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The connection between water quality and water quantity is intrinsic and an inherent part of the Total Maximum Daily Load (TMDL) program. Via the Clean Water Act (CWA), Congress directed the Environmental Protection Agency to restore and maintain the chemical, physical, and biological integrity of our nations waters. In 1994, the Supreme Court reiterated that the intent of the CWA is to ensure physical and biological integrity as well as chemical. Instream flows necessary to protect and sustain designated uses are one component of physical integrity.

The CWA also recognizes that the authority of each state to allocate water quantity shall not be impaired by the CWA. The state agency charged with administering the CWA and the state agency charged with managing water quantity are often separated by physical location, organizational structure, customer base, and constituencies. Several states in the arid west recognize it is often impractical if not impossible to improve water quality unless water quantity issues are concurrently addressed. Water quality professionals are attempting to address this issue through TMDL Implementation Plans. Such plans may include: 1) management of existing and new surface water rights and ground water rights where ground water is hydrologically linked to the impaired surface water, through proper metering and reporting; 2) development and realization of effective on-farm conservation measures and best management practices; and 3) development and evaluation of conservation plans for all municipal users in the watershed to ensure waters are conserved and used efficiently.

(The intent of this paper is to discuss the relationship between water quality and quantity in New Mexico related to the creation and implementation of TMDLs. This paper does not represent an official New Mexico Environment Department perspective on the issue of water quality vs. quantity.)