Teams from Delray Beach and the University of Idaho are the first finalists in a $10 million competition aimed at identifying ways of removing excess nutrients from waterways.

The Everglades Foundation's four-year competition targets phosphorus, the nutrient behind harmful algae blooms like those plaguing the Indian River Lagoon and other Florida waterways.

The foundation's Tom Van Lent says the Delray Beach team's proposal relies on a natural ocean mineral while the University of Idaho's is based on a plant scrubbing water clean.

"We got applicants that range from quite literally people working on their garages and are inventors in kind of the almost stereotypical image that we have of people working on a major breakthrough in their garage to some very large and sophisticated corporations."

Each team receives $5,000. Nutrient pollution is considered to be among the nation's most challenging and costly environmental problems.

Environmentalists are taking aim at excess phosphorus in Florida waterways and beyond.

The Everglades Foundation is offering $10 million dollars for a cost-effective way of removing the damaging nutrient from freshwater bodies.

The foundation will launch the multi-year, international competition in 2016.

Spokeswoman Maria Garcia says the foundation was moved to action by water releases from Lake Okeechobee that sent polluted water to coastal estuaries.

"That kind of inundated these freshwater estuaries with phosphorus pollution, which then in turn spawned toxic algae blooms, which aside from being smelly are incredibly damaging to the environment and the economy."

Similar blooms in Lake Erie left Toledo without water in 2014, shutting down the city. Phosphorus is common in fertilizers and organic wastes. In large amounts it damages water quality.

The Environmental Protection Agency describes nutrient pollution as among the nation's most challenging and costly environmental problems.