New York, NY—New York’s harbor is getting a facelift, thanks to the Billion Oyster Project.

The Billion Oyster Project—a largely student-operated project that just hosted its 15thanniversary celebration—looks to restore the oyster reefs that once existed in the harbor. The goal, specifically, is to have one billion live oysters distributed around 100 acres of reefs by 2035. The stats on their website are encouraging: 28,000,000 oysters restored; 19.7 trillion gallons of water filtered; 72,500 pounds of nitrogen removed; and 1,000,000 pounds of shell reclaimed and recycled.

According to NPR, it starts with restaurants, which leave their discarded oyster shells to be picked up by The Lobster Place. The Lobster Place, a seafood supplier and the Billion Oyster Project’s partner, then trucks them over to Brooklyn. Once a month, the shells move from there to Governors Island, where they sit out in the elements for a full year, which removes all contaminants.

A public high school on Governors Island get the shells next, where they receive larvae grown by the students, which build their own shells and mature. And then they go into the New York Harbor.

Madeline Wachtel, the Project’s director of strategic projects, says that “Oyster reefs provide great marine habitat, similar to coral reefs, with nooks and crannies to protect juvenile fish, and are active food for some species. They help to create a thriving ecosystem.” They also provide a natural breakwater, which can protect the city against a hurricane’s waves.

New York Assemblywoman Linda Rosenthal hopes to pass a bill granting participating restaurants a tax credit.

The Project’s executive director, Pete Malinowski, says that the water quality has improved measurably, and biodiversity has increased wherever they have built a reef.