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, 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 (http://www.co.saint-marys.md.us/docs/aquiferstudy.htm), 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.
In 1968 an essay was written by Garrett Hardin (Science, v. 162, p. 1243-1248), which subsequently has been widely quoted. Entitled “The Tragedy of the Commons,” he chose to use public grazing land as an example of a “common” resource, but he could as well have used groundwater, crabs, or any other shared resource. He wrote: “Each man is locked into a system that compels him to increase his herd [use more water, catch more crabs] without limitin a world that is limited. Freedom in a commons brings ruin to all.” In the case of regional aquifers, we are locked into a system that compels us to use the water if it is available, with no regard for anyone but ourselves, or for limitations in the resource. Our motto is: “Use it if you can get it.” As the human population expands, more and more people must “share” diminishing resources. Development in southern Maryland will continue to affect the domestic water supply of Virginians.
There are other examples of groundwater usage in the Virginia Coastal Plain that affect innocent citizens. The most egregious examples involve the two paper mills at Franklin and West Point. These two facilities “mine” (and discard) more than 50 million gallons of artesian water each day, enough for 500,000 people. As reported in the Richmond Times Dispatch (November 14, 2002, Section F), the water withdrawal has caused large cones of depression and between 2 and 3 inches of land subsidence.
The fact that current usage of artesian water is not sustainable is an uncontested fact. The solution(s) to problems of over-utilizing finite resources are obviously difficult, and cross political boundaries. The time has come for regional planners to recognize that we cannot continue to “mine” our artesian water at the current rate. We must address this difficult issue on appropriate time scales, certainly more than a few decades. Meanwhile, water levels continue to decline at rates of more than one foot each year, and Virginians continue to replace wells because of water usage in Maryland. We are seeing only the tip of the iceberg.
Illustration: Map of water levels in the intermediate artesian aquifer in southern Maryland, modified from USGS Open-File Report 00-83. Water levels are in feet below sea level. The boxes in Virginia are tax map parcels in Northumberland and Westmoreland counties. The number of artesian wells that failed in each tax parcel because of declining water level, between 2000 and 2002, is indicated in each box. Withdrawal in Maryland is obviously responsible for localization of these failed wells. The data are from local Health Department records.