Samples for water chemistry analysis were filtered to 0.45 µm upon collection. Since the solute-rich samples continued to form precipitates, samples were filtered again immediately prior to analysis if needed. All samples were very rich in solutes and were analyzed at multiple dilutions (1:100 to 1:1000) to match instrument measurement ranges for various analytes. Water chemistry analyses were performed at the U.S. Geological Survey laboratories in Menlo Park, California. The concentrations of fluoride (F-), chloride (Cl-), sulfate (SO42-), and bromide (Br-) in samples were determined by ion chromatography with a Dionex ICS-2000, using a 250 mm Dionex IonPac AS18 column. The concentrations of major cations were determined via inductively coupled plasma-optical emission spectrometry (ICP-OES) using a ThermoScientific ICAP 6500 Duo. A mixed-element standard (produced to spec by High-Purity Standards Inc.) was run at a range of dilutions to calibrate the instrument. Additional cation concentrations, including heavier trace elements, were determined by inductively coupled plasma mass spectrometry (ICPMS, NExION 300Q, Perkin Elmer) using a method adapted from Garbarino and Taylor (1996). External standards, serially diluted from ultrapure, single-element stock, were used to create calibration curves. References: Garbarino, J.R. and Taylor, H.E., 1996. Inductively coupled plasma-mass spectrometric method for the determination of dissolved trace elements in natural water. Washington, DC: US Geological Survey. USGS OFR 94-358, 49 p. https://doi.org/10.3133/ofr94358