Vegetation Establishment to Promote Dust Control Using Natural Physical Barriers and Surface Hydrology at the Salton Sea, CA; Chris Sanderson

Vegetation Establishment to Promote Dust Control Using Natural Physical Barriers and Surface Hydrology at the Salton Sea, CA

Ondrea Hummel¹, Chris Sanderson¹ , Sujoy Roy¹, Jacob Kollen²

¹Tetra Tech; Ondrea.Hummel@tetratech.com, chris.sanderson@tetratech.com, sujoy.roy@tetratech.com,. ² California Department of Water Resources; jacob.kollen@water.ca.gov.

The Salton Sea is a hypersaline inland lake situated in the Imperial Valley of Southern California. Over the past 20 years the lake surface elevation has decreased by approximately 12 ft, exposing the dry lakebed (playa) and accumulated lakebed sediments containing metals, salts and likely a suite of degradation products resulting from chemicals used in production agriculture. The ongoing recession of the lake and subsequent exposure of the dry lakebed poses potentially significant air quality problems for the nearby population as well as the region in general. The lake surface elevation is expected to drop another 18 feet over the next 20 years (CH2M Hill, 2018), thus exposing an additional 80,000 acres of lakebed. If no action is taken, the increase in exposed lakebed is anticipated to contribute to an increase in wind-blown dust (PM₁₀) and exacerbate a regional air quality problem.

A multi-disciplinary team led by the California Department of Water Resources, along with Tetra Tech, is designing a landscape-scale dust suppression and vegetation enhancement project over 2,500 acres. The primary aim of this plan is to prevent dust emissions through roughness-based dust control methods. This initial planning effort has consisted of a review of plant establishment challenges on the playa, specifically aeolian transport processes, climatic and hydrologic factors, and edaphic and vegetative parameters associated with plant establishment. Roughness-based dust control consists of the construction of natural physical structures and establishment of Allenrolfea occidentalis, a keystone species in hyper-xeric halophytic settings. Ephemeral surface water inputs from surrounding watersheds are proposed to be utilized using physical structures consisting of shallow berms, furrows, compost socks, and other surface contouring built in key landscape positions in order to retain stormwater flows on site and promote vegetation germination and establishment. The selection and rationale for structures and placement will be presented along with the modeling efforts and field data collection activities.