Well Water in Hancock County, Maine

Hancock County · Population ~55,000 (county); seasonal population much higher · Aquifer: Bedrock / Glacial Till / Coastal Surficial

Hancock County in Downeast Maine is home to Acadia National Park, Mount Desert Island, and a coastline that attracts millions of visitors annually. The year-round population depends almost entirely on private wells, and the seasonal population surge puts additional stress on local aquifers. The county's complex geology — a mix of granite, schist, and volcanic formations — produces variable water quality that can change dramatically from one property to the next.

Variable Geology, Variable Water

Hancock County's geology is unusually complex. Mount Desert Island alone contains multiple rock types — granite, gabbro, schist — often in close proximity. This means neighboring wells can produce completely different water chemistry.

Arsenic tends to be highest in wells drilled into granitic bedrock, which is prevalent across much of the county. Areas with different rock types may have lower arsenic but higher concentrations of other metals.

The practical implication: your neighbor's water quality tells you nothing about yours. Every well needs its own testing.

Seasonal Population and Water Stress

Hancock County's population can triple during tourist season. Bar Harbor, Southwest Harbor, and the smaller coastal towns see enormous seasonal demand on groundwater resources.

This matters for well owners because heavy pumping during summer can:

Coastal and Island Wells

Wells on Mount Desert Island and the smaller islands face unique challenges. The freshwater lens sitting atop saltwater is thin, and over-pumping can break through to brackish or salt water below. Once saltwater enters a well, it can take years for the aquifer to recover.

If your well is near the coast and you notice any change in taste (salty, metallic), test immediately for chloride and sodium. Early detection of saltwater intrusion gives you the best chance of saving the well.

Testing Priorities

Test for arsenic (free through Maine CDC), radon, bacteria, and nitrate at minimum. Coastal and island wells should add chloride, sodium, and conductivity. If near known sludge sites, add PFAS.

See our testing guide for labs and programs.

Every well is different. Two wells on the same street can produce completely different water. The data on this page reflects documented conditions in the Hancock County area, but the only way to know what's in your water is to test it.

Sources

  • Maine Geological Survey — Bedrock Geology of Hancock County
  • Maine CDC — Arsenic Testing Program
  • USGS — Saltwater Intrusion in Coastal Aquifers
  • Maine Geological Survey — Mount Desert Island Geology