The Lassen hydrothermal system is in the southern Cascade Range, approximately 70 kilometers east-southeast of Redding, California. The conceptual model of the Lassen system is termed a liquid-dominated hydrothermal system with a parasitic vapor-dominated zone. The essential feature of this model is that steam and steam-heated discharge at relatively high elevations in Lassen Volcanic National Park (LVNP) and liquid discharge with high chloride concentrations at relatively low elevations outside LVNP in the Lassen Known Geothermal Resource Area (KGRA) are both fed by an upflow of high-enthalpy, two-phase fluid within the Park. Liquid flows laterally away from the upflow area towards the areas of high-chloride discharge, and steam rises through a vapor-dominated zone to feed the steam and steam-heated features. The geometric model corresponds to an areally restricted flow regime that connects the Bumpass Hell area in LVNP with regions of chloride hot springs in the Mill Creek canyon in the KGRA south of LVNP. Simulations of thermal fluid withdrawal in the Mill Creek Canyon were carried out in order to determine the effects of such withdrawal on portions of the hydrothermal system within the Park. 19 refs., 17 figs., 4 tabs.

In September of 1981, the Church Universal and Triumphant (CUT) purchased the Malcolm Forbes Ranch, located along the northwest boundary of Yellowstone National Park... On April 17, 1986, CUT drilled a 458-foot well directly across the Yellowstone River from La Duke Hot Spring, just 1.6 miles from the park boundary, for the purpose of intercepting and accessing the La Duke spring flow. They hoped to use this hot water for heating a small number of buildings and filling a hot spring pool (Francis, 1987)... In July 1988, a team from the USGS headed by Geothermal Hydrologist Dr. Mike Sorey met with YNP officials and scientists in order to discuss the 2-year study of the Corwin Springs KGRA -Mammoth Hot Springs area, the stated purpose of which was to determine the potential impacts of geothermal development in the Yellowstone Valley on thermal features in Yellowstone National Park.