishing organizations and guides recommend that, even on rivers without restrictions, anglers limit their fishing to early morning to keep Montana’s trout populations strong and healthy. Also, don’t “play” the fish for an extended time - that adds stress. Land it quickly, keep it wet and return it to the water as soon as possible.
Contact reporter Laura Lundquist at lundquist@missoulacurrent.com.