ON THE SKYKOMISH RIVER — After expertly maneuvering a raft through a series of rapids on the Skykomish river, Ross Freeman jumps out after it suddenly runs aground in a shallow spot.

“This is rafting of the future — walking,” Freeman says, half in jest, as he drags the 14-foot raft over to more floatable waters.

Freeman, associate director of conservation for the Northwest regional office of American Rivers, has been rafting for 15 years. While he doesn’t expect the Skykomish to run dry anytime soon, he said that as more winter precipitation arrives as rain instead of snow, there will be less snowpack to keep water levels high enough to be raftable.

“In terms of recreational impact, we’re going to see rivers dropping sooner and we’re going to have shallower rivers earlier in the summer,” he said.

That means the state’s numerous outdoor enthusiasts — and those who travel here from afar to enjoy hiking and paddling and other fresh-air pursuits — may need to adjust their vacation schedules in the future. Skiers may face a shorter season on the slopes, hikers could have a hard time accessing trails, and rafters like Freeman might bottom out earlier than they’d like.

That possibility doesn’t go unnoticed with officials in the state, where last year, tourism and recreation was a $13 billion industry.

“Of course, our natural environment plays a large role in people choosing to visit and live here,” said Penny Thomas, spokeswoman for the state’s Department of Community, Trade and Economic Development. “It’s safe to say that any significant impact to our recreation areas and natural resources could affect the total industry.”

A 122-page state-commissioned report last November by the Climate Leadership Initiative at the University of Oregon found that among other economic impacts, recreation and tourism in Washington state will be impacted by climate change in varying ways.

So while backpackers may have a longer season due to warmer temperatures, they also may find areas inaccessible due to more wildfires brought on by drought.

“Recreational opportunities are going to shift around,” said Bob Doppelt, director of the Climate Leadership Initiative at the University of Oregon, who oversaw and contributed to the report. “Some will be impacted more than others in different years, but over time, as it warms and the snowpack is affected and stream flows are affected, people will see the recreational opportunities diminish or become more costly.”

A recent report by the Washington Trails Association found that a third of the state’s residents consider themselves hikers, backpackers, trail runner or climbers. The organization has done repairs on miles of trails that were severely damaged by record rainfall during last year’s fall and winter storms.

“Hikers are going to get an up close and personal view of the effects of climate change on the backcountry, and they’re not going to like it,” said Jonathan Guzzo, advocacy director for the trails group.

Guzzo said that shrinking glaciers will mean reduced water runoff, and hikers could be faced with problems of finding water. Also, he said that more plants and flowers might die off in the high country, and bug infestations of trees could reach up into the hillsides as it gets warmer.

Aside from all the secondary effects, any change to the glaciers will be a visual loss for hikers.

“Hikers are accustomed to seeing huge, amazing glaciated peaks,” he said. “We don’t know how long it’s going to be before those sights are dramatically less common.”

The 2006 state report also found that as the temperature gradually increases, the direct costs of fighting wildfires could be greater than $75 million a year by the 2020s, a 50 percent increase from current costs, and which does not take into account the costs of lost timber value.

But some caution these reports shouldn’t be considered definitive.

“Too often they are misused because what happens is they exaggerate impact on snowpacks and the amount of economic impact,” said Todd Myers, director of the Center for Environmental Policy at the Washington Policy Center, a conservative think tank.

“There is no question that temperature has increased in recent years,” he said. “It’s pretty clear CO2 has contributed in some way. The hard part is to judge how big an impact it is and what the appropriate response is so you’re not doing harm to the economy in one sector in order to help another.”

Rob Fimbel, chief of resource stewardship for the state park system, said the state has surveyed more than half of the 120 parks to get a baseline of vegetation and plants, so that they can measure the impacts of climate change.

Fimbel said that another concern is impact to the state’s coastal parks, which “are likely to see some fairly dramatic changes if the sea level rises and storm intensity increases as projected.

“It will be a constant battle to maintain the habitat,” he said.

The state’s ski industry, which saw a record low snow year for the 2004-2005 season, is also taking note.

“We realize the chances are we’re going to have lower snow years,” said John Gifford, president of Ski Washington, who said that while he believed the 2004-05 season was an anomaly, resorts aren’t taking the recent good snow years for granted.