Drops of rain that fall on the land do not always wash into the Bay or one of its tributaries right away. Instead, precipitation can seep through the soil and into groundwater.
Groundwater is water that is stored underground in cracks and spaces in rocks and soil. Only 3 percent of all water on Earth is fresh water, and at least 30 percent of that fresh water is contained in groundwater.
Groundwater mainly comes from rain and snow, but some human activities can contribute additional water.
Once water has soaked into the ground, it continues moving downward through the earth, where dirt and rock particles filter out any harmful bacteria. Groundwater eventually reaches a layer of impermeable bedrock, at which point it stops and begins saturating the soil in the surrounding area.
Over time, groundwater forms aquifers, which can be tapped using a well. Many local communities throughout the Bay watershed use groundwater as a source of public water.
Natural groundwater pollution occurs when underground deposits of radon, arsenic or heavy metals seep into aquifers. But in the Chesapeake Bay region, human activities pose a significant threat to groundwater.
Pollution gets into groundwater the same way it gets into any other body of water: through stormwater runoff. Just like the runoff that flows directly into our rivers and streams, groundwater can carry pollutants like nutrients and chemical contaminants
According to a 1998 study by the U.S. Geological Survey (USGS), groundwater contributed nearly half (48 percent) of the total nitrogen load to streams in the Bay watershed.
Natural gas drilling and mining can also contribute significant pollution to groundwater.
According to the United States Geological Survey (USGS), groundwater enters the Chesapeake Bay in two ways:
Groundwater contributes to river flow, or the amount of fresh water flowing from streams and rivers into the Bay. In a 1998 study, the USGS found that in an average year, of the 50 billion gallons of streamflow that enter the Bay each day, nearly 27 billion gallons are from groundwater.
It can take years for groundwater — and the pollutants it may carry — to slowly travel through aquifers before reaching the streams and rivers that flow to the Bay. This “lag time” can make it difficult to determine whether efforts to reduce pollution throughout the Bay watershed are having a positive effect on the Bay’s health.
This watershed group is cleaning up the mess that coal mining has left behind.
A new "pollution diet" for trash in the impaired Anacostia River as directed by the federal Clean Water Act
Publication date: July 01, 1993 | Type of document: Report | Download: Electronic Version
The Chesapeake Bay Groundwater Toxics Loading Workshop was held April 15-16, 1992, at the U.S. EPA Chesapeake Bay Program Office. Workshop participants reviewed and discussed available information on results from groundwater studies and…