Phoenix Uses Cleaning Power Of Wetlands to Scrub Sewage
As the burnt-yellow sun rose above the Estrella Mountains, the marshy landscape sprang to life as if it were choreographed.Skip to next paragraph
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A blue heron swooped in from the backlighted horizon on a fishing expedition. Hundreds of yellow-headed blackbirds soared from the reeds, littering the blue skies with dark specks of color. The cool air had come alive with chatter.
"Ah, sunrise at Tres Rios," says Roland Wass, keeper of this habitat on the outskirts of metropolitan Phoenix. "And it's looking just great."
Looks are beside the point for Tres Rios, a man-made experimental wetlands on 12 acres at the 91st Avenue wastewater treatment plant, a facility run by Phoenix to handle its sewage and that of four other municipalities.
Officials in this Southwestern desert city are hoping that the project ultimately will enable them to comply with federal mandates governing the quality of water pumped out of the plant when the treatment process is completed.
The final wetlands system, officials say, will allow them to "polish" all the plant's effluent to the quality desired by regulators at a much lower cost - and will be environmentally friendly as well.
The ripple effects could be felt nationwide. "We've already shown that it works," says deputy city manager David Garcia, who oversees the project. "We think what we're doing at Tres Rios can be used almost every place" in the US.
That's assuming a community is willing to set aside enough land to build a wetlands. The system requires up to 75 acres per 20,000 people - acreage that is easier to acquire in the wide-open West than in the East. Then there are the mosquitoes and foul smells that can accompany constructed wetlands.
Moreover, some experts say, new wetlands may become home to endangered species, a situation that would trigger more federal scrutiny and raise city concerns about loss of local control.
Still, wetlands experts look to Tres Rios with hope, reasoning that it could pave the way for other communities - small and large - to use this low-tech approach to comply with government mandates.
"It kind of disarms people when you say a place like Phoenix is doing it," says Bob Gearheart of Humboldt State University in Arcata, Calif, a technical adviser for the project. "They say, 'Wow, they're doing it in the desert?' It really enlarges the vision for its application."
Phoenix jumped into the wetlands business in the early 1990s, when it learned that the price tag to upgrade its wastewater treatment plant to meet new water-quality standards would be more than $625 million. The projection sent officials scrambling for another way.
By 1995, the city had received the go-ahead from state and federal officials and began to build Tres Rios. First, officials turned farm land into a three-pond habitat by bringing in trees and greenery, including two types of bulrush, a cattail-looking plant normally found in wetlands. Then they let the waters flow - and crossed their fingers.
THEY found that the ponds do a good job of extracting contaminants such as nitrates and mercury as the wastewater steadily flows through the different water levels and various vegetation. The finished water then empties into a normally dry river bed. The finished product meets standards and, in some cases, exceeds them, officials say.
City officials now seek to raise more than $80 million to expand the project to 800 acres. A wetland that size would be able to handle all effluent generated by the sewage treatment plant, they say. So far, Phoenix has obtained $2 million and is pushing for the project to be included in future federal appropriations.
"This has all the right buzz words attached to it," says Norris Nordvold, the city's lobbyist. "It saves money, is environmentally friendly - it has it all."