SAN DIEGO (CNS) - California Attorney General Xavier Becerra and the San Diego Regional Water Quality Control Board Monday submitted a 60-day notice of intent to sue a federal agency regarding several years of sewage flow from the Tijuana River into U.S. waterways.

In the notice, Becerra and the board allege the United States Section of the International Boundary and Water Commission, which is tasked with seeking binational solutions to issues, has let more than 12 million gallons of untreated sewage flow into the U.S. since 2015.

"For far too long, uncontrolled sewage spills have polluted and impaired the Tijuana River Valley and Pacific Ocean. This must stop," Becerra said. "It's our duty to protect the public health and natural resources of the people of California. We will do what is necessary to get those responsible to clean up this mess."

The notice claims the commission violated the Clean Water Act by not adequately addressing wastewater flows from the South Bay International Wastewater Treatment Plant located near the border.

Sewage flow has sickened people and led to beach closures as far north as Coronado, in the process irritating a wide variety of government, environmental and recreational stakeholders.

"These polluted flows are a dire threat to both human health and the sensitive wildlife in the estuary and Pacific Ocean near our international border," water board Executive Officer David Gibson said. "Residents of both sides of the border near this waterway and its outfall deserve better and we have an obligation to act."

Senate President Pro Tem Toni Atkins, D-San Diego, praised Monday's action by Bacerra and the water board.

"The coastal communities of San Diego County depend on clean, healthy watersheds and beaches -- recreationally, economically and for our rich environmental and biological tapestry. In recent decades, the federal government has turned a blind eye toward the sewage, trash and debris flowing across the border from Mexico," she said.

The intent to sue comes as the Port of San Diego and cities of Chula Vista and Imperial Beach forge ahead with their own lawsuit alleging the federal government is violating two U.S. laws that protect water quality and public health. The suit, filed in March, also targets the private operator of a treatment plant that serves Tijuana.