vary tremendously. In the Edwards Aquifer some water may barely move, while in other areas water may travel miles (thousands of meters) in a single day. On average, the Edwards aquifer has been modeled with a transmissivity of about 100 ft2/day (9.29 m2/day). In the south, the Edwards Aquifer dips beneath the lowland plains of the gulf coast. This area south of the recharge zone is referred to as the Artesian Zone, where the water is held under pressure by low permeability layers, and can flow to the surface without the assistance of pumps through openings like springs and artesian wells. Climate The Edwards aquifer underlies a portion of the Edwards Plateau thus the climate of the Edwards Plateau can be used to describe the climate in the aquifer's region. The eastern portion of the Aquifer falls in a Humid subtropical climate (Köppen climate classification Cfa or Cwa), while the western has a semi-arid steppe climate (BSk and BSh) The average annual temperature on the Edwards Plateau is 66 degrees Fahrenheit and the average annual precipitation amounts to 25.24 inches. The temperatures vary by season with the lowest average temperature occurring in January, 50 degrees Fahrenheit, and the highest temperature occurring in July or August, nearing 85 degrees Fahrenheit for both months. Conversely, January is the month with the lowest precipitation, averaging 1 inch, while May and September average the most, 3 inches. The proximity of the Edwards Plateau to the Gulf of Mexico and its location in the middle latitudes creates variation in the weather patterns experienced between different years, seasons, and months. Water quality Approximately 1.5 million people obtain their drinking water from the Edwards Aquifer. At present, the water quality of the aquifer has satisfied drinking water standards and there have been no significant issues with pollution contamination. Regular water quality testing through the USGS NAWQA Program occurred between 1996 and 2006. On a yearly basis, ions, metals, nutrients, bacteria, pesticides, VOCs, and synthesized chemicals remained below the EPA's published Maximum Contaminant Levels (MCLs). Dissolved nitrates (NO3) are detected throughout the entire aquifer at concentrations that exceeded the national background levels3, but that are well below the MCL (10 mg/L). These nitrates may be the result of agricultural runoff that enters the aquifer through its recharge zone. Due to the karst hydrogeology of the Edwards Aquifer, chemicals that enter the system have the potential to rapidly travel