AWWA ACE60026

Many drinking water supply watersheds are forested, and forest management over the past century has focused on suppression of forest fires. The watersheds of 3,400 community water systems (CWSs) serving 60 million people in 900 cities are located within National Forest lands. Many of the water supply systems are small, serving a few hundred to a few thousand people, and lack the technical and financial resources to deal with fire impacts on their water supplies on their own. Since 70% of the forest area in the USA is outside of National Forest lands, the number of people relying on forest land for water supplies is much greater. Growing populations at the wildland-urban interface, limited source water supplies, expanding areas of drought, and ever-tightening federal drinking water regulations increase the potential for wildland fires to seriously impact municipal water supplies. Wildland fires like the Hayman and Missionary Ridge fires in Colorado and the Rodeo-Chediski fire in Arizona can have a deleterious impact on water quality in drinking water watersheds. Introductory material in the paper covers the range of pollutants commonly associated with runoff after forest fires, in relationship to MCLs. Most of this pollutant load (>95%) is generally associated with particulate materials. The fate of these particulates in rivers, reservoirs, and water treatment plants is of a significant concern, and affects the longer-term duration impacts of the forest fires on water quality. The focus on organic carbon is of particular importance to the drinking water industry (i.e., DBP precursors, source of non-biologically stable water). Includes 31 references, tables, figures.