Water-quality investigation near the Chico and Hunters geothermal lease-application areas, Park and Sweet Grass counties, Montana

Water quality in and adjacent to geothermal lease-application areas near Chico and Hunters Hot Springs was investigated during two surveys in October 1976 and April 1977. The resulting data were needed to evaluate the effects of proposed geothermal exploration and development on the Yellowstone River and its tributaries.

Waters from the two hot springs, the Yellowstone River, and its tributaries that drain the proposed lease areas are generally suitable for drinking, except for excessive concentrations of fluoride and hydrogen sulfide in waters from Hunters Hot Springs. The water from Chico Hot Springs is suitable for irrigation, but the water from Hunters Hot Springs presents a very high sodium and a medium salinity hazard and is generally unsatisfactory for irrigation.

The effect of the thermal waters on streamflow and chemical discharge of the Yellowstone River during the surveys was negligible and less than the accepted error of measurement. Production of higher volumes of more concentrated water can be expected to accompany testing and development of the geothermal resource.