Lynn Brandvold, Barbara Popp, and Tianguang Fan, New Mexico Bureau of Geology and Mineral Resources, New Mexico Tech, Socorro, NM.
Wells and springs in the Socorro, New Mexico area have recently been sampled and analyzed for major, minor, and trace constituents. This paper will report on levels of arsenic as well as some selected constituents in these wells and springs. Arsenic in groundwater is an element of interest in New Mexico for several reasons. (1) US EPA is currently considering lowering the maximum contaminant level (MCL) for arsenic in drinking water from 50 mg/L to somewhere between 0.5 and 20 mg/L, or more likely 0.2 to 5 mg/L. (2) Arsenic occurs naturally in groundwater at levels of 10 to 50 mg/L in many parts of the State. (3) Groundwater is used as a source of drinking water for approximately 90% of New Mexicans. Groundwaters in the Socorro area appear to be of two distinct types; a warm temperature, high arsenic type and a low temperature, low arsenic type with some waters an apparent mixture of the two types. Values of arsenic in these waters range from a high of 40 mg/L to less than 2 mg/L.