SALMON, Idaho, Aug 18 (Reuters) - Wildfires sweeping across the western United States are straining communities that depend upon the summer tourism season, as recreation sites catch fire, campgrounds close and outdoor activities such as river rafting are disrupted.
In the mountains of central Idaho, where whitewater rafting has replaced logging as an economic mainstay, blazes are curtailing trips on rivers whose world-class rapids draw an international crowd of thousands from June through August.
Tourists who booked rafting trips months in advance have been canceling their reservations, spooked by fast-changing blazes that have produced a smoky haze and led to road blockages.
"We've had nothing but cancellations," said Lorali Simmons, owner of River Shuttles, a business in Salmon, Idaho, that shuttles vehicles for boaters on the Middle Fork and the Salmon River's wild and scenic corridor.
The wildfires that have scorched 80,000 acres (32,375 hectares) of mountain pine forests in east central Idaho stranded 300 Middle Fork rafters northwest of Salmon this week after falling rock closed the only road to the site.
Dozens of fires are burning out of control across parched Western states, including California, where blazes have encroached on national parks.
A survey released this week by the U.S. government shows the number of Americans engaging in outdoor recreation rose last year for the first time in three decades. At the same time, remote, sparsely populated communities in western states have tried to remake themselves as gateways to natural resources that attract visitors.
In recent years, fires, floods and heat waves have taken a toll on a tourism industry that the Outdoor Industry Association says generates more than $35 billion combined for Idaho, Colorado and California annually.
There is no detailed accounting of the extent of tourism losses from fires and other natural disasters, but tour operators say they worry about losses due to fires as well as those that arise from cancellations by worried customers.
"It could potentially be devastating," said Kristin McMahon of Idaho Rocky Mountain Ranch in Stanley, a base for dozens of river outfitters and key launch sites for the Middle Fork Salmon River through the Frank Church River of No Return Wilderness.
Wildfires have burned 6.5 million acres (2.63 million ha) across the United States so far in 2012, about 1.5 million acres more than the 10-year average for this time of year, according to the National Interagency Fire Center.
In Idaho, campground closures and disrupted river runs began earlier this month and have stretched southwest from the state capital Boise through the Sawtooth Mountains near Sun Valley.
August is critical for the 175 licensed outfitters who offer float and jet boat rides in Idaho, which has more river miles than any other state except for Alaska, said Grant Simonds, head of Idaho Outfitters and Guides Association.
"River outfitting operations pay their bills and overhead expenses with June and July; August represents the 5 to 10 percent profit they stand to net," he said.
In Colorado, two huge blazes in June all but snuffed out tourism in some areas. The 88,000-acre (35,612-ha) High Park Fire northwest of Fort Collins burned onto the Roosevelt National Forest, one of the most visited U.S. national forests.
Large sections of the forest, including certain campgrounds and trails, remain closed, said U.S. Forest Service spokeswoman Reghan Cloudman.
There was "absolutely an impact" on recreational activities such as rafting on the Cache La Poudre River, mountain biking and hiking, she said.
In southern Colorado, the Waldo Canyon Fire forced the evacuation of 5,000 residents of Manitou Springs, situated at the foot of Pikes Peak and other tourist attractions near Colorado Springs.
"It's been far worse than we expected," Roger Miller, chief operating officer of the Manitou Springs Chamber of Commerce, said of the fire's impact on the town.
Miller said that even though the blaze never reached Manitou Springs, the fire cost $2 million in tourist revenues, cut lodging reservations in half, shuttered two businesses and placed another 15 at risk of closure.
In northern California, two fires caused by lightning have blunted tourism in the area around Lassen Volcanic National Park. Sharon Roberts of the nearby St. Bernard Lodge said she had received numerous cancellations.
"It's tough. It's going to be tough for the whole community." (Additional reporting by Keith Coffman in Colorado and Ronnie Cohen in California; Editing by Alex Dobuzinskis and Paul Simao)