Hot Creek, CA

Hot Creek is a stream in Mono County, California, United States. It begins its course as Mammoth Creek, originating in lakes above the town of Mammoth Lakes, California, just south of Mammoth Mountain. The stream water is derived primarily from melting snow as it leaves Twin Lakes, 8,500 feet (2,600 m) above sea level. It is quite cold, rarely above 50 °F (10 °C). As Mammoth Creek flows into the Long Valley Caldera, it is joined by warmer water from thermal springs in the Hot Creek State Fish Hatchery. From this point on, the stream is named Hot Creek even though water temperature seldom exceeds 68 °F (20 °C) until it reaches Hot Creek Gorge.

In the Hot Creek Gorge, 8 miles (13 km) east of the town of Mammoth Lakes, numerous hot springs flow into a snowmelt-fed stream. The area is managed by the United States Forest Service as a geologic interpretive site and has been a popular recreational area for fishing, swimming, hiking, bird watching, and photography. The United States Geological Survey (USGS) has long monitored spring activity, water temperatures and chemistry, and stream flow.

Hot Creek also harbors danger. The locations, discharge rates, and temperatures of springs often change. The larger and more vigorous springs discharge from fractures in the volcanic rock (altered rhyolite) in the gorge. When fractures become sealed by mineral deposition, spring discharge and temperature decline. When new fractures develop or sealed fractures reopen, spring discharge and temperatures can increase suddenly. Rock fracturing happens because the thermal area lies within a region of frequent earthquakes and active uplift (deformation) of the ground. The changes in the locations and vigor of springs can be sudden and dangerous to unprepared visitors, especially if they stray beyond walkways and fences. Since May 2006, springs in and near the most popular swimming areas have been geysering or intermittently spurting very hot, sediment-laden water as high as 6 feet (2 m) above the stream surface. At times this geysering activity is vigorous enough to produce “popping” sounds audible from hundreds of feet away. The geysering usually lasts a few seconds and occurs at irregular intervals, with several minutes between eruptions. The unpredictability of this hazardous spring activity led the U.S. Forest Service to close parts of the Hot Creek Gorge in June 2006.