CORVALLIS, Ore. (AP) -- It's a little before 9 on a weekday morning, and a steady stream of commuter traffic is pouring into downtown Corvallis on Highway 20.
Just a few yards from this pulsing urban artery, Travis Williams slides a canoe into the quiet waters of the Willamette River and slips into a different reality, where eagles still nest in cottonwood trees, otters still patrol the currents and salmon still make their way upstream to spawn.
``You never know what you'll see,'' says Williams, executive director of Willamette Riverkeeper, an environmental watchdog group. ``This is cool.''
As the boat pulls away from the bank, the sights and sounds of human activity quickly recede. But on this river, they're never far away.
Winding 187 miles from Eugene to Portland, the Willamette flows right through the agro-industrial heart of Oregon, harboring a wealth of aquatic life while rubbing shoulders with the largest population centers and richest farmland in the state.
Once so polluted it literally choked fish to death, the river made an astounding comeback in the 1960s and '70s to become a national poster child for restoration: The successful cleanup effort was featured on the cover of National Geographic.
Unfortunately, however, the story didn't end there.
Despite continued progress in many areas, persistent toxics such as DDT, PCBs and dioxin still linger in these waters decades after they were banned or sharply restricted. Today, a new generation of chemicals -- from flame retardants to weed killers, antidepressants to birth-control medications -- is finding its way into the river, posing a new set of challenges that scientists are just beginning to understand.
There are other challenges as well.
A growing chorus is calling for changes in the way river flows are managed. Generations of Oregonians have diked, dredged, channeled and dammed the Willamette in an effort to tame its wild waters. In recent years, however, researchers have documented a host of environmental benefits linked to seasonal flooding, side-channel flows and slackwater alcoves, from supporting threatened fish populations to cooling water temperatures to propagating willows and cottonwoods.
A number of projects are under way to restore floodplain connectivity, and the U.S. Army Corps of Engineers is adjusting water releases from its network of 13 Willamette Basin dams to more closely mimic natural flow regimes. Some landowners are embracing this new approach, but others balk at the notion. Giving ground to the river, they argue, only invites erosion, crop losses and catastrophic flooding.
The Willamette today is a work in progress - a far cleaner waterway than it once was, but not yet the robust picture of health many Oregonians would like it to be.
``It would be false to say it is healthy,'' said David Primozich of the Willamette Partnership, which is developing a system of ecosystem services credits aimed at lowering water temperatures in the river and its tributaries. ``The system is cleaner than it was 30 years ago, but there's a lot more to ecological health than water quality.''
The 13th-largest river in the United States by volume, the Willamette is a vital resource that provides water for drinking, irrigation, industry, hydropower, recreation, fish and wildlife.
But that resource is under intense pressure. About 2.4 million people _ 70 percent of all Oregonians _ live within the Willamette watershed, and that number is projected to increase to 4 million by midcentury.
In 2008, the state Department of Environmental Quality launched the Oregon Toxics Monitoring Program, a new effort to keep tabs on pollution in the state's waterways, starting with the Willamette. It was the first systematic assessment of toxic pollution in the river since the early 1990s.
DEQ researchers took water samples from 20 sites on the mainstem Willamette and its major tributaries - once in September, when river levels are low, and again in December, when flows are higher. They also took tissue samples at 12 sites from smallmouth bass and northern pikeminnow, resident fish species that spend their whole life cycles in the river rather than migrating from the ocean.
Program coordinator Jim Coyle said he was encouraged by the first year's results _ for the most part.
``I think the Willamette River, from a toxics perspective, has improved dramatically in the last 15 years,'' Coyle said. ``That's not to say there's no problems.''
The good news: In general, water quality throughout the river was pretty high. At numerous locations, lead and copper levels were above thresholds considered healthy for aquatic life, but no glaring threats to human health were found.
That doesn't mean you should drink straight from the Willamette, of course, but the water's fine for swimming, boating and water-skiing. (One exception: Heavy rains still can overload some municipal wastewater systems, sending untreated sewage into the river after a storm.)
The bad news: Some pretty nasty toxins still show up in resident fish - and not just in the historically polluted reaches of the Portland Harbor. At all 12 collection sites, carcinogenic polychlorinated biphenyls - PCBs - were found at or near federal danger levels for people who eat fish regularly.
Other toxics found in tissue samples include dioxin, mercury and DDT. State health advisories currently are in effect for fish from four stretches of the Willamette, and higher fish consumption standards recently adopted by the Oregon Environmental Quality Commission could result in even more warnings.
