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From Effluence to Affluence
A California town is filtering its sewage through marshes, thereby improving the wastewater’s quality and restoring wildlife habitat. Now the idea is catching on.


A river otter rises out of the water, its body a silver arc, reflecting the glow of the setting sun. I slow from a jog to a walk and peer through the cattails, hoping for another glimpse. But the otter has vanished beneath the thick carpet of greenery that floats on the pond surface. The only visible creatures are coots and mallards, their heads painted with bright flecks of duckweed.

A bit farther along, I round a bend in the trail and enter into the shade of tall willows. My neck prickles. I have the feeling that someone is watching me, though I haven’t seen another human in the past quarter-mile. I turn and lock eyes with a barn owl, perched six feet away on a willow branch, waiting for the last light to fade before he sets off to hunt.

The Arcata Marsh and Wildlife Refuge lies at the edge of Humboldt Bay on California’s northern coast, a few blocks from the center of my adopted hometown, Arcata, population 17,000. It’s a rich habitat for creatures of all kinds, from aquatic worms to frogs to shorebirds, grebes, ducks, and pere-grine falcons. And sewage runs through it.

The waters that feed this lush wetlands flow out of Arcata’s municipal treatment plant, which uses conventional technologies, including settling tanks and oxidation ponds, to treat the town’s sewage. But unlike most cities, Arcata has also harnessed marsh plants and microbes to help clean its wastewater. Several treatment marshes, thick with cattails and bulrushes, filter wastewater that has already been through the conventional process before it passes into the wildlife refuge and then into Humboldt Bay. The creation of this system has improved the quality of the effluent released to the bay while restoring 154 acres of habitat vital to migratory birds and an array of other native species. The marsh is also a sanctuary for hikers, picnickers, and birders—though many of them don’t realize this bucolic spot has anything to do with sewage.

In the 1970s, when a few Arcata residents came up with a plan to build a wetlands as an adjunct to the city’s sewage treatment plant, the idea was considered radical. But in ecological terms, the concept is old hat; marshes have always been natural water filtration systems. Flowing water slows as it passes through a sieve of cattails and other aquatic plants, allowing sediments to settle to the bottom. Meanwhile, the plants absorb nutrients from the water around them. Underwater root systems and the open waters of marsh ponds host a complex community of algae, bacteria, and fungi, all of which work to break down organic waste.

Even the most high-tech sewage treatment facility is just an artificial habitat for the same microbes that break down pollutants in wetlands. Conventional treatment systems use a lot of energy to pump oxygen into wastewater. Oxygen balance is an essential factor because human waste affects aquatic communities like a jolt of fertilizer. If too much waste hits the water at once, populations of algae and bacteria explode, then deplete all the available dissolved oxygen. When that happens, lakes and ponds can die, suffocating on an excess of nutrients.

In the 1960s this kind of disaster threatened waters across the United States. Fish in the Great Lakes floated belly-up by the thousands. The crisis led to the 1972 passage of the federal Clean Water Act, the first U.S. law aimed at protecting aquatic ecosystems.

Soon after, California officials closed the  Humboldt Bay oyster fishery, the basis of a thriving industry, because of fecal contamination. “The *@#! was hitting the proverbial fan,” remembers Robert Rasmussen, a botanist and environmental consultant whose firm was called on to write an environmental impact report on the state’s proposed solution to the problem.

There was only one acceptable answer, claimed the head of the Regional Water Quality Control Board. All the waste from Arcata and Eureka, a neighboring city seven miles south on Humboldt Bay, would have to be piped across the bay floor to a single, high-tech facility for treatment, then released into the open Pacific.

In the late 1970s, a time of national energy crisis, the proposed regional sewage system promised to become the biggest energy consumer in the county. The report from Rasmussen’s firm criticized the state plan, pointing out that dumping treated wastewater in the ocean rather than the bay would not eliminate the problem. It argued that Humboldt Bay itself, long subject to heavy loads of natural runoff from the surrounding hills, was better adapted to handling high nutrient loads than the Pacific’s shallow coastal waters.

