Late last month, a team of scientists from the California Department of Toxic Substances Control’s Office of Criminal Investigations sampled fragments of treated wood and other debris that remain at the shoreline of Drakes Estero, where the National Park Service dismantled the oyster farm as part of a $4 million restoration project last year. The criminal investigation may be exploring alleged violations of the Hazardous Waste Control Law; in general, the most serious of these cases involve midnight dumping or other unlawful disposal or transport of hazardous waste at unpermitted facilities—as well as the storage or treatment of hazardous waste that creates a danger to the public and the environment. Abbott Dutton, a spokeswoman for the department, could not provide specifics, citing the open investigation. The probe began after Matthew Zugsberger, a former employee of a park contractor who was tasked with helping to remove aquaculture debris and defunct oyster racks, filed a complaint with the state office two months ago. Mr. Zugsberger, who was fired after a few months on the job, sued the contractors last year with a host of allegations, including that they defrauded the park service by disposing of toxic waste pulled from the estero at unauthorized sites. (He also alleges negligence on the job site resulting in his personal injury, and claims he was wrongfully terminated after voicing his concerns.) John Hulls, a former Point Reyes Station resident and a reporter with the Russian River Times who has followed the case extensively, attended the state office’s site visit to Drakes Estero last month. He said scientists on the scene used an x-ray fluorescent scanner that can evaluate toxicity levels in everything from children’s toys to contaminated soil. “Several of the samples showed very high levels of toxics but the [department] stated scanned tests must be confirmed by direct laboratory testing of the samples,” Mr. Hulls wrote in a recent story for the Times. He also drew attention to the visible presence of wood fragments and other debris, despite the contractor having regraded the area after completing the project. As far as the stakes of the criminal investigation, high toxicity levels would contradict the park service’s environmental permitting for the project, which did not assume the presence of toxic material. They would also provide evidence for Mr. Zugsberger’s allegations of chemical burns and his question about the disposal of the material cleared from the estero.