The Arizona Department of Environmental Quality (ADEQ) amended and added new rules to UST rules in Chapter 12. ADEQ finalized rules: (1) for issuance of no further action (NFA) letters for leaking UST (LUST) sites once the source of contamination has been removed and a corrective action plan has been approved that includes monitored natural attenuation (MNA); (2) to implement the MNA account to be used by ADEQ to continue to monitor LUST sites that have been issued an NFA letter and to perform additional corrective actions if necessary; and (3) allowing ADEQ to close certain groundwater LUST cases where there is an exceedance of the aquifer water quality standards. http://www.azsos.gov/public_services/Register/2007/52/final.pdf pp. 4605-4617.