MONTANA — Wildlife officials across the U.S. West imposed widespread afternoon fishing restrictions in summer 2026 due to record heat and low water levels threatening fish populations. Yellowstone National Park expanded afternoon fishing restrictions to the entire park on Wednesday.

Montana wildlife officials broadened afternoon fishing restrictions to cover 1,200 miles (1,931 kilometers) of rivers on Wednesday. The restrictions aim to reduce stress on species including trout. Wildlife officials are banning fishing during certain hours on rivers and streams across the U.S. West.

Record heat this summer has driven water temperatures to lethal levels for fish in the U.S. West. A heat wave in the Southwest is expanding north into the Rocky Mountains and east across the High Plains. Lower water levels cause rivers to heat more rapidly. Many reservoirs in the region are at near-record lows.

The fishing restrictions follow an exceptionally dry winter and widespread drought. Warm water contains less oxygen, making it harder for fish to breathe, and slows their growth. Temperature-stressed rainbow or cutthroat trout can die if they are out of water even briefly, according to experts.

Colorado has imposed fishing restrictions this summer on 19 rivers totaling 635.5 miles (1,023 kilometers). Colorado state officials describe the current fishing restrictions as unprecedented. Colorado Parks and Wildlife (CPW) issued an emergency fish salvage order on July 21, 2026, lifting all bag limits and fly-and-lure restrictions on six major rivers to mitigate fish mortality during extreme heat, as documented in a July 2026 Outdoor Life report.

Drought and warm waters in the mid 70s Fahrenheit (23 Celsius) killed a massive number of fish on the Yampa River in Steamboat Springs, Colorado. Montana Fish, Wildlife & Parks reported that 1,200 miles of rivers in the state were under afternoon fishing restrictions by August 2026, representing a 40% increase from the 2016 Yellowstone River closure of 183 miles.

In 2016, wildlife officials closed 183 miles (295 kilometers) of the Yellowstone River to fishing, rafting, and other activities to prevent the spread of a parasite. Yellowstone National Park has restricted fishing due to high water temperatures during five of the past six years.

Mike Wever, a 62-year-old California resident, fished on the Yellowstone River near Livingston, Montana, on July 31, 2026. "Not very cold," said Mike Wever after dipping his hand into the Yellowstone River. "It’s great for us to have this resource, but we have to manage it," said Mike Wever regarding the fishing closures.

"Closures have become very common over the last decade plus, some might even say very routine from late June through early September," said Adam Strainer, administrator of the fisheries division at Montana Fish, Wildlife and Parks. Dan Gigone, who runs Sweetwater Fly Shop along the Yellowstone River in Montana, noted the warming trend. "I’ve been here 22 years and this is the warmest stretch I remember," said Dan Gigone.

"People are realizing August is a crapshoot here in terms of whether you’re going to be able to fish and how good the fishing will be," said Dan Gigone. Researchers found more days when rivers were warm enough to stress cold-water species like bull trout. "River heat waves" are increasingly happening in snow-dominated areas such as the northern U.S. and the Rockies, according to a study published last year.

The scale of the 2026 restrictions shows a shift in river management across the West. Montana's 1,200-mile coverage represents a significant expansion from the 183 miles closed in 2016. This increase reflects worsening conditions driven by drought and heat. Colorado's emergency orders further demonstrate the regional nature of the crisis.

Experts link these changes to broader environmental patterns. Li Li, a professor in civil and environmental engineering at Pennsylvania State University, stated that climate change is changing the size and timing of the mountain snowpack, and that’s contributing to river heat waves. Todd Tanner of the School of Trout in Bigfork, Montana, added that the window for those trips seems to be growing narrower as conditions get hotter, drier and more wildfire-prone. A study titled Household livelihoods and conflict with wildlife in community-based conservation areas across northern Tanzania was published in 2015 in Oryx.

Why It Matters

The unprecedented scale of 2026 fishing restrictions across the U.S. West signals a shift from isolated closures to routine summer management driven by drought and record heat. With water temperatures reaching lethal levels that kill fish rapidly, these measures aim to prevent widespread mortality of cold-water species like trout. As river heat waves become more frequent in snow-dominated regions, the window for safe fishing narrows, fundamentally altering access to these resources for anglers and local businesses.