| Summary |
The groundwater resources in Bertie County, North Carolina are limited. Overdevelopment of the groundwater system in a 16-county area bordering Bertie County to the south has lead to state-imposed regulations of groundwater withdrawals from the Cretaceous aquifers. A detailed county-wide hydrogeologic framework of Bertie County has not been previously conducted. This study is intended to develop a more detailed understanding of the groundwater resources in this county. To better understand the hydrogeologic system in Bertie County, five objectives were developed: 1) create a series of maps depicting each aquifer and confining unit identified, including elevation, isopach, and isoconcentration maps, 2) determine the hydraulic properties of the aquifers by calculating transmissivity values for each aquifer at each relevant well location, 3) create four cross-sections, two in the dip direction and two along the strike of the aquifers, 4) provide estimates for recharge rates and the safe yields of the aquifers, and 5) relate the results of this study to other studies of the surrounding counties. Data used to meet these objectives included geophysical logs, driller's well logs, 24-hour aquifer pumping tests, chemical analyses, and historic groundwater levels. This study of Bertie County has demonstrated that the underlying aquifers dip and thicken to the southeast. Interpretations have resulted in a refinement of the understanding of the areal extent of the aquifers, and a more detailed geochemical interpretation of the groundwater beneath Bertie County. In comparison with previous studies of this region, the hydrogeologic characteristics of the aquifers and confining units, including elevation, thicknesses, and transmissivity values, are better defined due to the finer scale and scope of this work. The elevation maps, isopach maps, and cross-sections illustrate that the aquifers underlying Bertie County dip and thicken to the southeast. Isoconcentration maps indicate that the concentrations for chloride, sodium, and fluoride increase to the south and to the east, while iron concentration decreases to the south and east. Currently, the actual safe yields of the Black Creek, and the Upper and Lower Cape Fear Aquifers underlying Bertie County are being exceeded by groundwater withdrawals from those aquifers. In almost half of the wells screened in deeper confined aquifers, the groundwater meets the National Primary Drinking Water Regulations set forth by the Environmental Protection Agency (EPA). Of the 17 water supply wells identified in Bertie County, seven did not meet some of the guidelines set forth in the National Secondary Drinking Water Regulations. Water in most of the aquifers in Bertie County has a high quality, and requires little to no treatment to produce potable water. |
