Water chemistry reconnaissance geochemical modeling in the Meadow Valley Wash area, southern Nevada

Abstract

The study area groundwater system encompasses Coyote Springs, Kane Springs, Moapa and Meadow Valleys. The geology is dominated by Paleozoic carbonates to the north, and younger alluvium and lacustrine deposits to the south. Underflow from Pahranagat Valley mixes with groundwater from Kane Springs Wash and recharge from the Sheep Range to produce the final discharge of Muddy Springs at the head of Moapa Valley. It is possible that at least 4,000 acre- ft/yr of underflow from Meadow Valley Wash contributes to Muddy Spring discharge. The use of BALANCE, WATEQ, and PHREEQE chemically verifies these proposed flowpaths. Volcanic rocks are the probable explanation of sodium-dominated waters in the south. In lower Moapa Valley and Meadow Valley Wash, the Muddy Creek Formation produces saline, generally sodium-sulfate waters (up to 4500 mg/1 TDS) by dissolution of evaporite minerals, primarily gypsum and thenardite. Flow is complex due to local geology and thus geochemical simulation was limited.