Water reuse: a solution to drought in the Florida wetlands
| West Palm Beach, Fla.
South Florida is one of the wettest regions in the country, but this year it's caught in a drought. A leading indicator of the dryness – Lake Okeechobee – dropped to a record low of 8.8 feet in July. Now just below 10-1/2 feet, it is still five feet shallower than average.
The region has tried to compensate. Its water-management district instituted the toughest usage restrictions in history last spring, allowing lawn irrigation or car washing only during certain narrowly defined times. "Water cops" were deployed to ticket scofflaws who misuse the water.
But it's not enough, experts say. At stake is not only the drinking supply for more than 5 million people, but also the health of the Everglades and agricultural production.
That's why South Florida is turning to another solution: water reuse.
Already, since the mid-1990s, the region has more than doubled water reuse – to some 230 million gallons per day in 2005, according to the South Florida Water Management District. That's 28 percent of the water cycled back through public-treatment systems – but only a small share of the total 3.4 billion gallons a day that gets used, most of it devoted to agriculture or otherwise lost to lawn irrigation or other uses.
One of the most innovative ways to reclaim wastewater is to treat it to the point where it's nearly potable and then to let land – a natural filter – finish the job.
Just 10 minutes inland from the densely developed Atlantic coast, the city of West Palm Beach runs a reclamation project that combines advanced wastewater treatment with habitat restoration. Here, on the edge of Grassy Waters Preserve – 20 square miles of wetlands, which provide most of the drinking water for 130,000 people in the city and surrounding municipalities – the city began augmenting its water supply last November. The city can sprinkle up to 10 million gallons per day of highly treated reclaimed water onto the marshy expanse.
Bordered by residential development, the preserve is a tiny portion of the historic northern Everglades and a habitat for bald eagles, alligators, bobcats and numerous other species. The additional water will enhance biodiversity, according to Patrick Painter, a biologist who manages Grassy Waters.
"Anytime you add water ... it's a dynamic system," says Mr. Painter.
What's more, the nearly potable reclaimed water will lessen West Palm's dependence on Lake Okeechobee, which, situated just west of Grassy Waters, provides 25 percent of the city's annual supply.
Mr. Painter says the reclaimed water is expected to take around two years to filter down through native plants before being pumped to the city's reservoir where it will be processed for drinking. Trickling through the vegetation and soil helps clean the water of remaining trace impurities such as nitrogen and phosphorous.
While West Palm's reclamation project wins praise from community leaders and the local Sierra Club, the municipality says it still injects around 30 million gallons or more per day of less treated sewage 3,000 feet below ground.
"In the future, deep-well injection and ocean outfalls [pipes] for wastewater will be a thing of the past," says Carol Ann Wehle, executive director of the water-management district.
"You'll see reusing that water as a source." Ms. Wehle expects restrictions to continue into next year.
The WateReuse Association, a non-profit water reuse group, estimates that 32 billion gallons per day of municipal sewage were produced in the US in 2006. Of that, they estimate 3.4 billion gallons per day were reused. By 2015 the Association expects the amount of wastewater being reused will surge to 12 billion gallons per day.
One of the greatest continuing challenges in Florida is population growth. The state's population is projected to increase from 18 million current residents to around 30 million by 2030, with the most populated and thirsty counties of South Florida – Miami-Dade, Broward, and Palm Beach – among those expected to see the most growth.
Water reclamation is a positive step, says Drew Martin, cochair of the Sierra Club's Everglades committee. "The problem from our standpoint," he adds, "is there's just not enough of it."
That, however, may come down to money. It took $37.7 million to implement the city's Wetlands-Based Water Reclamation Project, according to Ken Rearden, the city administrator in charge of utilities for West Palm Beach. That figure includes costs for the advanced treatment plant, engineering, and land. Mr. Rearden says it costs $1.85 million per-year more to run the reclamation project than to inject the water underground.
Rearden says the city is moving to study the feasibility of building another advanced wastewater treatment facility, which would double its reclamation capacity by adding another 10 million gallons a day.
"There just isn't enough water to go around if everyone has a straw in the ground," says Painter. "We've got a long way to go before we can make this place sustainable."
