You can't get much farther into Washington's wilderness than Hoh Lake.

The small lake is cupped by steep, rocky slopes high in the Olympic Mountains, and the signs of civilization include a crude trail and the occasional campsite.

But even there, the turquoise water, along with the fish, snow, mud and trees, all bear the toxic fingerprints of the industrial world.

A massive new study of 20 Western national parks and monuments, including Washington's Olympic, Mount Rainier and North Cascades parks, found traces of everything from pesticides and mercury to man-made industrial chemicals in some of the most remote and untouched places in the country.

"We all perceive these as being the last pristine areas in the country, and we know now they are not perhaps as pristine as we thought," said Olympic National Park spokeswoman Barb Maynes. "Airborne contaminants circulate everywhere."

The findings, released Tuesday, are prompting parks to consider posting notices to fishermen who might eat mercury-tainted trout. They're also raising some concerns about the effects these chemicals, even in tiny amounts, might have on the wildlife.

The National Park Service issued a statement saying people are unlikely to eat enough contaminated fish to be at risk.

But "if there are fishermen consuming fish in the park, we need to make sure they are aware of that," Mount Rainier biologist Barbara Samora said.

Highest pollution in other states

In lakes at both Olympic and Mount Rainier national parks, some brook trout had mercury levels above the Environmental Protection Agency (EPA) threshold for a possible health effect for recreational fishermen. That means at least one in 100,000 people eating some of the fish — every day for their entire life — would get cancer from it.

While most of the fish caught for the study appeared healthy, some male fish at Rocky Mountain National Park (Colorado) and Glacier National Park (Montana) had female ovary tissue in their testes. Such fish have been linked to the presence of chemical pollution. Male fish caught at those two parks, as well as one caught at Mount Rainier, also had high levels of a protein usually found in female fish.

While pollution levels at different parks varied depending on the chemical, the highest overall levels were at Rocky Mountain and Glacier, as well as Sequoia and Kings Canyon national parks in California, said Dixon Landers, an EPA scientist who led the six-year study.

The chemicals trace back to farming, nearby factories, even global activities like coal-fired power plants that puff mercury into the atmosphere, Landers said.

The pollution is carried in the air, riding on snowflakes, raindrops and dust particles. Researchers found 70 different chemicals, including heavy metals like mercury; pesticides such as chlorpyrifos; and the long-banned pollutants DDT, a pesticide, and industrial PCBs.

While it's not clear what all the sources are, Landers said more pollution was found inside parks where there was a lot of farming nearby. But he said the reason wasn't known yet.

Warren Cornwall: 206-464-2311 or wcornwall@seattletimes.com. Staff reporter Lynda V. Mapes and The Associated Press contributed to this report.