A few Arcata activists opposed the state plan, but their cause appeared hopeless. A small cadre of young, progressive newcomers, who in 1974 overcame the vehement opposition of the town’s traditionalists to win election to Arcata’s city council, spearheaded the fight. During several years of struggle against California’s entrenched water quality bureaucracy, they assembled a motley array of allies, bringing together people who had never before found a common cause. These included members of a local Taxpayer’s League; the Redwood Region Audubon chapter; engineering, wildlife, and economics professors at Humboldt State University; fishermen and dockworkers who drew their livelihood from the bay; even the owner of the local 7 Up bottling plant. The coalition surprised everyone by winning—and they won by inventing the idea of the municipal wastewater wetlands, a way to clean polluted water, save money and power, and create badly needed wildlife habitat.


Since the mid-1800s, when the gold rush brought floods of settlers to the state, California has lost more than 90 percent of its natural wetlands. Birds now flock to any bit of marsh they can find. Over the course of a typical year, more than 250 species are seen at Arcata’s marshes. “I was 100 percent confident that the marsh would work, even before we did a pilot study,” says Robert Gearheart, who came to Arcata in 1975 as a newly hired environmental engineering professor at Humboldt State University. “The problem was convincing the regulatory people. We gave up trying to convince the engineers.” In the early 1980s Gearheart and his students built small-scale experimental marshes to prove the technique could work to further clean wastewater that had been pretreated using low-tech, conventional processes. At last the state dropped its insistence on a high-tech regional system. Ultimately, Gearheart and his students would design the series of successful treatment and habitat wetlands that grace Arcata’s waterfront.

Back in the 1970s and 1980s they were fighting a powerful trend in the engineering world. The Clean Water Act provided funding for sewage treatment facilities throughout the United States. Under the law, engineers were paid a percentage of construction costs. With no incentive to consider low-tech, economical alternatives, they built the most grandiose systems possible. The virtue of centralized, energy-intensive treatment systems became unquestioned engineering dogma. “To be honest,” says Gearheart, “my profession had got things going in the wrong direction. They saw the Clean Water Act strictly as a wastewater treatment gravy train.”

Building Arcata’s marshes changed the course of Gearheart’s engineering career. He has consulted for the Peace Corps and the U.S. Agency for International Development on appropriate technologies throughout the Third World, and he and his students have helped to create sewage treatment wetlands in such far-flung spots as Laos and Palau. After the project in Arcata took off, Gearheart realized the argument for these inexpensive, eco-friendly techniques is just as strong here in the United States as it is in developing nations.

A number of communities in the United States and Canada have adopted the wetland wastewater treatment strategy, including the cities of Martinez and Hayward in California’s San Francisco Bay area; Tucson and Phoenix, in Arizona; and Orlando, Florida. One of the main limitations, however, is that marsh restoration projects like Arcata’s require empty land—a rare commodity in most big cities.

Still, ecologists and engineers continue to grow the idea of marshes for clean water, finding creative new variations on the theme. John Todd, president of the nonprofit Ocean Arks International; founder of John Todd Ecological Design Inc., an environmental engineering firm; and a research professor at the University of Vermont, has found a way to bring wetland water treatment to cities without taking up a single acre of land.

His strategy is the Restorer, a wetlands planted on a raft and set afloat on polluted waters. Hanging off the raft’s bottom are a series of sheets made of an artificial medium that hosts bacteria, fungi, and algae. 

“Arcata set the esthetic example for the rest of the world,” says Todd. “Wastewater treatment doesn’t have to be ugly.” In the Chinese city of Fuzhou, Todd and his colleagues have used Restorers to beautify a canal blighted by continuous inflows of raw sewage. A series of Restorer rafts now extend along the full length of the canal and bloom with native Chinese wetlands plants.

The canal runs through a residential neighborhood, and the local people welcome the floating wetlands, says Todd. “The terrible stink has gone away. One old guy in his eighties told us that he’s seeing birds and butterflies he’d never seen in that part of town before. We now have thousands of carp living in the canal, which is great public relations, because the people there like to fish.”

