The areas where rainfall directly enters these aquifers is called the zone of recharge. The Nanjemoy aquifer, for example, is recharged through fossil-bearing soils on land scores of miles up the Potomac. Rich with microscopic fossils, it lies hundreds of feet deep beneath my home, layered in sequence with the Aquia and Piney Point aquifers. The aquifers, and their abundant water lay undisturbed, and untapped throughout human history in Southern Maryland until about midcentury, when modern well-drilling equipment made them increasingly accessible for residential, municipal and commercial wells. James Harriman has worked on well and groundwater issues in Calvert County for 26 years, during which time the population has more than tripled.
Many wells can lower the entire water table.
In Anne Arundel County, Maryland, a field of municipal wells had to be shut down in the near past when their cone of depression virtually stopped the flow of a smaller Bay tributary. In the present drought, a Pennsylvania municipal well was recently test pumped for two days, and a nearby well fell 8 feet. Surrounding residential wells within 1,000 feet fell up to 3.3 feet. Aquifers, however large, are not immune to abuse of the water supply. Some test wells have been monitored in Calvert since they were put into production a half century ago.