Hot Creek (Mono County, California)

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, Convert|8500|ft|m|-2 above sea level. It is quite cold, rarely above Convert|50|F|C|0. 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 thoughwater temperature seldom exceeds Convert|68|F|C|0 until it reaches Hot Creek Gorge.cite web|url=http://www.fs.fed.us/geology/Hot%20Creek.pdf|title=Boiling Water at Hot Creek|work=Our Volcanic Public Lands|publisher=USGS and USFS|accessdate=2007-09-16]

In the Hot Creek Gorge, Convert|8|mi|km|0 east of the town of Mammoth Lakes, numerous hotsprings 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.

The springs near Hot Creek host one of the two known populations of the endangered Owens Tui Chub. [cite web|url=http://www.fs.fed.us/r5/snfpa/final-seis/biological-documents/BO/III/2.htm|title=Owens Tui Chub|work=Biological Opinion for SNFPA SEIS Final|publisher=USFS|date=2003-07-30] It was also used as a location in the movie True Grit.

Why is Hot Creek hot?

In hydrothermal systems the circulation of ground water is driven by a combination of topography and heat sources. The system in Long Valley Caldera is recharged primarily from snowmelt in the highlands around the western and southern rims of the caldera. The meltwater infiltrates to depths of a few kilometers, where some is heated to at least Convert|430|F|C|-1 by hot rock near cooling magma beneath the Inyo craters and domes, Convert|10|mi|km|0 west of Hot Creek. The heated water, kept from boiling by high pressure, still has lower density than cold water, and it rises along steeply inclined fractures to depths of 0.3-1.25 miles (0.5-2 km). It then flows eastward through rock layers to discharge points at the surface along Hot Creek and around Crowley Lake. The water temperature declines eastward because of heat loss and mixing with cold water, and in the springs near Crowley Lake temperatures are at only about Convert|125|F|C|-1.The springs in Hot Creek all emerge along a stream section between two faults and dischargea total of about 8.5 cubic feet per second (about 240 liters per second) of hot water.This water flow represents nearly 70 percent of the total heat discharged by all thermalsprings in Long Valley Caldera. The thermal springs farther east all discharge less waterand at lower temperatures.

Recent danger

Hot Creek also harbors danger. The locations, discharge rates, and temperatures of springsoften change. The larger and more vigorous springs discharge from fractures in thevolcanic rock (altered rhyolite) in the gorge. When fractures become sealed by mineraldeposition, spring discharge and temperature decline. When new fractures developor 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 theystray 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 Convert|6|ft|m|0 above the stream surface. At times this geysering activity is vigorous enough to produce “popping” sounds audible from hundreds of feet away. The geysering usuallylasts 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 toclose parts of the Hot Creek Gorge in June 2006 [cite web|url=http://www.fs.fed.us/r5/inyo/news/2006/07/nr_hot_creek.shtml|title=New Activity at Hot Creek Geologic Site|accessdate=2007-05-05 Inyo National Forest Press Release] , and the closure has remained ineffect as of spring 2008.

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