The Pinto Creek watershed contains areas of known natural copper mineralization that have been exploited by past and present mining activities. These activities have created point and non-point pollution sources that potentially contribute copper to the creek and its tributaries. Natural mineralization also contributes copper loadings to the basin. Pinto Creek has been listed by the State of Arizona under Section 303(d) of the Clean Water Act for non-attainment of the water quality standard for dissolved copper. Consequently, the U.S. Environmental Protection Agency (EPA), with the support of the Arizona Department of Environmental Quality (ADEQ), is establishing this Total Daily Maximum Load (TMDL) to address this non-attainment. This document describes the TMDL, supporting analysis, and information compiled and analyzed to develop the TMDL, including: applicable water quality standards, available water quality data, calculation methods, legal and policy considerations, and implementation mechanisms.