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Volunteers wore surgical gloves, many afraid to touch the water, as they picked through tangles of mangrove along a lagoon at the edge of Puerto Rico's capital.

They hauled out old tires by the dozen, plastic bottles by the hundreds. They found discarded fishing nets, an old toilet and sink and bags of medical waste that appeared to contain plasma.

"The amount of garbage that has accumulated here in the last 20 years is unbelievable," said Jose Aponte, who helped coordinate the cleanup through a Puerto Rican nonprofit whose name translates as Fish, Beach and Environment.

More than 12,600 pounds (5,700 kilograms) of trash was pulled out of the San Juan Bay Estuary in just a few hours that recent weekend morning, evidence of the enormous scale of the problem, but perhaps also a sign that things might improve. A plan to rescue this urban wetland, which is still a vital habitat and prime tarpon fishing ground despite the pollution, is a priority for the administration of Gov. Alejandro Garcia Padilla, in part to bring more tourists and needed revenue to the gritty capital of the U.S. island territory.

Cleaning the estuary would first mean excavating a solid mass of accumulated garbage that blocks the entrance of the Martin Pena Channel and cuts off the ocean's natural flow, choking the life out of much of the estuary. The $600 million project would take nearly four years, but officials believe it would transform a network of lagoons and streams.

"We expect it to become a Caribbean fisheries hotspot," said Lyvia Rodriguez, executive director of the public corporation the government created to help undertake the project.

The state-owned water and sewer company has pledged $120 million for the effort, and Rodriguez said officials are working to find the remaining money, a daunting prospect with the island entering its eighth year of recession. Puerto Rico's government has not indicated how much if any it would contribute in total.

As the corporation continues searching for funds, nonprofit groups have organized their own cleanups targeting certain areas of the estuary, which is surrounded by a maze of dark-green mangroves that offer shelter and shade to dozens of bird species. Across the open waters, pelicans swoop down for prey and people still catch fish and crab despite health warnings.

Mario Nunez, who grew up next to the Martin Pena Channel, said in the 1970s he and his neighbors would cross the stretch of water by boat to go shopping, paying around 10 cents.

"Now we can cross from one side to the other ... We walk across on top of garbage," said the community leader. "The environmental deterioration has been incredible."

So much trash has accumulated that channel sections once 400 feet (122 meters) wide have now shrunk to a mere three feet (1 meter).

The San Juan Bay Estuary sprawls across eight municipalities and includes the channel, five lagoons and the picturesque San Juan Bay, which cruise ships cross to reach the capital's historic colonial section. Officials say it's home to at least 160 species of birds, 300 types of plants and 124 kinds of fish.

Urban runoff has contaminated much of the estuary, with high amounts of sediment and algae causing massive die-offs of fish. Trash clogging the Martin Pena Channel means there is only one exit to the ocean, choking off natural tidal flow that might flush out debris and other contamination.

"We urgently need this dredged," said Javier Laureano, director of the nonprofit San Juan Bay Estuary Program. "It's like having a heart artery obstructed."

The nearly four-mile (six-kilometer) long Martin Pena Channel once had a second exit, but blockage there has restricted water flow, affecting the salinity of a nearby lagoon and killing wildlife.

The estuary began to deteriorate after rural migrants sprawled across San Juan in the mid-1900s. Development then began crowding the edge of the estuary, often without connecting to the main sewer system.

Nunez recalled how people considered the channel a nuisance because it attracted mosquitoes carrying dengue. He said the government would often drop off construction rubble and old tires near the channel, which residents would then use to build homes.

"There was no environmental consciousness back then," he said. "It was easier to open a kitchen window and throw out the garbage than to walk to the main road."

Earlier this year, the Water and Sewer Authority connected about 1,000 homes nearby to services, but raw sewage continues to flow in large quantities.

The territory's governor revived hopes the estuary could be saved when he recently signed an executive order to create a committee charged with overseeing the dredging project, which has received widespread support from a sharply divided legislature and a majority of Puerto Ricans.

Rodriguez said her corporation aims to start the dredging in 2016 while the water and sewer company has pledged to build a sewage system for some of the 26,000 people who live near the estuary.

Even with the funding challenges, there is some optimism the problems can be solved. Puerto Ricans have already cleaned up a portion of the estuary known as the Condado Lagoon, which once was considered an open sewer but now hosts Ironman competitions.

"This is a man-made problem," said Guy Harvey, a marine biologist and wildlife artist who visited Puerto Rico in late October to help revive one of the lagoons. "We can easily fix this with a little bit of thought and cunning."