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Important characteristics of the Edwards Aquifer, relative to the quantity and quality of water that is stored in it, include a contributing zone. The contributing zone includes creeks and rivers that drain watersheds and flow to areas where the Edwards and associated limestones are exposed at the surface. As the water flows over and rain falls upon the surface of the Edwards Limestone, it infiltrates through the faulted and jointed cracks, the highly porous rock, and the caves and sinkholes of the Edwards limestone. These characteristics classify the Edwards as a karst aquifer and allow water to rapidly recharge into and through the limestone. 
This area, where Edwards Limestone is exposed at the surface, is called the recharge zone. Eventually, the Edwards Limestone dips below the surface where it is capped by a relatively impermeable layer. The pressure of the water flowing into this portion of the aquifer causes water to rise to a level higher than the level of the Edwards Limestone itself. This is called the artesian zone. Where the confining layer is penetrated by cracks in the limestone or wells through the capping layers, we will find artesian wells and springs. In the extreme eastern section of the aquifer, is an area of decreasing water quality. This water has a higher mineral content and is referred to as the bad water zone. Follow this link to a TCEQ's Edwards Aquifer Viewer, an interactive map of the contributing, recharge, and artesian (transition) zones. It is important to maintain high standards of water quality as water flows through the contributing zone. Any pollution allowed to enter the creeks and rivers in this area may find its way to the recharge zone where it can contaminate the water entering the aquifer, where cleanup or removal is virtually impossible. Care must be taken to ensure that the fractures, caves and sinkholes of the recharge zone are free to allow clean water to enter the aquifer. Covering these recharge features will decrease the amount of water replenishing the aquifer. Allowing polluted water to enter these features will degrade the quality of water stored in the aquifer. Knowing where these features are and how they transmit water through the aquifer may allow us to provide some control over the quantity and quality of water that enters the aquifer. |
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