Both Todd and Gearheart see constructed wetlands as one of the most promising answers to the problem of nonpoint source pollution—runoff from streets and farm fields, which is often badly contaminated but in most places goes untreated. Beyond its well-known marshes, Arcata has created a few small wetlands, scattered at strategic spots around town, which filter storm runoff that rushes into the bay during the drenching rains of winter. “Bays and estuaries are still heavily impacted by nonpoint source pollution,” says Gearheart. “The original Clean Water Act left these important issues for last.” 

William Mitsch, a professor of natural resources and environmental science at Ohio State University, hopes to use wetlands restoration to remedy nonpoint source pollution on a grand scale. A decade ago Mitsch, who earlier in his career conducted groundbreaking research on wetlands restoration, was asked to chair a committee that would advise the federal government on ways to revive the “dead zone” off the mouth of the Mississippi River in the Gulf of Mexico. The problem is at its worst in the summer, when up to 7,700 square miles of the Gulf’s waters are too depleted of oxygen to support marine life.

A major culprit is nitrates from artificial nitrogen fertilizers used on corn and other  crops throughout the vast Mississippi River basin (see “A Mighty Challenge,” May-June 2006). “We looked at just about every possible strategy, and kept coming back to the fact that the most palatable way would be to re-wetland the Midwest,” says Mitsch. “If we can use 1 to 5 percent of the landscape as wetlands, that’s a great deal, because it will allow the other 95 percent to stay productive.”

Wetlands excel at cleaning up nitrates. Not only do plants and microbes in the water absorb the nutrients, but the dark, anoxic muck of marsh bottoms hosts denitrifying bacteria that transform nitrates into nitrogen gas, which is released to the atmosphere rather than polluting waters downstream. Small marshes restored in the right places—where drainage tiles release farm runoff into creeks and rivers, for instance—could make a world of difference.

In 2001 Congress received a report, based in part on the work of Mitsch’s committee, recommending that 5 million acres of wetlands be restored throughout the Mississippi River basin. “That sounds like a gigantic number,” says Mitsch, “but don’t forget, the basin comprises 40 percent of the U.S. It’s a very big area.”

So far there’s been no organized federal action on the proposal. Mitsch ascribes this to bureaucratic inertia in the responsible agencies, which include the U.S. Department of Agriculture, the Army Corps of Engineers, and the Environmental Protection Agency. “Now more than ever,” he says, “we need to restore wetlands in the Mississippi-Ohio-Missouri River basin.”

Environmental groups like the Wisconsin-based Sand County Foundation, as well as regulators in some midwestern states, have taken up the cause. In Iowa agriculture officials and many farmers recognize that if they don’t stop dumping tons of excess nitrogen into waterways, eventually the EPA will force them to stop—by means that may be far more difficult and costly than wetlands restoration. “They’re sold on the idea that a small percentage of the landscape, converted to strategically placed wetlands, can save farmers from going out of business,” says Mitsch. “Iowa was just sopping with nitrates, and they’ve done a 180 degree turnaround.”

Like the pioneer farmers who settled along the banks of the Mississippi, the gold miners and adventurers who founded Arcata believed marshes were wastelands that served only to breed disease. They saw draining wetlands as righteous work, part of the march of progress. Today it’s clear that the welfare of humans, as well as wildlife, is tied to the wetlands’ rebirth. Mitsch continues to urge the federal government to take action, but he believes the most effective strategy may be for people to take resurrection into their own hands and start creating new marshes one neighborhood, one town, one state at a time.
People from around the world continue to come to Arcata to study its marshes, the wastewater wetlands built by rebellious citizens rather than government agencies. When I go there to jog or birdwatch, I sometimes meet knots of curious visitors from Italy or the Caribbean. They come with the intention of learning about sewage treatment but always end up enthralled with the wildlife. There is a spot where these groups usually pause—just across from the city’s sewage outflow pipe, where great egrets like to hunt. When a big bird captures a fish, you can watch the bulge slide down its slender neck as the predator swallows. Then, with the lumbering grace that is the hallmark of tall wetlands birds, the bright white egret will launch from the mudflat into the sky.

Sharon Levy writes about science and nature from Arcata, California.

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