PORTLAND — The U.S. House has lent support to efforts to restore a Willamette Valley stream degraded over the years by lightly regulated logging, trashy campers and rowdy partiers.

Its vote Thursday would protect a 21-mile stretch of the headwaters of the Molalla River in Clackamas County under the Wild and Scenic Rivers Act. The bill goes to the Senate, where its prospects are uncertain.

A coalition of more than 40 groups, including local governments and environmentalists, hopes the designation would further goals such as attracting families and river recreationists from the Portland metro area and boosting fish runs. The river’s wild spring chinook salmon are thought to be on the brink of extinction, if not over.

The group’s leader says a police crackdown the past two summers has brought new visitors to the river to replace those who used to make riverside camp by running pickups over the vegetation to make a flat space, trample streamside plants and, in the absence of campground bathrooms, leave behind feces,

“Now, it’s a family of four instead of four guys in a 4x4,” said Mike Moody, president of the Molalla River Alliance.

The Molalla rises in the Cascade Range and runs about 50 miles to its confluence with the Willamette River south of Portland. In its lower reach, it provides water for the cities of Molalla and Canby.

An analysis by the environmental group American Rivers said forests along the Molalla were logged so heavily in the mid-20th century that the river would turn red with sediment during Oregon’s frequent rains. Late-century regulation, it said, means the river runs red only in the heaviest of storms, three to five times a year.

The federal government owns most of the land affected by the designation. Under the wild and scenic designation, the Bureau of Land Management would to draw up a management plan to protect river values. Moody said the agency is already working on a camping plan.

He and the bill’s sponsor, U.S. Rep. Kurt Schrader, said there was no opposition from timber owners such as Weyerhaeuser. Schrader said the local interests had “crafted this bill to reflect the diversity of their community.”

On the House floor, Republicans objected.

Rep. Doc Hastings of Washington state said the government should provide logging land elsewhere to replace 411 acres — less than a square mile — that had historically been set aside to generate revenue for local governments.

Schrader and others said there are no plans to log the land, and none are likely.

The tally was 292-133. Forty Republicans, including Oregon’s Greg Walden, joined 252 Democrats in the majority. No Democrats voted against it.

The Senate isn’t expected to consider the Molalla until next year. Backers said they worry that Republican Sen. Tom Coburn of Oklahoma could block the measure, as he has done with similar measures. One involved Mount Hood wilderness. But spokesman Don Tatro said Coburn hasn’t seen a Molalla bill yet.