"After massive surface water diversions by the Los Angeles Department of Water and Power, including the diversion of the Owens River to the Los Angeles Aqueduct in 1913, dropping water levels in the Owens Lake exposed toxic sediments in the lake bed. The lake became the single largest source of particulate matter air pollution in the United States."
"Studies of dust transport from Owens Lake show that the standard can be exceeded more than 50 miles away and expose many more people to violations of the PM-10 standard than just the residents near Owens Lake."
The dry Owens Lakebed today is the largest single source of particulate matter (dust) in the United States.
For more information about what happened in the infamous Owens Valley, CA water grab: