How Much Cocaine Is In Nantucket's Sewage? A Lot

Eight months of wastewater surveillance data show consistently elevated levels of cocaine in Nantucket’s sewage - with spikes in October and December 2025 that were nearly three times the national average - even as island police have made several high-profile cocaine busts, including the largest in the department’s history.

The levels of other harmful substances in Nantucket’s wastewater, including fentanyl and meth, are far below regional and national levels, and even nicotine levels have largely remained below average. But the cocaine concentrations, which dramatically outstrip benchmarks for the region and the country at large, have drawn the most attention, making national headlines.

When the body metabolises cocaine, most of it is converted to benzoylecgonine (BZE), the primary substance used in urinary drug tests for the stimulant. When cocaine levels rise, BZE levels usually follow. But despite the strikingly high levels of cocaine in Nantucket’s wastewater, BZE levels have mostly remained close to the national average, aside from a couple of significant spikes.

“Because Nantucket’s cocaine levels are above national and regional averages while BZE is often at or below average, the most likely explanations include dumping events, repeated small-scale disposal, or concurrent use with alcohol, which changes how cocaine is metabolized,” a note on the monitoring website reads in part.

Nantucket’s wastewater isn’t monitored for alcohol content.

Health director Roque Miramontes echoed these explanations.

“Certainly, dumping is a possibility,” he said. “Another is when cocaine is consumed with alcohol, it changes the metabolite that’s developed.”

Human services director Jerico Mele previously said that the wastewater surveillance data would help Nantucket understand baseline levels for drug use and monitor whether those rates were rising or falling throughout the year or between years. In the data collected so far, cocaine levels appear to have spiked between October and December 2025.

“We released this data with the goal to provide near real-time, ground-level information to our behavioral health partners to implement interventions and to medical providers so they can learn to ask the right questions and provide treatment when available,” Miramontes said. “If the release of this data contributes to even one intervention that saves a life, then it's worth far more than the $30,000 the town pays to carry out this initiative every year, and that's why we're doing it.”

The town’s surveillance efforts for dangerous substances grew out of previous efforts to measure the amount of respiratory illness on the island. During the COVID-19 pandemic, Nantucket joined many other communities throughout the country in tracking the virus using wastewater. Wastewater surveillance can be a highly effective tool for tracking illnesses in a community, as it does not rely on individuals volunteering to be tested, and can even detect cases before they are symptomatic. Nantucket later expanded its efforts to also track influenza and RSV.