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Dry beds at Lake Owens were the main source of dust in the Owens Valley, but mitigation efforts have reduced these emissions to the point that other sources of dust in the surrounding desert cause most of the poor air quality days in the area.
Lake Owens was left dry after Los Angeles began smashing the East Sierra Basin over a century ago for its own needs. However, as LA Water and Power Department has taken mitigation measures such as spreading water over parts of the lake bottom, the amount of dust from lake beds has been decreasing in recent years.
“We’re a great leader in our efforts to help people understand how we’re doing,” said Ted Russell, professor of civil and environmental engineering at Georgia Tech and chairman of the Owens Lake Scientific Advisory Committee. “We want to be able to understand where these sources are, so we’ll have better control over them.”
Founded in 2018 by the National Academy of Science, Engineering and Medicine, the panel released this week a report detailing research and data on particulate matters that can penetrate the lungs and cause health problems.
The team said in the report that important dust sources in the area around the lake included land that left floods with sand and debris, Keeler Dunes, Olancha Dunes, alluvial fans and areas where soil was hampered due to road infrastructure.
Scientists say some of these areas are naturally sources of dust, while others are releasing more of it due to water detours and changes in the landscape by people.
Russell said DWP’s dust control efforts have been successful in reducing PM10 emissions from lake beds and reducing the frequency of overruns of air quality standards.
DWP invested approximately $2.5 billion in dust mitigation projects in arid lake beds using methods that include shallow flooding at the bottom of the lake, gravel arrangement, and planting vegetation that ravaged the soil and acted as windbreaks.
Russell said that air quality processes caused by non-lake sources have been rising and falling in recent years, with some days rising without a clear trend.
“The external sources of this arid environment of lakes are important and are currently promoting much of the PM10 excess,” Russell said. He said that means achieving the region with national air quality standards.
The report is sponsored by the DWP and the Great Basin Unified Air Pollution Control District, and regulates air pollution in areas of approximately 32,000 people.
DWP did not immediately comment on the panel’s findings.
Scientists noted that on the northeastern side of Lake Owens, Keeler Dunes had shifted from the “mainly vegetation dune system” to something that emits more dust in the last century. They wrote that “increased sand transport after the water detour from Lake Owens made Keeler sand dunes unstable.”
Scientists said that ongoing efforts to stabilize the Keeler Dunes are effective in reducing dust. The pieces there included arranging straw les on the sand. This allowed the native shrub to start rooting and holding back the dust that was blown away.
The panel said that other efforts to establish these and native vegetation retain the promise to control dust in other regions and further improve the air quality of Owens Valley.
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