Technical Abstract: The picture of water availability across most of the US peanut producing areas is bleak and becoming worse every year. Years of drought and increasing urban drains on water resources are forcing producers to make do with diminishing irrigation stores. The ability of a peanut variety to use water efficiently can spell the difference between high yields or a failed crop when water is limited. High water-use efficiency (WUE), or the ratio of dry matter production to water use, may now become a priority in many peanut breeding programs. We examined the variation in WUE of up to 19 varieties at six US peanut producing areas: Georgia, Florida, North Carolina, Texas, Oklahoma, and New Mexico, by measuring carbon isotope discrimination. It has been well documented that carbon isotope discrimination is an accurate surrogate for WUE in peanut. We also examined WUE variation at a single site in Georgia among three commonly grown varieties under four overhead sprinkler application rates. In both studies, we correlated both specific leaf area and leaf chlorophyll content with carbon isotope discrimination in order to determine if these easy and inexpensive measurements could be indicators of WUE and easily selected for in breeding programs.