Test well sites and preliminary evaluation of ground-water potential in Tortola, British Virgin Islands

Moderate supplies of potable ground water are believed to be available in the Roadtown and Paraquita Bay areas, and small, possibly brackish supplies in the Long Look and West End areas of Tortola. Two water bearing units of the same hydrologic system have the potential of yielding water to wells: 1) alluvial deposits, possibly as thick as 60 feet and locally containing beds and lenses of gravel 1 to 5 feet thick; and 2) fractured and jointed bedrock, especially where it is overlain by alluvium.

The most productive ground-water areas are expected to be the lower reaches of the larger valleys. Here the alluvial deposits are thickest and the valleys often follow the trace of fault or fracture systems in the bedrock. A potential yield of 195,000 gpd (U.S. gallons per day) is estimated to be available in the Road Bay area, 55,000 gpd in the Long Look area, and 8,000 gpd in the West End area.

Sites are suggested for test and monitoring wells in the lower courses of six of the valleys on the south coast.