PORTLAND, Ore. (AP) -- The U.S. Forest Service is testing the public's tolerance for its confusing mishmash of land passes and fees with a plan to toughen enforcement this summer.

Entrance fees at national parks and campground fees in national forests have long been accepted by most who use them, but it's not as clear how willing they are to pay for such simple pleasures as day hikes.

Critics charge that the recreation fees are poorly designed, but land agencies say the public supports the fees that have raised millions of dollars.

Congress created the Recreation Fee Demonstration Project in 1996, and instructed the Forest Service, National Park Service, U.S. Fish and Wildlife Service and U.S. Bureau of Land Management to test ways of collecting new and higher fees.

In the Northwest, the Forest Service levied nearly 20 different charges. A fee plan unveiled last year, the Northwest Forest Pass, costs $5 a day or $30 a year and is required for parking at many trailheads in national forests and North Cascades National Park in Washington.

It is required for overnight camping at some backcountry sites around Mount St. Helens.

The pass combined fees at many forests, but it remains just one of a confusing mix of more than 10 federal and state land passes available in the region.

Buying annual passes for two people to visit all federal and state land and visitor centers in the Northwest would cost well over $100.

The Forest Service reported to Congress that forest users overwhelmingly support the recreation fees.

Some researchers, however, say the conclusion is based largely on surveys taken at fee sites of people who have opted to pay the fees. It overlooks those who cannot or will not pay them.

The Forest Service, meantime, has muffled one of its scientists whose research suggested that fees drive low-income users off national forests.

In a mail survey of Vermont and New Hampshire households, Thomas Stevens, a University of Massachusetts at Amherst researcher, and Thomas More, a Forest Service researcher in Vermont, conducted the first broad survey of the way recreation fees affect all forest visitors.

One of every four low-income families visited national forest less often to avoid the fees, the study found.

Soon after the paper emerged, the Forest Service barred More from talking to the press, a prohibition that continues. The agency issued "talking points" to its spokespeople around the country dismissing the findings as "statistically insignificant."

"The Forest Service is very sensitive about this," said Stevens. "They have staked their future on this fee program. They do not welcome information that raises questions about it."

It is unclear whether recreation fees have affected overall forest visitor numbers, because even Forest Service officials acknowledge that their recreation counts are inconsistent and unreliable.

A University of Montana report on recreation in the Northwest found that the Willamette National Forest in Oregon inflated its visitor counts in 1997, the first year the fees were charged, to warrant a larger budget.

Meantime, may question the service's crackdown on visitors.

Last month, Eugene residents Leeanne Siart and George Sexton hiked into the Oregon Dunes National Recreation Area without the required $5 pass for their windshield.

The two say they were videotaped, threatened with arrest and fined $50 by two U.S. Forest Service officers who were waiting at their car.

They plan to contest the fine in what could become the first key test in this region of the notion that the public should pay to play on its own lands.

Officials declined to discuss the pending case. In other states, judges have dropped charges against many fee resisters.

© 2001 Geo. J. Foster Co. (Emphasis added.)