FAQ

Groundwater is water that can be found under the earth’s surface, stored in the cracks and spaces between particles of soil, sand and rock. Groundwater comes to the earth’s surface when it flows through a spring or into rivers, streams and lakes. Scientists with the U.S. Geological Survey (USGS) have found that in an average year, almost 27 of the 50 billion gallons of streamflow that enter the Chesapeake Bay come from groundwater.

Groundwater can become contaminated when pollutants on the land seep into underground aquifers. A number of human activities can pose a threat to groundwater, including leaking or damaged storage tanks of gasoline or oil; abandoned containers or uncontrolled spills of hazardous waste; fertilizers, pesticides or road salts applied to lawns, fields and roads; and leaking landfills and septic systems.

Contaminated groundwater can push pollutants into the Chesapeake Bay. The slow movement of polluted groundwater into the Bay can lengthen the “lag-time” between the adoption of a pollution-reducing practice and the positive effect of that practice on a particular river or stream. This means slow-moving groundwater could push nutrient pollution into the Bay even after we have lowered the amount of nutrients we put on the land.