Development of groundwater supplies in Shenandoah National Park, Virginia

DeKay, Richard

This report describes the development of groundwater supplies at Shenandoah National Park. Included in the report are discussions of general geology, the upper Precambrian formation, lower Cambrian igneous, clastic sedimentary rocks, springs, a test-drilling program, potential yields, and management recommendations. Contained in the report are temperature rock records, rock formation, relationships of temperature, precipitation, stream flow, drilling records for all study wells, and drainage patterns. Shenandoah National Park encompasses more than 300 square miles in portions of eight counties located in the Blue Ridge Mountains of northwestern Virginia. Thirteen geologic formations comprise the bedrock of these mountains and their foothills, eight of which occur on the lower west slopes and one on the lower east slope. The other four rock units underlie the upper portion of the eastern slope and the mountain crest ; these formations are of late Precambrian and early Cambrian age, and are comprised of basaltic, granitic, and clastic sedimentary rocks. Existing public facilities in the Park are located on these impermeable rocks near the crest of the mountains, and water supplies are premium requirements. Springs furnished water to all Park facilities from its inauguration in 1936 until 1961, but expansion of facilities had greatly increased the water demand. Efforts were made to recondition existing springs and to locate additional ones for development, but the former was unsuccessful and the latter either too far from areas of water consumption or unreliable during the summer months. From 1961 to 1971 the Virginia Division of Mineral Resources located test-hole drilling sites in predesignated areas along the mountain crest, and preliminary data indicate 20 of the 33 test holes drilled for water can be converted into wells with yields that exceed the summer flows of developed springs.