Crown State Memorial Beach Park in Alameda closed down after "quarter-sized tar balls and an oil sheen" were found along the shoreline, stretching about half-mile long. No one knows yet where the oil is coming from, but many have speculated that it stems from the Cosco Busan (which, as you may remember, dumped over 58,000 gallons of oil in the SF Bay last year.)
According to the Oakland Tribune, neither the Coast Guard nor the state Department of Fish and Game could figure out the oil got there. While samples of the globules are being analyzed -- please be radioactive, please be radioactive, please be radioactive -- the beach is closed until further notice.