By establishing the District, the Arizona State Legislature created an entity charged with keeping county residents safe from flood hazards and established an independent funding source for essential projects. The District is a municipal corporation and political subdivision of the State of Arizona. The Maricopa County Board of Supervisors doubles as the District's Board of Directors and receives counsel from the Flood Control Advisory Board comprised of county citizens.

The 2009 Comprehensive Floodplain Management Plan and Program is intended to be used as a general guide for future decision-making in District activities. The Plan aims to present adequate background information to aid District staff in prioritizing areas for future studies and projects. The Plan identifies historic flooding events, reviews the District's efforts to solve flooding problems, and formulates five-year plans to reduce flooding through flood control project construction, floodplain identification, and planning programs throughout the county.

In September 2005, some concerned Walker residents contacted the Arizona Department of Health Services in regards to the quality of groundwater in the area. The residents petitioned ADHS to perform well water tests to determine the character of the water, and whether there is any potential health risk associated with consuming or using the water. In response to the concerned community members and in agreement with the Agency for Toxic Substances and Disease Registry, ADHS collected water samples from the site and completed a health consultation. This health consultation evaluates if the levels of lead and other metals in the private wells in Walker area pose any adverse health effects.

This report evaluates the potential exposure pathways associated with vermiculite concentrate processing activities at the Ari-Zonolite facility. The site is located in the near downtown area of Glendale, approximately ½ mile from the city hall, downtown shops, and other buildings. The former Ari-Zonolite facility received vermiculite from the Libby, Montana, mine. From 1951 to 1964, the site was leased the site to the Ari-Zonolite Company. Following the removal of the vermiculite concentrate processing equipment in 1964, several businesses have occupied the site. None of these businesses were involved in vermiculite processing activities. The last occupant of the former vermiculite processing building was an automotive restoration business, which vacated the site in 2002.

The W.R. Grace facility in Phoenix, Arizona, received vermiculite concentrate from the Libby, Montana, vermiculite mine. W.R. Grace Company has owned and operated the Arizona site since 1964. In 1964 W.R. Grace purchased the company that had previously occupied the site and, following the relocation of its vermiculite exfoliation furnace from Glendale, Arizona, began processing vermiculite concentrate and marketing it under the Zonolite® brand. The objective of this health consultation is to evaluate exposure pathways and potential health effects in those persons who, between 1964 and 2002, may have been exposed to Libby asbestos as a result of vermiculite concentrate processing activities and waste materials from the W.R. Grace exfoliation facility in Phoenix.

The Arizona Department of Health Services reviewed existing data and performed a health consultation to evaluate the potentially adverse health effects due to VOCs created by air emissions from the Miller Road Treatment Facility. Prior to the existence of our current environmental regulations, local industries improperly disposed of organic solvents directly onto the ground or into dry wells. This subsequently contaminated all three levels of the aquifer.