The site was polluted by a UC Berkeley Field Station and a Zeneca sulfuric acid manufacturing center. Restoration is underway. The marsh is so polluted that the San Francisco Bay Area Regional Water Quality Control Board named it a "toxic hot spot" and one of the "top 10 most polluted" sites in the Bay Area in 1998. The contamination includes dangerous levels of toxic chemicals and organic compounds such as Arsenic, mercury, and PCBs.