The researchers studied saltwater movement in the Potomac aquifers near Lee Hall, Virginia. They used a computer model to see how saltwater could intrude into the aquifers. The simulations showed that the direction of groundwater flow and the type of rocks in the aquifers control where saltwater moves. They found that saltwater could move laterally in the Lower Potomac aquifer and up towards a well in the Middle Potomac aquifer. Saltwater could also migrate from the Middle and Lower Potomac aquifers to the east of the well.