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U.S. EPA directs public and private efforts to design cleanup plan for Yosemite Slough

Contact Information: 
Michele Huitric ( )

SAN FRANCISCO – The U.S. Environmental Protection Agency has reached two settlements with several parties to begin cleanup of Yosemite Slough, an inter-tidal water channel in the Bayview District of San Francisco. The site contains high levels of contaminants, especially PCBs and lead, which are hazardous for the plants and animals that live in the slough. People can also be at risk if they eat contaminated fish and shellfish.

The Yosemite Slough site is approximately 1,600 feet long and 200 feet wide and located between Hunters Point Naval Shipyard to the north and Candlestick Point State Recreational Area to the south. Depending on the tide, the site is exposed as a mudflat or covered with 3 to 6 feet of bay water. Sources of the contaminated sediment at the site include past industrial and commercial activities, fill material placed along the slough, and urban stormwater runoff.  

The 12 private parties agreeing to the settlement are Ashland, Inc., Coca-Cola North America, Exxon Mobil Corporation, InterState Oil Company, NL Industries, Inc., Occidental Chemical Corporation, Pennzoil-Quaker State Company, PPG Architectural Finishes, Inc., Redwood Oil Company, Inc., Textron, Inc., Tyco Electronic Corporation and Univer USA, Inc. The four public entities involved in a separate settlement are the City and County of San Francisco, the California Department of Parks and Recreation, the California State Lands Commission, and the U.S. Defense Logistics Agency.

The groups will initiate nine technical studies as a basis for the design and implementation of the Yosemite Slough cleanup plan. The site’s cleanup will eventually require removing the top layer of the most contaminated mud from the slough and installing a protective barrier, or cap, of clean sand and mud that will prevent future harmful impacts to San Francisco Bay.

Yosemite Slough once consisted of natural marine habitat including wetlands, marshlands, and tidal mudflats. Between 1900 and 1970, the slough was significantly narrowed by placement of fill soils and debris in wetlands and along the original edges of the slough. By the 1950s, the area surrounding the slough was characterized by mixed residential, commercial, and industrial use.

San Francisco Bay is a designated "estuary of national significance" under the Clean Water Act. The bay and its tributary streams, situated in an urban area with more than seven million people, provide crucial fish and wildlife habitat at the heart of the larger Bay-Delta Estuary. The bay’s users and nearby residents are all potentially affected by threats to its ecological health, including legacy pollutants like mercury and PCBs, polluted stormwater, and the challenges of drought and climate change.

EPA is using the federal Comprehensive Environmental Response, Compensation and Liability Act, also known as Superfund, to guide the cleanup of the Yosemite Slough site. During 2012 and early 2013, EPA developed a cleanup plan, which was released for a formal public comment period in August 2013 and finalized in an Action Memorandum in March 2014.

EPA’s efforts at Yosemite Slough are part of the Agency’s commitment to restoring the health of San Francisco Bay. Since 2008, EPA's San Francisco Bay Water Quality Improvement Fund has provided more than $44 million in competitive grants for 61 projects that are restoring water quality and wetlands, reducing polluted runoff, and greening development in San Francisco Bay and its watersheds. These grantees and their partners represent a network of more than 70 government agencies, resource conservation districts, land trusts, watershed groups, and non-profit organizations across the Bay Area's nine counties. This network has leveraged EPA's funds with an additional $153 million from partner agencies and organizations, resulting in more than $195 million invested in San Francisco Bay and its watersheds.

For more information on the Yosemite Slough site (also known as the Yosemite Creek Sediment site), visit:   

For more on EPA's San Francisco Bay Water Quality Improvement Fund, visit: