A plan to pump partially treated water deep underground for a key Everglades restoration test has been scuttled. The South Florida Water Management District has backed away from that idea out of fear that it could jeopardize public support for a larger plan to bank voluminous amounts of surface water underground.

The district had wanted to send only partially treated water - which could still contain harmful microbes and pathogens - into 10 storage wells, one in West Palm Beach and nine on the drawing board. But when state legislators tried to make that practice legal in Florida last spring, environmentalists protested that it could contaminate underground sources of drinking water. That controversy killed the proposed bill and conjured up public perception that the state wanted to poison Florida's drinking water aquifers.

Realizing that sentiment would hurt their own plan, district officials said they will now send fully treated water - meeting all existing clean water standards - into the nine test wells they intend to build within three to four years. That influx of water would test a proposed "aquifer storage and recovery" program. They also abandoned plans to funnel partially treated water into the West Palm Beach well. District board member Patrick Gleason said, "We're trying to basically improve the image" of aquifer storage and recovery.

Before changing their minds, water managers were going to seek a variance from state and federal water regulations to pump the wells with water purged of major toxins but not bacteria and other microbes.

The nine test wells, which would be some 1,000 feet below the ground, are a preliminary step that could lead to the construction of 333 storage wells, a huge component of the Everglades restoration effort. That suite of wells would store up to 1.7 billion gallons of water per day in rock cavities of a geological formation called the Floridan aquifer. During the wet season, storm water would be rerouted down the wells so it can be tapped for later use.

Water district Executive Director Henry Dean said he would start looking for a backup plan for the wells. Environmental groups have argued that a second storage option should be found because it is unclear the system of wells can work on the grandiose scale being proposed. "Why would you put all your eggs in one basket?" said Jonathan Ullman, a Sierra Club representative.

"The public has said, `We don't want our water tampered with,'" said Suzie Ruhl, president and founder of the Legal Environmental Assistance Foundation in Tallahassee.

Shannon Estenoz, Everglades representative for the World Wildlife Fund, said, "I think it's going to go a long way to eventually building public support for the technology."

The well system is so integral to the current ecosystem recovery plan that if it dies, the Everglades restoration could die with it, Gleason said. Dean put it a little less ominously: If the wells were prematurely ruled out, he said, "the restoration becomes something far less than what Congress and the Legislature approved."

The storage plan has been in need of damage control since the Florida Legislature sought to waive standards for coliform bacteria, which can be an indicator of human or animal feces in water.

The water district, state Department of Environmental Protection and the Governor's Office all endorsed the legislation. Government officials said it could trim $200 million to $400 million of the restoration's price tag by eliminating unnecessary water treatment. They said they had scientific proof the bacteria likely would die off in the partially salty, sunless environ. Even if the water became contaminated, it would be treated and sanitized after it was pumped to the surface again, they said.

But the legislation was attacked by LEAF, Audubon of Florida and other environmental organizations angered at the attempt to bypass state and federal rules protecting drinking water sources. After the bill's defeat, the water district sought the variance. The district embarked on a campaign to garner support for its storage wells research from state officials, local governments and environmental leaders. It won some endorsements but also met some stiff resistance.

Dean said he could not ignore what he called "a tremendous erosion" of credibility for the wells before technical questions about their potential restoration role could be answered by research. So the district is going to treat the water to assure it is drinking-water clean, possibly by using ultraviolet light to kill off microbes, Dean said.

"It was always safe in our opinion" to go with partially treated water, Dean said. "But this makes it shotgun-sure safe."

The plan now is to send fully treated water into the nine test wells.

The Everglades restoration project has been a big public relations test.