CLEWISTON — Standing in a sugar-cane field, Mitch Murphy watches a backhoe scoop up rich black muck from a ditch and deposit it on the bank, where it will be reused.

About 30 miles east, Tracey Piccone stands on a bridge near the Loxahatchee National Wildlife Refuge, marveling as 24,000 gallons of water a second rush under her feet into one of the largest man-made wetlands in the world.

Murphy and Piccone are foot soldiers in the battle to stop phosphorus from destroying the Everglades, and even as a firestorm rages over amendments to the law mandating cleanup of the fabled River of Grass, they remain proud of their court-ordered accomplishments. And for good reason: They're paying off.

For Murphy, it's tedious work, but the maintenance supervisor with the U.S. Sugar Corp. is doing his part to keep even more pollution out of the Everglades and keep his paycheck coming.

"I'm in farming, but I'm also an avid hunter and fisherman, and I want to clean up the water as much as I want to protect my livelihood," the lifelong Clewiston resident said.

Piccone, an environmental engineer with the South Florida Water Management District, is equally proud to know that the wetlands -- or stormwater-treatment areas -- like the one constructed near the refuge are absorbing more harmful phosphorus than expected from waters draining from farms, urban lawns and Lake Okeechobee.

"That's why all the people throwing stones at us is so hurtful," the fifth-generation Floridian said. "They know what we've done."

During the past decade, new farming practices and wetlands carved mostly from former farmland have reduced the amount of phosphorus entering the Everglades by 1,430 tons. Assuming that most commercial fertilizer contains 10 percent phosphorus, that's equivalent to the phosphorus in 1.5 million 20-pound bags of fertilizer from a lawn and garden center.

"The progress is dramatic. It's significant. It ought to be celebrated," said Gary Goforth, the water district's chief consulting engineer on Everglades restoration.

But it's not dramatic enough for environmentalists. They were counting on even better performance. And they're still livid over a sugar industry-backed bill that popped up in the middle of this year's regular legislative session to amend key provisions of the 1994 Everglades Forever Act.

They insist the changes push pollution-reduction deadlines back 10 years, giving sugar a free pass and jeopardizing the $8 billion federal-state plan to re-plumb the Everglades in the next 30 years. A federal judge and several members of Congress have the same concerns.

"I think what we've accomplished so far is a very good start, and everybody can be proud of where we've gotten," said Charles Lee, a lobbyist with Audubon of Florida. "What is shameful is that the legislation essentially freezes further progress."

Unnatural Cattail Growth

At issue is phosphorus, a nutrient found naturally in soil and rain and a key component of fertilizer. About a decade ago, about 270 tons of phosphorus was washing into the Everglades from runoff every year, fueling an unnatural growth of cattails that choked off saw grass and altered the unique ecosystem. The consequence: Habitats for alligators, wading birds and other indigenous species were rapidly disappearing.

To halt the destruction, the federal government sued Florida in 1988, accusing the state of failing to enforce water-quality standards on federal lands. After four years of litigation, the parties settled by agreeing to find ways to reduce phosphorus flows into the Everglades.

How remained a source of contention -- and more litigation -- until the Legislature passed the Everglades Forever Act in 1994.

That law authorized the district to convert more than 40,000 acres of land bordering the northern Everglades into six phosphorus-absorbing wetlands.

It also required farmers in the 505,000-acre Everglades agricultural area south of Lake Okeechobee, the majority of which is devoted to sugar cane, to adopt new farming techniques that would reduce the amount of phosphorus leaving their fields by 25 percent every year.

In the past decade, farmers have consistently surpassed and often doubled that requirement, cutting the amount of phosphorus that would have found its way into the Everglades by 1,100 tons.

The result has been considerable improvements in water quality. Before 1991, water leaving the agricultural area contained, on average, 173 parts of phosphorus per 1 billion parts of water. Last year, that average fell to 77 ppb.

Trapping Phosphorus

Farmers have accomplished those reductions by adopting practices that trap phosphorus-rich soil on the farm. Among the most successful techniques is the one Murphy supervises. Instead of allowing soil sediments that wash into ditches to be carried into the vast system of flood-control canals protecting South Florida, Murphy's crews regularly scoop the dirt out and plow it back into their fields.

Farmers also have modified pumping practices to release water into drainage canals less often and more slowly. For example, instead of turning on pumps whenever it rains, they wait until canal water reaches a minimum height. That allows phosphorus to settle, rather than be stirred up and swept away with the water.

Lest farmers forget the importance of that measure, signs posted at U.S. Sugar's pump houses carry this warning: "Remember: Reduce Pumping: Save the Everglades. Reduce Pumping: Save Your Jobs."

The water district takes the credit for filtering an additional 330 tons of phosphorus from runoff in the past decade. Today, about half of the runoff leaving the Everglades agricultural area is diverted into four man-made wetland areas.

Two more of these stormwater-treatment areas, including the largest, are still under construction. Scheduled to come on line before next year, they will double the acreage devoted to the cleansing ponds, eventually treating all water leaving the Everglades agriculture area.

'Living, Breathing Systems'

Much to the surprise -- and delight -- of water managers, the man-made wetlands have performed better than expected. As an interim goal, they were designed to discharge water into the Everglades at no more than 50 ppb phosphorus, yet average outflows have been between 20 ppb and 40 ppb.

"We were losing sleep over that [goal]," Goforth said. "Nobody in the world has done systems this large. These are living, breathing systems with natural fluctuations. You can't just flip a switch and have it work a certain way."

Oddly enough, the wetlands rely on cattails to reverse the trend. Essentially designed to replicate the areas of the Everglades affected by high concentrations of phosphorus, the wetlands produce thickets of cattails that consume the nutrient, preventing its release farther downstream. The wetlands also rely on submerged and floating aquatic vegetation to perform the same phosphorus-absorbing function.

The big trick for district scientists and engineers is finding which mix of plants, operating techniques, structural changes and farming practices will consume the most phosphorus and reduce water discharges to 10 ppb.

Legislative Controversy

Many scientists think limiting phosphorus to that level will protect the natural flora and fauna of the fragile ecosystem. The Everglades Forever Act required the district to meet that number, or one set by a state regulatory commission, by the last day of 2006.

And therein lies the controversy over the legislation, which supporters and critics interpret in vastly different ways.

After a number of permutations, the final version signed into law by Gov. Jeb Bush requires the water district to make the technical changes necessary to improve the performance of the water-treatment areas and new farming practices by the end of 2006.

However, it does not require them to meet the 10 ppb phosphorus criterion by then -- but rather a standard that recognizes progress toward that goal. To environmentalists and other critics, that's an unconscionable delay.

"It's like saying a bank robber who decides to quit robbing banks is successful if he only robs half as many banks as before," said Ronald Jones, a microbiologist and a witness in the lawsuit.

State officials counter that the amended law accelerates the cleanup effort while recognizing the limitations of evolving science and technology.

For now, environmentalists are counting on Congress or U.S District Judge William Hoeveler, the judge monitoring the settlement agreement, to ensure Everglades restoration remains on track.

In the meantime, the harmful cattail incursion continues, supplanting what environmentalists say is up to 9 acres of Everglades a day. Goforth says the rate may be only half that, but to Audubon's Lee, the difference hardly matters.

"The bottom line is a huge piece is lost every day, and the Everglades cannot survive if that continues," he said.