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From Florida to California, communities are struggling with large algae blooms. The algae chokes lakes and estuaries and sometimes are toxic. In many coastal areas, communities are beginning to tackle a major contributor to offshore pollution, residential septic systems. NPR's Greg Allen has this report from Rockledge, Fla.
GREG ALLEN, BYLINE: The Indian River Lagoon on Florida's Atlantic coast is a unique place. Scientists say it's one of the most biodiverse ecosystems in the Northern Hemisphere. But in recent years, the lagoon has had problems.
VIRGINIA BARKER: In 2011, we experienced our first super bloom, which was an enormous algal bloom that spanned about 90 miles of the 156-mile-long lagoon.
ALLEN: Virginia Barker heads the Department of Natural Resources in Florida's Brevard County. That 2011 bloom killed off huge tracts of seagrass and began an almost annual die-off. In 2013, hundreds of dolphins, manatees and pelicans died. Last year, Barker says, the lagoon saw its worst-ever fish kill.
BARKER: Hundreds of thousands of tons of dead fish floating on the surface - very smelly. Clearly there was something toxic that caused that. That created fear in the community.
ALLEN: Across the U.S. and around the world, harmful algal blooms are on the rise. In this country, they become chronic problems in places like Lake Erie, Long Island Sound, and the Gulf of Mexico.
BRIAN LAPOINTE: And it's directly related to the increasing nutrient loads that we're seeing in our coastal waters.
ALLEN: Brian Lapointe, a researcher at Florida's Harbor Branch Institute, says the pollution is directly related to coastal development. Water managers in coastal areas have done a lot to clean up agricultural runoff, storm water and releases from sewage treatment plants. Despite that progress, though, algal blooms continue. Along the Indian River Lagoon, Lapointe identifies a major factor. Hundreds of thousands of homes have septic tanks.
LAPOINTE: And the more research we do and others do, we now realize that they're a much bigger problem than was thought.
ALLEN: In Florida, alarmed by what's happening in the lagoon, many communities are beginning to take action. In the town of Rockledge just across the lagoon from Cape Canaveral, work crews are taking nearly 140 homes in an aging subdivision off of their septic systems and connecting them to the town's sewage treatment plant. Jim Elmore is the town's wastewater director.
JIM ELMORE: There's a lot of excavation. All the roads had to come up, sanitary sewer lines put down the center along with manholes and a lift station installed.
ALLEN: For the homeowners here, the good news is they don't have to pay for the hookups which typically cost $10,000 or more. Last fall, voters in Brevard County approved a half-cent sales tax to fund efforts to clean up the lagoon. The city and state are also chipping in. Brevard County's director of natural resources, Virginia Barker, says after decades of relying on septic systems, communities like hers now have to go to homeowners with a difficult message.
BARKER: You know, it has been challenging to get people to understand that even a properly functioning, properly cited, legally permitted septic system could still be harmful to the Indian River Lagoon.
ALLEN: Florida's beginning to talk about a possible state program to replace septic systems. It's a conversation that's beginning not just here but also in Long Island, Cape Cod and other coastal areas that are grappling with offshore pollution. Greg Allen, NPR News, Rockledge, Fla.
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