Geothermal activity along Hot Creek
south and east of Mammoth Lakes has been causing water ,quality problems for years by
introducing arsenic and other chemicals into the water supply. exstensive treatment is
required at several points downstream to reduce the level of the toxic element in the
city's drinking water. Despite mounting evidence of seismic unrest and volcanic precursors
in the area. including a more than 2-foot rise in the earth's surface during the past 18
years, it was only last week that DWP geologists recommended forming a committee to update
the department's contingency plan "in regards to this ongoing threat of a volcanic
In fact, Assistant General Manager James
F. Wickser acknowledged that the DWP's emergeney plan for the Owens Valley anticipates a
major earthquake. but not a volcanic event He promised that the plan will be revised.
"Clearly the volcanic threat was not on the horizon in the
early 1970s," said Wickser, who is in charge of the city's water system. "It
could have dramatic effects, far more pronounced than an earthquake."
After a magnitude 4.9 earthquake struck the Mammoth Lakes area
Nov. 30-the strongest of thousands of quakes since the summer-U.S. Geological Survey
scientists came close to "yellow volcano watch" for the region.
Such a watch is the second level on a four-step, color-coded
system designed to alert the public and government agencies of changing conditions and
hazards leading to a volcanic eruption.