Utah’s Great Salt Lake may turn into a toxic dust bomb. Can a dried-up California lake help stop it?

Peering at the data displayed by one of 13 air-quality monitoring stations scattered across the dried-out expanse that was once Owens Lake, Phillip Kiddoo was impressed. “I’d guess that’s the cleanest air in the country right now.”

The level of PM10 — particulate matter no wider than a fifth or so of a human hair, which can make breathing difficult and worsen heart and lung problems — averaged 4.6 micrograms per cubic meter of air over the previous 24 hours.

Outside the station on a chilly late February day, the...