Southeastern Florida is underlain by the Biscayne Aquifer, an officially designated “drinking water quality aquifer.” This is the sole source of water for the more than 3.5 million residents of metropolitan Miami-Fort Lauderdale. Due to the unique nature of the soils in southern Dade County, Fla., most agricultural wells for both irrigation and mix-load activities have been exempt from casing and capping requirements. Wells associated with U-Pic stands need to be capped if children are allowed in fields. The county's Dept. of Environmental Resources Management (DERM) began a study of mix-load wells in the late 1980s. They concluded that surface materials, including agrichemicals, could drain directly into the aquifer. This was particularly true in vegetable fields because most are on leased land. In the mid 1990s, a program to develop voluntary guidelines to retrofit these mix-load wells was begun. Several growers met with DERM, the Florida Department of Environmental Protection and Extension, to finalize three basic designs. Extension hosted meetings and reviewed the brochure describing the retrofit program. In 1996, one area came under close scrutiny by the U.S. EPA for potential point-source pollution. These growers were made aware of the program and have retrofitted at least 95% of the wells in the most environmentally sensitive area.