The residents of the Mayo Peninsula are serviced by well water. Wells are taps that are drilled into an underground water source referred to as an 'aquifer'. When it rains or snows, some of that water is absorbed into the ground. From there, the water fills the cracks and crevices between the rock and soil and concentrates into the permeable bedrock at the bottom. This concentration of water is called the 'aquifer'. The aquifer is 'recharged' every time it rains or snows. There are many risks to aquifers. Leaking from damaged gas or oil tanks, fertilizers, pesticides, road salt, leaking landfills and septic systems can all pose a hazard to an aquifer. Development poses significant risks as well. Impervious surfaces such as roofs, parking lots and driveways naturally come with more housing and park development. Rain and melting snow run off these impervious surfaces straight into the storm drains and allows for little to absorb into the ground to recharge the aquifer. In turn, the additional runoff raises the water levels in creeks and rivers causing flooding. When there are too many homes tapped into the same aquifer, then there is a possibility that the aquifer could go dry. Other consequences of having too many wells on an aquifer is that saltwater can leach into the aquifer and land that is held up by the groundwater could actually sink.
The capacity of the aquifers serving Mayo is unclear. Some wells have failed. Mayo residents requested a study of aquifer capacity to meet growth projections in 2002, but none was done. Residents again requested a study in 2016 in anticipation of the county's decision to lift the building moratorium. The county agreed to conduct a study, with results expected in summer 2018, but building has resumed and is accelerating.