A Groundwater Management Strategy Based on Hydrogeologic Studies in a High-Growth County

Loudoun County, Virginia has established  a pre-development, science-based study approach to groundwater resource management.  As one of the nation’s fastest growing counties, Loudoun County, located in Northern Virginia, has emerged with some of the most studied groundwater resources, serving approximately 25% of the County’s 280,000 residents, either through private wells or public water supply wells. 

In response to rapid development experienced over the last several decades, the County Government has developed regulations designed to monitor and protect water resources.  The County requires that all proposed subdivisions of ten or more lots that will be served by individual wells submit a Hydrogeologic Study for approval by County staff prior to acceptance of an application for subdivision.  County requirements for Hydrogeologic Studies also apply for any proposed development (commercial, industrial, or residential) that will withdraw groundwater at a rate greater than 10,000 gallons per day average over any 30-day period.  Separate requirements have been developed for resource extraction. County staff reviews these reports to determine if groundwater resources are adequate for the proposed development use. 

The groundwater management strategy has created an extensive groundwater database.  To date, 175 Hydrogeologic Studies have been submitted, cataloguing over 2000 aquifer tests providing the County with comprehensive data on yield, transmissivity, storativity, specific yield and water quality.  The database also includes domestic well yield and pre-construction water level data for over 9,000 wells, construction information for 14,000 wells, real-time water level monitoring in 19 wells, and over 4000 water quality samples.  These data provide the historical backbone for the County’s Water Resources Monitoring Program, initiated in 2001 to provide the data needed to enable County officials to make informed policy decisions about long-term water resource use, protection, and restoration.