Sewage testing finds cocaine levels 50% above U.S. average on Nantucket

Sewage testing on Nantucket Island this summer found cocaine concentrations roughly 50% higher than the U.S. average, local health officials said, part of a wastewater analysis that also detected traces of fentanyl, methamphetamine, xylazine and prescription opioids.

Samples collected between June 18 and July 28 from the Surfside Wastewater Treatment Facility registered cocaine levels of about 1,500 nanograms per liter, compared with a national average near 1,000 ng/L, according to results posted on the town's website. Fentanyl and methamphetamine levels were lower than national and Northeast regional averages, officials said.

The Surfside plant serves roughly 70% of the island's estimated 14,000 year-round residents; town officials said samples were analyzed by Biobot Analytics, a Cambridge-based wastewater analytics company founded at the Massachusetts Institute of Technology.

Local health officials emphasized that wastewater testing is an emerging tool for monitoring community drug use and that results can vary. "As this activity is still in its early stages, additional baseline data is needed to provide a clearer picture," Nantucket public health director Roque Miramontes said. He added that, for high-risk substances and opioids, "a sustained increase over several weeks may be a stronger indicator for public health intervention."

Clinicians on the island said the findings reflect a distinct summer pattern but urged caution in interpreting a single round of tests. "I think it's interesting that cocaine was so high. And I was surprised fentanyl was so low, because fentanyl is in everything. I thought fentanyl would be higher," said Dr. Timothy Lepore, founder of Addiction Solutions of Nantucket. He said officials plan to repeat testing during the winter months, when the island's seasonal population decreases, to compare results.

Nantucket is a popular summer destination with a substantial influx of visitors and seasonal residents. The town's website and public reporting noted the island's reputation as a summer playground for well-known figures and wealthy visitors, which officials said makes seasonal comparisons important when assessing wastewater signals.

Officials and researchers say wastewater-based epidemiology can offer rapid, anonymized community-level data that complement clinical and law enforcement sources, but they stress that single samples or short testing windows are insufficient to draw firm conclusions about trends or to guide interventions. Nantucket officials said they will continue testing and build a longer baseline before recommending specific public health responses.

The summer testing results were posted publicly as part of the town's ongoing effort to monitor public health indicators. Future sampling, officials said, will seek to determine whether the elevated cocaine signal was a seasonal phenomenon tied to summer visitors or reflective of a broader change in local drug use patterns.