Ephemeral lakes (playas) at the termination of drainages are a common feature of drylands. When dry, playa sediments can be highly wind-erodible, becoming potent local and regional sources of dust and PM 10 , airborne particles with diameters less than 10 µm, causing potentially sudden loss of visibility to travelers on downwind roadways. Lordsburg Playa, in southwestern New Mexico, USA is bisected by Interstate Highway 10. Dust storms emanating from the playa have been responsible for numerous visibility-related road closures (including 39 road closures between 2012- 2019) causing major economic losses, as well as hundreds of dust-related vehicle crashes, causing 41 lost lives in the last 53 years. We investigated the critical wind friction velocity thresholds and the dust emissivities of surfaces representing areas typical of Lordsburg Playa’s stream deltas, shorelines, and ephemerally flooded lakebed using a Portable In-Situ Wind ERosion Laboratory (PI-SWERL). Mean threshold friction velocities for PM 10 entrainment ranged from less than 0.30 m s -1 for areas in the delta and shoreline to greater than 0.55 m s -1 for ephemerally flooded areas of the lakebed. Similarly, we quantified mean PM 10 vertical flux rates ranging from less than 500 µ g m -2 s -1 for ephemerally flooded areas of lakebed to nearly 25,000 µg m -2 s -1 for disturbed delta surfaces. The apparently unlimited PM 10 supply of the relatively coarse sediments along the western shoreline however is problematic and indicates that this may be the source area for longer-term visibility limiting dust events and should be a focus area for dust mitigation efforts.

In drylands around the world, ephemeral lakes (playas) are common. Dry, wind-erodible playa sediments are potent local and regional sources of dust and PM10 (airborne particles with diameters less than 10 µm). Dust clouds often cause sudden and/or prolonged loss of visibility to travelers on downwind roadways. Lordsburg Playa, in southwestern New Mexico, USA is bisected by Interstate Highway 10. Dust storms emanating from the playa have been responsible for numerous visibility-related road closures (including 39 road closures between 2012-2019) causing major economic losses, in addition to well over a hundred dust-related vehicle crashes causing at least 41 lost lives in the last 53 years. In order to improve understanding of the surfaces responsible for the dust emissions, we investigated the critical wind friction velocity thresholds and the dust emissivities of surfaces representing areas typical of Lordsburg Playa’s stream deltas, shorelines, and ephemerally flooded lakebed using a Portable In-Situ Wind ERosion Laboratory (PI-SWERL). Mean threshold friction velocities for PM10 entrainment ranged from less than 0.30 m s-1 for areas in the delta and shoreline to greater than 0.55 m s-1 for ephemerally flooded areas of the lakebed. Similarly, we quantified mean PM10 vertical flux rates ranging from less than 500 µg m-2 s-1 for ephemerally flooded areas of lakebed to nearly 25,000 µg m-2 s-1 for disturbed delta surfaces. The unlimited PM10 supply of the relatively coarse sediments along the western shoreline is problematic and indicates that this may be the source area for longer-term visibility reducing dust events and should be a focus area for dust mitigation efforts.

Ephemeral lakes (playas) at the termination of drainages are a common feature of drylands. When dry, playa sediments can be highly wind-erodible, becoming potent local and regional sources of dust and PM 10 , airborne particles with diameters less than 10 µm, causing potentially sudden loss of visibility to travelers on downwind roadways. Lordsburg Playa, in southwestern New Mexico, USA is bisected by Interstate Highway 10. Dust storms emanating from the playa have been responsible for numerous visibility-related road closures (including 39 road closures between 2012- 2019) causing major economic losses, as well as hundreds of dust-related vehicle crashes, causing 41 lost lives in the last 53 years. We investigated the critical wind friction velocity thresholds and the dust emissivities of surfaces representing areas typical of Lordsburg Playa’s stream deltas, shorelines, and ephemerally flooded lakebed using a Portable In-Situ Wind ERosion Laboratory (PI-SWERL). Mean threshold friction velocities for PM 10 entrainment ranged from less than 0.30 m s -1 for areas in the delta and shoreline to greater than 0.55 m s -1 for ephemerally flooded areas of the lakebed. Similarly, we quantified mean PM 10 vertical flux rates ranging from less than 500 µ g m -2 s -1 for ephemerally flooded areas of lakebed to nearly 25,000 µg m -2 s -1 for disturbed delta surfaces. The apparently unlimited PM 10 supply of the relatively coarse sediments along the western shoreline however is problematic and indicates that this may be the source area for longer-term visibility limiting dust events and should be a focus area for dust mitigation efforts.