Hancock County, Mississippi: drinking water report. Hancock County on Mississippi's westernmost coast has about 48,000 residents in communities including
Hancock County on Mississippi's westernmost coast has about 48,000 residents in communities including Bay St. Louis and Waveland. The county draws water from the Miocene aquifer and shallower sand aquifers. Stennis Space Center – NASA's primary rocket engine test facility – occupies a 125,000-acre buffer zone in the northern part of the county, and the former Mississippi Test Operations used hazardous materials that have affected local groundwater.
Stennis Space Center's operations and associated military activities (the Naval Construction Battalion Center is co-located) have generated multiple contamination sites. According to NASA's 2024 environmental report, TCE and perchlorate from rocket engine testing have been detected in groundwater monitoring wells on the facility. PFAS from firefighting foam use at the co-located military facilities has been found at 32 ppt in boundary monitoring wells.
The county's coastal location adds saltwater intrusion risk. A 2024 MDEQ groundwater study found chloride concentrations increasing in production wells along the Bay St. Louis coastline, driven by sea level rise and increased pumping demand during the post-Katrina population rebound.
Hancock County residents near Stennis Space Center should be aware of the potential for perchlorate and PFAS in groundwater. The NASA buffer zone limits residential development near the facility, but the contamination plume extends beyond the buffer in some areas.
Check your water for data at your location. For the combination of rocket-fuel-related contaminants, PFAS, and coastal minerals, reverse osmosis provides the broadest household protection. Our water filter guide covers systems rated for perchlorate removal. Pull your detailed report for local data, and visit our Mississippi page for statewide patterns.