Wastewater testing on Nantucket has revealed cocaine levels consistently exceeding national averages, with October spikes reaching nearly three times the typical U.S. concentration.
Data collected over eight months at the island’s Surfside Wastewater Treatment Facility showed cocaine levels peaked at almost 3,000 nanograms per liter in mid-October, compared to the national average of approximately 1,000 ng/L, according to local news reports. Additional spikes occurred in December, when concentrations climbed to roughly 2,700 to 2,800 ng/L before decreasing in early 2026.
The testing program, which costs the town approximately $30,000 annually, is conducted by Biobot Analytics, a Massachusetts-based company that also monitors Nantucket’s wastewater for viruses like COVID and influenza. Samples are collected hourly over a 24-hour period at the treatment facility, which processes waste from about 70 percent of the island’s population.
Health Director Roque Miramontes emphasized that the focus is on tracking local trends rather than making direct comparisons to national data. “This activity is still in its early stages, and additional baseline data will help provide a clearer picture,” he said.
While cocaine levels remain elevated, the testing revealed consistently low levels of other substances. Fentanyl has remained near non-detectable levels throughout most of the testing period, while methamphetamine and xylazine have tested well below regional and national averages. Prescription opioids like codeine, hydrocodone, and oxycodone have also tracked below national averages, according to graphics provided by the Health Department.
Town officials note that elevated cocaine readings don’t necessarily indicate a surge in use. When cocaine increases without a comparable rise in its metabolite benzoylecgonine (BZE), as happened in some of Nantucket’s data, it may indicate that some of the substance entering the wastewater wasn’t metabolized. This can occur when unused drugs are discarded or when cocaine is used with alcohol, which affects how efficiently the body breaks down the drug.
The wealthy island enclave, known as a summer destination for affluent visitors, has drawn attention for these findings. In May 2025, authorities announced what was described as the largest cocaine-related drug bust in Nantucket history, with more than 5½ pounds of the drug seized in a single raid.
If sustained increases in drug levels are detected, town officials have protocols to notify partners including the Nantucket Police and Fire Departments, Fairwinds counseling center, and Addiction Solutions. “If there were a sustained increase in opioid levels above baseline, we’d probably reach out to first responders,” said Health and Human Services director Jerico Miele when the testing began.
The wastewater monitoring program continues to provide valuable data for public health planning, with officials noting that a spike in flu levels detected in early December was followed by a rise in reported cases, demonstrating the value of wastewater monitoring as an early warning tool.
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