The State Lands Commission has released a report to inform the public and decision-makers about the Chevron 4H shell mounds offshore of Santa Barbara. The report evaluates the effects on public trust resources and values of leaving the shell mounds in place and the potential effects of their removal. The report was developed in response to a proposal by Chevron USA, Inc. to quitclaim (i.e., voluntarily surrender) two oil and gas leases and allow for the shell mounds to remain in place. Staff will present the report to the Commission as an informational item, likely at its April 2 public meeting. If you would like to comment on the report, please submit comments to CSLC.4Hreport@slc.ca.gov by April 30, 2025, or comment during our April Commission meeting.
As background, Chevron decommissioned platforms Hazel, Heidi, Hilda, and Hope, known as the 4H platforms, in 1996. At that time, the shell mounds (remnant debris under each platform created from well cuttings covered by layers of marine detritus and sediment) remained in place subject to a mitigation monitoring program and other stipulations related to commercial fishing around the platforms. The report, independently peer-reviewed by scientists selected by the Ocean Science Trust, assesses over 40 years of studies at the 4H shell mound sites. Notable findings include that potential contaminants within the shell mounds (from well cuttings) appear to remain sequestered within the mounds and are not dispersing into the marine environment, though some risk of contaminant release remains in the event of a significant seismic event.