Rivers and lakes across the Northwest -- from Yellowstone to Montana -- have lost most of their trout due to extreme drought conditions. To preserve dwindling populations, state authorities have implemented a variety of restrictions that leave recreational fly fishers in a lurch.

Why This Matters

Montana and the Yellowstone area are places that thrive on outdoor recreation and fishing is a major part of their economies. In Montana alone, anglers of all kinds spend nearly $500 million a year, according to the American Sportfishing Association. A new coalition of businesses, fly fishing guides, and environmentalists wrote in a letter: "If water quality in our rivers continues to decline, and our rivers themselves dry up, these negative changes will also tank our state's robust outdoor economy that directly depends upon vibrant cold water fisheries."

The drought has affected sport fishing in California and Colorado as well. Northern California's Iron Gate Fish Hatchery could not stock the river with young salmon because low flows and warmer water temperatures have increased parasite infections. A first in its 55-year history. Colorado has closed off a 120-mile-long stretch of the Colorado River for fishing in the north-central region for similar reasons.

Big Fish In Increasingly Small Ponds

Trout like to live in water that is between 45 and 60 degrees Fahrenheit. Due to warming weather, water levels are lower and temperatures are rising faster, well into the low 70s. At these higher temperatures, there is less oxygen in the water and the trout become sluggish and stop feeding. If water temperatures surpass 75 degrees, the fish are at risk of die-off. These dangerous conditions have been further exacerbated by water pollution causing algae blooms that prevent trout from feeding and breathing effectively.

Around Montana, trout have been dying en masse -- their corpses floating in rivers. The numbers of brown trout look particularly dismal. In 2014, the number of brown trout per mile at a popular fishing area on the Big Hole River was 1,800. This May, a census of the same area found only 400 brown trout per mile. Meanwhile, trout numbers in the Beaverhead River have dropped from 2,000 to 1,000 per mile. And this data was collected before the summer, when extreme heat and dryness set in.

In addition, Yellowstone National Park announced that it would shut down fishing on its rivers and streams after 2pm Saturday until sunrise the following day, as a result of 68-degree water temperatures and extremely low river flows.

Ironically, wildfire smoke on the West coast is blocking sunshine on the rivers and helping to prevent further warming. Though it may not be enough to save the struggling trout populations.

All in all, the situation is looking dire. "Between early season fish kills, unnaturally warm water temperatures and low trout numbers, it's an all hands on deck moment," John Arnold, owner of Headhunters Fly Shop in Montana told the New York Times.