A picturesque Massachusetts island best known as a summer playground for the wealthy has a hidden public health problem - and the data is coming straight from the sewers.
Eight months of wastewater surveillance data from Nantucket, the exclusive island off the coast of Cape Cod, shows cocaine levels consistently and significantly above the national average, with peaks reaching nearly three times the typical U.S. concentration. The findings come from the island's ongoing Wastewater Surveillance Program, launched in summer 2025 by Nantucket's Health and Human Services Department as a public health initiative.
Samples are collected hourly at the island's Surfside Wastewater Treatment Facility, which serves roughly 70 percent of Nantucket's residents and visitors, and analyzed by Biobot Analytics, a Cambridge-based firm that spun out of MIT research. The system was originally built to track COVID-19 but was expanded to monitor a wide range of substances including cocaine, methamphetamine, fentanyl, xylazine, nicotine and several prescription opioids.
Initial summer 2025 results showed cocaine concentrations topping 1,500 nanograms per liter, roughly 50 percent above the national average of approximately 1,000 ng/L. But the numbers climbed sharply from there. In mid-October 2025, levels spiked to 2,948 nanograms per liter, nearly three times the national benchmark. A second major spike followed in December at around 2,815 ng/L before levels began declining into early 2026.
By contrast, methamphetamine, fentanyl and xylazine all tested below national and regional averages throughout the testing period.
Nantucket's summer population can quadruple, with as many as 60,000 visitors on peak days, according to local data. Officials said the surge in cocaine readings during high-traffic periods raises questions about substance use among the island's seasonal influx of affluent visitors.
"Nantucket, like communities across the country, is not immune to the growing public health crisis of substance misuse and overdose," the town's public health department wrote on its official wastewater surveillance webpage. Town officials said the goal of testing is not to estimate user counts but to "identify concerning patterns" and guide "timely, evidence-based interventions."
Nantucket Public Health Director Roque Miramontes said the program helps officials tailor outreach and resources when specific drug trends emerge. If a sustained spike in a particular substance is detected, the town has protocols to notify partners including the Nantucket Police Department, Nantucket Fire Department and local substance use recovery services such as Fairwinds counseling center and Addiction Solutions of Nantucket.
The wastewater program costs the town approximately $30,000 annually. No injuries or fatalities have been reported in connection with the cocaine findings. The data does not identify individuals or specific neighborhoods.
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