The initial flow of the major streams within the seven-county area comes from seeps and springs, primarily from the Edwards-Trinity aquifer. Groundwater in the area is generally available from the strata of Hickory Sandstone, Ellenburger Limestone, Hensell Sand and Edwards Limestone.
Did You Know?
An invasive plant that Lyndon B. Johnson National Historical Park has problems with just happens to be a non-native grass called Johnson Grass. Besides being tough to get rid of, it is poisonous to livestock if eaten just after a freeze. (photo ©Barry A. Rice/The Nature Conservancy)