The U.S. has pledged to help clean one of Puerto Rico's most polluted waterways in a move that ends a 15-year struggle to eliminate raw sewage and garbage from a community where thousands of people live.

The agreement signed Friday by the U.S. Environmental Protection Agency and others marks the start of an extensive, multimillion-dollar cleanup of the Martin Pena Channel. It is part of the San Juan Bay Estuary and home to more than 25,000 people.

Officials aim to remove 800,000 cubic yards of garbage and sediment that would impact 6,600 acres worth of estuary habitat. The cleanup also aims to reconnect a bay and lagoon by excavating a solid mass of garbage that blocks the channel's entrance and cuts off the ocean's natural flow.