A pending environmental issue is the risk of degraded air quality resulting from the proposed water transfer from the Imperial Irrigation District to San Diego. Although exact predictions of resulting air quality are not possible without additional information, initial assessments have concluded that significant exposure of sediments could occur. Both the Imperial and Coachella Valleys are currently in non-attainment for PM10 state standards, a measure of small particles that can be drawn deeply into human lungs, causing respiratory problems.

As inflows are reduced, the Sea’s elevation drops and sediments become exposed. Because the Sea is shallow (comparable to a 40 foot puddle 1/8 of an inch deep), it doesn’t take much drop in elevation to expose a large amount of sediments. If the transfer takes place as proposed without replacing inflows, the Sea will drop over 15 feet and expose almost 70 square miles of sediments.

The amount of dust that would blow depends on a number of factors: the nature of the sediments, the kind of salts that precipitate out in the sediments, the nature of the crust that forms as a result of the salts, the direction and speed of winds, the length of the “fetch” the wind blows across, the availability of larger particles such as sand to disturb the sediments, the amount of other disturbance to the crusts, temperature, and the amount of moisture in the sediments. The potential for blowing dust can be reduced through mitigation – keeping sediments wet, planting saline-tolerant vegetation, and covering emissive soils with gravel.

However, looking at areas such as Owens Lake or Mono Lake, it is clear that mitigation is complicated and expensive. The projected cost for Owens Lake mitigation is roughly $500 million. While sediments around the Sea and other conditions are not expected to be as emissive as Owens Lake, the area of soils exposed may be twice as much. Conditions around the Sea are highly variable and will blow in different places under differing circumstances. If the resulting emissions are only 1 percent of the levels at Owens Valley, it will be enough to exceed PM10 standards, standards that are already being exceeded.