A Maryland company completed its purchase of four hydroelectric dams along one of North Carolina’s longest rivers, ending nearly a century of ownership under the 128-year-old company that invented modern aluminum processing, Alcoa Inc.

The Yadkin River dams were built a century ago to power an Alcoa aluminum smelter that once employed 1,000 workers but closed in 2007. Alcoa has made about $200 million since then by selling the electricity to commercial customers.

Local residents began questioning why Alcoa should be in charge of the hydroelectric system when it no longer needed the electricity to run the Badin plant, spurring fights among city governments, the state and Alcoa.

Alcoa received a new federal license in December for its plants along the 200-mile Yadkin River waterway that passes farmland, drains the urban landscapes of Winston-Salem, Statesville, Lexington and Salisbury, and fans through seven man-made reservoirs.

“Investing in clean power in North Carolina has long been a goal of ours,” said Cube Hydro’s Chief Executive Officer Kristina Johnson, former U.S. undersecretary of energy in the Obama administration and former dean of Duke University’s engineering school. “We look forward to partnering with local leaders surrounding the Yadkin River to innovate and produce economic, environmental and social benefits for our new neighbors who live and work here.”

Opponents to the Alcoa re-licensing questioned the company’s plans to clean up environmental problems at nearby Badin Lake.

Bethesda-based Cube Hydro Partners announced its plans to buy the plants last July, before federal regulators granted Alcoa the operating license, which extends through 2055. The license was transferred to Cube Hydro in December.

Cube Hydro now operates 19 plants on ten rivers in New York, Pennsylvania, Virginia, West Virginia and North Carolina, generating enough electricity to power about 140,000 homes with renewable energy.

Neither Alcoa nor Cube Hydro has disclosed the price of the deal. Alcoa trades on the NYSE under the ticker AA, and Cube Hydro is a private company.