The good sized spring storm that blew into the Eastern Sierra has dropped welcome fresh snow on Mammoth Mountain, but
high winds led to a big dust storm on the Owens Dry Lake.
The City of Los Angeles is closing in on completion of the agreed on dust control measures on the Owens Lake bed, but with winds whipping though the Eastern Sierra on Tuesday, dust levels triggered a Stage 1 Health Advisory in the Southern Owens Valley. At times the highways along the east shore of the lake were closed due to blowing dust.
Ted Schade with Great Basin Unified Air Pollution Control District reports that of the nine dust monitoring stations, seven exceeded the federal PM 10 standard of 150 micrograms per cubic meter. Keeler averaged 953 micrograms per cubic meter over a 24 hour period Tuesday, but there was one hour where the average was over 4000 micrograms per cubic meter.
Sierra Wave’s weather forecaster Dennis Mattinson took PM 10 readings with a portable measuring device a couple of miles outside of Keeler. He reports that he saw many individual readings between 2000 and 8000 micrograms per cubic meter Tuesday morning. At one point, with visibility measured in feet, Mattinson reports that his portable PM 10 meter measured 10,000 micrograms per cubic meter.
In his truck with the windows up and the air on circulate, Mattinson said that his meter still found the air well over the federal standard, so he had to leave because the air was becoming increasingly dangerous to breath.
Schade says the level of PM 10 particulates in the air near Keeler used to routinely run between 5,000 and 10,000 micro grams per cubic meter during dust events ten years ago. Since DWP has cleaned up all but about six square miles of the 45 square miles of lake bed, and Schade says that the dust is not so bad as it was in the past.
The areas that did produce dust on Tuesday were in areas that have not yet been fixed. Some of these areas had been slated for the water reducing moat and row method of dust control, but while Great Basin has signed off on the technique, the State Lands Commission, has not approved the technique.