Water for the up-country areas of Maui is supplied through a series of three parallel systems which wrap around Haleakala from north to west. These systems obtain water from the streams in the Waikamoi watershed on the northeast side of the mountain above the road to Hana. The water is transported west around the mountain in pipelines and canals. A map of the three systems is shown on Figure 1. On June 29, 1989, the United States Environmental Protection Agency (EPA) promulgated the Surface Water Treatment Rule (SWTR). The State of Hawaii Department of Health (DOH) has prepared two drafts of the state’s Surface Water Treatment Rule Administrative Manual, the latter dated July 29, 1991. These rules require that public drinking water supplies derived from surface water sources be treated with a process which includes filtration and disinfection. In addition, potable water must comply with the health standards in Chapter 20, Title 11, of the State of Hawaii Administrative Rules. These standards are being revised to reflect current federal EPA standards.