Building a subdivision can be tough in an area that has limited groundwater supplies. Just ask any contractor in Phoenix. They have to assure a 100 year water supply to the homeowner.
Going beyond the basic coliform test, the Arizona Department of Water Resources (ADWR) Assured and Adequate Water Supply Programs were created to address the problem of limited groundwater supplies in Arizona. The Adequate Water Supply Program acts as a consumer advisory program, ensuring that potential real estate buyers are informed about any water supply limitations. Under the continuous water availability criteria, water providers or developers must demonstrate that the water supply is uninterruptible for the 100-year period, or that sufficient backup supplies exist for any anticipated shortages. For groundwater, a study must consider demands of area users for a 100-year period, and projected water levels may not exceed depth limitations specified in the rules. These stringent requirements have been in response to the ongoing drought in the state.
Other states are not so stringent. In Oklahoma, domestic wells are essentially unregulated. The Oklahoma Water Resources Board (OWRB) must view applications to determine if nondomestic wells have a beneficial use, as well as ensure that waste by pollution or waste by depletion will not occur. In addition, the groundwater withdrawal must not violate Oklahoma Water Quality Standards, or take more fresh groundwater than is authorized by the permit. The Board may also impose additional conditions on the groundwater applicant.
To arrive at the amount specified in an Oklahoma groundwater permit the OWRB conducts maximum annual yield (MAY) studies to determine amounts of water that may be withdrawn from Oklahoma’s groundwater basins by permitted water users. The resulting figure is considered to be the amount of water that can be safely withdrawn from an aquifer to ensure a minimum basin life of 20 years. The MAY study for the Central Oklahoma aquifer system is to be completed in 2013.