Water Pollution Solution: Build a Marsh

Article excerpt

A few towns across the country are proving that a low-tech, low-cost system of constructed marshes can turn a "disposal problem" into a resource.

ALL THE WATER this planet has ever had and will ever have is now on earth--a fixed commodity that is constantly and naturally recycled. Most of the world is covered by water, but less than one percent of it is available for human use, and unfortunately, pollution from many sources has degraded much of that. The cleansing and recycling of our water resources will be one of the great challenges of the 21st century.

The federal Clean Water Act of 1965 and its 1972 amendments mandated reduction of point-source pollution (pollution generated at a specific site). In meeting these new standards, numerous communities and factories around the world have learned that huge treatment plants are not the only or best solutions. Nature provides its own highly effective water-cleansing system--it's called a marsh. According to a growing number of experts, marshes and wetlands can clean up almost anything we can throw in.

Arcata is a town of 15,000 on the northern California coast where citizens "flush with pride." The town, once known for its redwoods and more recently for the marijuana produced in logged-over forests nearby, has a new export--tangible proof that a constructed wetland system can provide cost-effective and environmentally sound treatment for municipal wastewater.

Back in 1979, Arcata's sewage-treatment plant was failing. Its discharge into Humboldt Bay did not meet the Clean Water Act's wastewater standards, and it was operating with a temporary pollution exemption from the state. Something had to change.

Guided by the fervent belief of Dr. George Allen, a fisheries professor at Humboldt State University, that wastewater is a resource and not a disposal problem, a coalition of academia, local politicians, concerned citizens, city bureaucrats, and environmental groups launched an attack against the conventional wisdom of sewage treatment. The town wanted to opt out of the county's expensive regional treatment plant and install a low-tech, low-cost system of marshes to treat its wastewater.

In what became known as the "Wastewater Wars," the town of Arcata ultimately triumphed over the state bureaucracy and local naysayers. Because the effluent (wastewater) would be released into Humboldt Bay rather than the Pacific Ocean, state law required Arcata to prove not only the system's ability to meet wastewater standards but that it would enhance the Bay. A three-year pilot project demonstrated the marsh system's effectiveness (see "Waste Not Wastewater," American Forests, June 1982).

The city proved enhancement in two ways. The first was George Allen's aquaculture research station, which utilized the effluent to raise anadromous fish. The second was the restoration of wetlands, which created additional wildlife habitat. Arcata opened its full-scale treatment process in 1986 for far less than the proposed $50 million regional treatment facility.

The Arcata Marsh and Wildlife Sanctuary adjoins Humboldt Bay, just three minutes from downtown. A primary treatment plant and oxidation ponds settle out solids and begin the biological breakdown of the sewage with micro-organisms. Effluent then moves through three 2-acre treatment marshes before going through three enhancement marshes in the Arcata Marsh and Wildlife Sanctuary.

Wetlands improve water quality with a mix of physical, chemical, and biological processes. Marsh vegetation obstructs water flow, enhancing sedimentation (settling of solids). The vegetation also provides an environment for algae, fungi, protozoa, and bacteria, the microbes that break down or remove substances from wastewater.

As early as 1970, Dr. George Allen demonstrated the value of effluent from Arcata's treatment ponds. He used it to establish an aquaculture research station to rear juvenile salmon in wastewater-sea-water ponds. …