All of these substances are classified as ``persistent bioaccumulative pollutants'' because they build up in the fatty tissues of fish and other animals and remain in the food chain.
``It would be much worse if we hadn't banned these chemicals, but they're so persistent that they're still in the system today,'' Coyle said.
``I think we're on a glide path, and the concentrations have come down substantially since the '70s. But I think we're going to see the legacy of these chemicals for some time to come.''
But even more troubling, on some levels, is the rising tide of chemicals entering the Willamette and other waterways whose effects are poorly understood, at best.
DEQ testing found polybrominated diphenyl ethers in fish tissues from all sampling sites on the river. PBDEs, which are widely used as flame retardants in everything from electronics to textiles, have been shown to lower human fertility levels and may cause problems with brain development.
It's not clear whether the presence of these chemicals in Willamette River fish poses a hazard to human health because, as the DEQ report notes, ``no federal or state screening levels are available for comparison.'' The same is true for many currently used pesticides, including some found in the river.
Pharmaceuticals and personal care products also are finding their way into the Willamette, raising concerns about their impact on aquatic life. Analysis of water samples found antidepressants, anticonvulsants and antibiotics that entered the river after being either discarded or excreted by humans. Add to that list sunscreens, insect repellants, cosmetics and other commonly used consumer products.
The effects of these compounds on environmental and human health are still being evaluated, the Oregon Toxics Monitoring Program cautioned in its initial report.
``In essence, we're conducting experiments in the environment,'' Coyle said. ``The drive to make all these products is strong, but the funding to test for impacts is not always available.''
Other threats to the Willamette's water quality are less sinister but more pervasive.
Another recent DEQ report, the Willamette Basin Rivers and Streams Assessment, found that one of the most critical factors affecting the health of the Willamette and its tributaries is land use. Urbanization, farming and forestry all contribute to rising water temperatures that can harm salmon and other aquatic creatures, largely by removing streamside vegetation.
``What we're starting to understand is that water quality begins at the rooftop,'' said Dennis Ades, the water quality program manager for DEQ.
``A lot of the problems we're seeing are related to the land use decisions that we've made.''
Our growing cities are a prime example. As the valley's population expands, so does the amount of impervious surface area _ from rooftops to parking lots _ that channels the region's plentiful rainfall into drainage ditches, storm drains and, ultimately, the river.
``Basically, it's very simple. If you protect streams and you protect riparian areas, you protect the watershed,'' Ades said. ``If you build residential developments right up the edge of the stream, you've got problems.''
In any assessment of where the Willamette River is going, it's worth looking back at where the river has been.
Throughout the 1800s, settlers flocked to the Willamette Valley, farming the deep alluvial soils and using the river as a transportation corridor.
But the river also was a convenient conduit for municipal and industrial waste. By the mid-20th century, it was an open sewer.
Writing in the Oregon Historical Quarterly in 2006, biologist Glen D. Carter recalled what conditions were like 50 years earlier when he joined the Oregon State Sanitary Authority, the precursor to today's Department of Environmental Quality:
``By the time I was hired in 1956, fish kills were common in the river, massive rafts of decaying algae floated downstream, and a thick layer of bacterial slime covered much of the river bottom and shoreline. Rotting vegetation, bacterial slime and countless dead fish produced highly unpleasant sights and odors. Large deposits of raw sewage sludge accumulated around sewage outfalls.''
Many Oregonians, appalled at what had become of the state's most iconic river, began to clamor for change. Television newsman Tom McCall galvanized public opinion with his 1962 documentary on the river's plight, ``Pollution in Paradise.'' Two years later, as governor, McCall initiated a major cleanup effort.
The transformation was so remarkable that it made national news.
In June 1972, the river was featured on the cover of National Geographic. Under the headline ``A River Restored,'' the magazine touted the Willamette's rebound from industrial cesspool to environmental emblem.
Even today, the Willamette remains far cleaner than many of America's other major rivers. Oregonians who once shied away from its shores are coming back to swim, boat and fish in its cool green waters.
But people like Willamette Riverkeeper's Travis Williams see a danger in complacency.
``People said, Wow, we've got this great environmental success story.' And that was true then,'' Williams said. ``But in the last 40 years, we've learned a lot about river systems and what goes into them.''
It's important, he believes, to keep working to restore the Willamette to a more natural state - and to keep up our guard against the emerging threats to the river's health. And these goals will only become more crucial as the valley's population swells, putting still more pressure on the river that gives it life.
``I think we owe it to ourselves,'' Williams said.
``We live so close to it. Wouldn't you really want it to be as good as it could be and make it healthy for all of us? I mean, I think it's as simple as that.''