Switching to a New Regional Groundwater Model in Virginia? Not So Fast

Virginia has an on-going groundwater permitting program for the coastal area. Permits requests are evaluated with a regional groundwater model. The model in use was developed by USGS in the 1990s. Last year, the USGS completed an updated model which was funded by the Hampton Roads Planning District Commission (HRPDC). The model has significant changes:the Chesapeake Bay Impact Crater is included, the deepest and most utililized aquifer was redefined as one aquifer instead of three, the confining units were explicitly modeled, and the model structure changed from 10 layers to 60 layers. The new model's changes have led to the state agency's reluctance to switch to the new model. The presentation will discuss these challenges. Also, the new model indicates that current withdrawals are mining groundwater from the confining units which has caused an increasing decline in head over the last 10 years even though withdrawals have been nearly constant. The presentation will touch on this issue and the fact that the largest groundwater user, which accounted for a third of regional withdrawals, has closed. If the facility is not replaced; the state and region will have a second chance to avoid overallocating the resource. The state is currently revising the permitting regulations so this is the perfect time to consider changes to the groundwater management concept.