THE DALLES, Ore.

Much as Lewis and Clark were obsessed with reaching the Pacific two centuries ago, Ken Karsmizki has an obsession of his own: To find and preserve as many of their campsites as possible.

He has identified one major campsite, the Lower Portage, near Great Falls, Mont., and is on the trail of others.

But the 53-year-old archaeologist and historian says time is running out for locating the other spots where members of the expedition camped on their 1804-06 "Voyage of Discovery" into the uncharted territories of the West.

Meriwether Lewis and William Clark left St. Louis in May 1804 and 3,700 miles later reached the mouth of the Columbia River in what is now Washington state.

As the 200th anniversary of their exploration approaches, interest is growing and Western states are beefing up tourism efforts. After the bicentennial passes, Karsmizki predicts interest will wane and funding will dry up.

Is his quest an obsession?

"The answer would be 'yes,"' said Karsmizki, who has researched the expedition for 15 years. Last March he came to the Columbia Gorge Discovery Center in The Dalles from the Museum of the Rockies in Bozeman, Mont. His effort is supported by an arrangement with The Discovery Channel plus private and corporate funding.

Karsmizki estimates the Lewis and Clark expedition set up camp at some 600 sites. Using the explorers' journals and some high-tech satellite help, he is trying to find evidence of their stops along the way.

"How do you preserve it? First, you have to find it. Tomorrow it may be a parking lot," says Karsmizki, sitting in his cluttered office in this Columbia River town, where he believes one of the camps was located.

For the past 15 years, he has examined possible camping sites along the Lewis and Clark route in Montana, Oregon, North and South Dakota, Idaho and elsewhere.

"People have had access to Lewis and Clark's journals for some 200 years. The next step is not to focus on what was written, but on archaeology. There must be much that they did that never made it into their journals," he said.

Karsmizki and his team get down on hands and knees and dig for signs of the explorers.

They are aided by satellite imagery from the National Aeronautics and Space Administration and data from the Air Force Research Laboratory. In some cases, the technology can reduce a potential dig site from several square miles to a matter of acres.

At Lower Portage, the campsite near Great Falls, Karsmizki has found a tent stake, butchered buffalo bones, a rifle flint and campfire residue that carbon-date to the Lewis and Clark era.

The expedition spent the winters of 1804-05 at Fort Mandan, N.D., and 1805-06 at Fort Clatsop near Astoria, Ore. A replica of Fort Clatsop was built in 1955, but archaeologists say it probably is not at the exact site of the original.

"There have got to be things they left behind," Karsmizki said, adding that even the forts themselves, which likely rotted in place, should be detectable.

So far, he's found a musket ball near where he believes Fort Clatsop stood. But National Parks Service archaeologists question whether the lead is either a musket ball or related to Lewis and Clark.

He also is looking for the site of Fort Mandan at Washburn, N.D., Fort Manuel in South Dakota, where the guide Sacajawea died and Fort Ramon in Montana, a fur-trading post some of the expedition members were involved in later.

And he hopes to find a boat that was carrying specimens Lewis and Clark were sending back to President Jefferson when it sank in Chesapeake Bay.

But he seems most enthusiastic about the possibilities of the Lower Portage and the Upper Portage, which are 20 miles apart on the Missouri River. The expedition had to carry everything from one camp to the other because of the waterfalls.

At the Lower Portage, he said, they made carts to carry equipment around the falls.

"There must be chips and sawdust," he said. "Everything came off the boat" to be carried around the falls, increasing chances that something was left behind.

At the Upper Portage, the expedition buried a collapsible iron boat frame that was to have been covered with animal hides. It didn't work and the expedition apparently had planned on coming back for it on the return trip.

It would be the single most important artifact of the expedition, he said, but it has remained elusive.

"I feel they probably did not pick it up," he said. "The expedition was broken into four groups at that point. It weighed 220 pounds and they didn't have the manpower."

"They wrote that the boat failed because they had taken the hair off of the buffalo hides they used to cover it," he said. "That hair has to be there."

The remains of the boat, he said, could be displayed.

"When you are an archaeologist, you want information," he said. "If you're the public, you want objects, you want to see it."