Map: Karina Alvarez, USC Sea Grant

Sea Grant releases Deep Ocean DDT+ report

The report details urgent research needs to address the deep ocean DDT contamination off the Southern California coast.

The University of Southern California (USC) Sea Grant Program and the California Sea Grant Program jointly announced today the release of a new report detailing what research is needed most urgently to address the deep ocean DDT contamination off the coast of Los Angeles. The report is the unique culmination of a nine-month collaborative and inclusive process to engage the perspectives of leading scientists as well as those of policy, nonprofits, federal and state agencies, formal and non-formal educators and education centers, tribal representatives, anglers, aquatic recreation communities, and interested members of the public.

"This report incorporates the voices of numerous stakeholders to identify major concerns around ocean dumping of DDT waste,” says Dr. David Valentine, Professor at the University of California, Santa Barbara. “The report offers a pathway by which the scientific community can effectively address critical questions relevant to environmental and human health."

DDT, an insecticide banned in 1972, has harmful impacts on wildlife and potential carcinogenic effects on humans. The contaminated areas within the San Pedro and Santa Monica Basins fall outside the Environmental Protection Agency’s Montrose Superfund site. Recent research illuminates new concerning aspects of this deep ocean DDT—a much broader suite of DDT breakdown products and related byproducts (more than 45 compounds collectively referred to as “DDT+”) that may have toxic effects and have not historically been monitored in the environment.

The unknowns about this deep ocean DDT+ instigated a call to action by researchers, national and state leadership, and the broader Southern California community. In response, the USC Sea Grant Program, based in Los Angeles, and the California Sea Grant Program, based in San Diego—both a part of the national network of 34 Sea Grant programs under the National Oceanic and Atmospheric Administration—jointly conducted a research needs assessment in 2022 and developed the subsequent research needs report.

Titled A Deep Ocean DDT+ Research Needs Assessment of the Southern California Bight, the newly released report provides a comprehensive agenda for critical, deep ocean DDT+ research to inform future action to protect marine and human health.

The federal government appropriated $5.6M for studies on the San Pedro Basin DDT dump site, an amount which the State of California intends to match in spending on DDT+ initiatives between 2023 and 2025. This impending funding makes this report timely and critical for leveraging the greatest impact quickly from these dollars.

“This report provides a critical roadmap for priority research needs to increase understanding of DDT impacts and identify solutions to protect marine ecosystems and human health from ongoing harmful effects,” says Jenn Eckerle, the newly appointed Deputy Secretary for Oceans and Coastal Policy at the California Natural Resources Agency.

Altogether, this report provides a pathway to inform transparent and inclusive investment decisions—and eventually management decisions—about deep ocean DDT+ contamination in the Southern California Bight.

The report is available on a joint website created by California Sea Grant and USC Sea Grant.

Authors of the report are Amalia Almada, Ph.D., USC Sea Grant; Lian Guo, Ph.D., California Sea Grant; Charlotte Stevenson, M.S., USC Sea Grant; Leah Shore, M.S., USC Sea Grant.

This work was supported in part by the National Sea Grant College Program, National Oceanic and Atmospheric Administration, United States Department of Commerce, under grant number NA22OAR4170104, and by the USC Wrigley Institute of Environmental Studies.


Approximate location of 14 known deep ocean disposal sites off Southern California. Disposal Sites #1 and #2 are confirmed DDT disposal sites. The established U.S. EPA Superfund site near Palos Verdes, California, is also depicted (solid red line). Map credit: K. Alvarez, USC Sea Grant


Kate Murphy

California Sea Grant Communications Specialist; 513-581-0349

About California Sea Grant

NOAA’s California Sea Grant College Program funds marine research, education and outreach throughout California. Headquartered at Scripps Institution of Oceanography at the University of California San Diego, California Sea Grant is one of 34 Sea Grant programs in the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce.