Clark County Aquifer Appraisal

Problem

The Northern Shenandoah Valley is underlain by karst and fractured-rock aquifers that are increasingly being relied upon to supply water to local communities and individual residences. This is an area with an expanding economy and a growing population, and, to meet future water needs, these aquifers are likely to be developed to supplement current withdrawals. The recent prolonged drought has focused attention in Clarke County, Virginia on the quantity and sustainability of the ground-water resources. An improved understanding of these complex aquifer systems is required to effectively develop and manage them as sustainable water supplies. In order to assess current and future hydrologic conditions within the County, a long-term monitoring network needs to be designed and implemented. Furthermore, hydrogeologic information provided by a detailed aquifer appraisal will provide useful information to better address questions about (1) the quantity of water available for use, (2) the effects of increased pumpage on ground-water levels and instream flows, and (3) the quality of the ground-water supply and its vulnerability to current and potential future sources of contamination. The area to be considered in this proposed study encompasses both the carbonate and non-carbonate rocks in Clarke County, Va. Water-quality protection efforts—as outlined in the Water Resources, Groundwater Resources, and the Surface Water Resources Plans—are included in the County's Comprehensive Plan. These efforts are based on previous investigations that have been conducted in the County since the late-1980s. The establishment of a long-term data network and further evaluation of information from previous studies will be part of this proposed hydrogeologic assessment, and will aid future land-use and water-supply planning activities in the County.

Objective

The objective of this study is to better characterize the aquifer systems in the Northern Shenandoah Valley and provide relevant hydrogeologic information that can be used to guide the development and management of these water resources in Clarke County.

Relevance and Benefits

This study will provide hydrogeologic information and data on the aquifer systems in the Northern Shenandoah Valley of Virginia. Water-resources information from this study will be used by multiple parties for planning and operational purposes. Additionally, this study, in conjunction with the on-going studies in Frederick (VA0134) and Warren Counties (VA0142), Va., will be the foundation for a future regional assessment of the Northern Shenandoah Valley of Virginia.

Approach

This study will be conducted as a long-term appraisal of the Northern Shenandoah Valley aquifer systems in Clarke County with two major components: long-term monitoring and hydrogeologic assessment. The first component will consist of the design and implementation of a long-term network to monitor ground-water levels, streamflow, and spring discharge. The second component will consist of a hydrogeologic assessment of the water resources in the County. Six major work elements will be included in the assessment: (1) Hydrogeologic Framework, (2) Ground-Water Flow System, (3) Water Budget, (4) Water Quality (including aquifer susceptibility), (5) Geographic Information System Coverages, and (6) Information Assessment. The assessment phase of the appraisal will be completed in four years beginning in August 2002.

Clarke County Real-Time Water-Monitoring Networks provides access to surface water, groundwater, and water-quality monitoring sites location and data links for active sites.