The Aug 24, 1996 Earth Week column in the San Francisco Chronicle reported that:
Three dairy cows in New Zealand's Atiamuri area died from a toxic level of fluorine after grazing on pasture covered in volcanic ash from recent eruptions of Mount Ruapehu. Another animal had to be destroyed after it was discovered that it too had ingested ash-laden fodder. Ruapehu has remained relatively quiet in recent weeks.
Excerpts from a December 15, 1997 Associated Press article called
Volcanic Eruption in Sierra would Jeopardize LA Water
LOS ANGELES (AP) - After recent swarms of earthquake tremors in Los Angeles' main watershed, authorities are worried about what would happen to the city water supply if a volcano were to erupt. A magnitude-4.9 earthquake struck the Mammoth Lakes area Nov. 30 - the strongest of thousands of quakes since the summer ...
However, Department of Water and Power geologists recommended last week that the agency update its plan for dealing with a possible eruption in the Mammoth Lakes area. Two-thirds of all water used in Los Angeles comes from a network of streams, reservoirs and aqueducts that stretches for hundreds of miles down the eastern Sierra Nevada through the remote Mammoth Lakes area. The earthquakes are believed to be caused by moving magma, or molten rock, fracturing rock or pressurizing liquid roughly four miles beneath the surface, which has risen more than 2 feet in places over the past 18 years. ...
Seismic activity in the area already causes water quality problems, introducing arsenic and other chemicals into the water supply. Extensive treatment is required to reduce the level of the toxic element in the city's drinking water.