Wells in Virginia Go Dry as Maryland Withdraws Water
(Published February 2003)
Citizens of Virginia’s Northern Neck, between the Potomac and Rappahannock Rivers, exclusively use groundwater for their potable water supply. About 25% of the people use shallow wells that tap the water table aquifer. Other citizens, including all public water supplies, rely on one of two artesian aquifers. The shallow artesian aquifer is at depths of several hundred feet, whereas the deep artesian aquifer is typically at depths up to about 600 feet. Below the deep artesian aquifer the water becomes too salty to drink.
Water levels in artesian wells have declined steadily since wells were first drilled in the early 1900’s. At that time the wells flowed at the land surface. Water levels in the only two monitoring wells that tap the deep artesian aquifer are now 136 and 174 feet below the land surface. Water levels are declining at approximately 1.5 feet each year. No additional data are available in Virginia’s Northern Neck, but we can be sure that water levels are not declining uniformly. Declines are certainly higher where withdrawals are largest. Water withdrawal greatly exceeds any potential recharge that may be taking place, as is proven by the declining water levels. We are “mining” our water, and the practice is unsustainable.
The intermediate artesian aquifer is extensively used in southern Maryland, where data are much more abundant. Viewed on a map (see the illustration), water levels deepen toward a large center of usage near Lexington Park and Solomons Island, defining a “cone of depression.” Water is flowing in all directions toward the center of that cone, where withdrawals are greatest and where water levels are deepest (depressed). The water level at the center of that cone is more than 140 feet below sea level. Water levels drop more than 100 feet between the Virginia shoreline and the center of withdrawal. Water is flowing “downhill” from Virginia into Maryland.
In the last three years (this Stewardship Tip was originally published in January 2003), 63 artesian wells in Virginia along the Potomac River, immediately south of the cone of depression in Maryland, have gone dry (see the illustration). The wells were drilled many years ago, to depths of several hundred feet, using small diameter pipe. “Suction pumps” were installed, which are only capable of drawing water up from depths of about 30 feet. Water levels have dropped below the capability of the pumps, causing the wells to go dry. People are now forced to drill new, larger diameter, wells and use different kinds of pumps.-
Based on the distribution of the wells that have gone dry, there can be no doubt that withdrawals in southern Maryland are responsible. If local effects of the 2002 drought were responsible, wells would be uniformly scattered throughout the Northern Neck, not clustered just southwest of the cone of depression. The drought may, of course, have caused Marylanders to use more water.
Southern Maryland is aware of their growing water problem, although they seem not to recognize that Virginia is involved. Groundwater is a regional resource, not constrained by lines humans draw on maps. Water law can be simply stated: “First in time is first in right.” Maryland is doing nothing illegal in using the water first.