Plan and Design

Assess Soil Suitability
Assess Water Availability & Suitability
Evaluate Vegetation Establishment
Collaborate with Stakeholders
Select Dust Control Measure

The overall goal of the Air Quality Mitigation Program is to keep playa emissions at low levels, even as playa exposure accelerates, through implementation of targeted, proactive dust control measures. This approach provides flexibility for implementing effective dust control measures in the most cost-effective manner. The annual Proactive Dust Control Plan provides recommendations for dust control in priority playa areas identified through the emissions estimates. Once priority playa is identified, dust control measures are determined based on soil suitability, water supply availability, and stakeholder projects.

The Plan and Design steps include:


Assess Soil Suitability

Assess Water Availability & Suitability

Evaluate Vegetation Establishment

Collaborate with Stakeholders

Select Dust Control Measure
Assess Soil Suitability

Dust control planning requires soil information, particularly texture and salinity. In general, soils with finer texture (more silt and clay) are suitable for surface roughening. Dust control measures in areas with coarser texture (more sand) are not suitable for surface roughening. In these areas, vegetation or other physical barriers, such as sand fence and straw bales, are typically selected.


Terrestrial soil sampling on recently exposed playa began in 2016 to evaluate soil texture, characterize soil structure and quality, and develop soil texture maps. Over 1,660 five-foot cores from both terrestrial and sub-aqueous environments have been analyzed to assess soil texture and dust control measure suitability.
Terrestrial soil cores are collected with a Giddings Machine Company direct push soil probe. At each sampling location, intact soil samples are taken to a depth of five feet. Spectroradiometer readings are then collected at five-centimeter intervals to determine soil texture by depth.
Approximately 170 soil cores were collected from the inundated portions of the Salton Sea to support planning as the Sea recedes and playa is exposed.
Soil sampling results demonstrate a wide range of soil texture around the Sea.
Assess Water Availability & Suitability

Surface water resources around the Salton Sea are limited, especially along the western and eastern shores. Groundwater investigations in these areas are currently underway to assess availability and suitability as an irrigation water supply. This is especially important given the emissions potential and sandy soils in these areas.

Surface water resources around the Salton Sea are limited, especially along the western and eastern shores.
IID recently installed seven groundwater wells, including four near Salton City and three near Bombay Beach. The groundwater quality is saline, but suitable for the target species, including Iodine Bush and Big Salt Bush. These species are native, salt-tolerant, and drought-tolerant. Groundwater will be used to support near-term vegetation establishment and expansion as the Sea recedes.
In dust mitigation areas, the goal is to irrigate vegetation until it is mature enough to connect to the near-surface groundwater system. At that point, irrigation water demands are reduced (or no longer required) and available water resources can be re-prioritized. IID is investigating how declining groundwater levels may affect groundwater-dependent vegetation through a Shallow Piezometer Program that includes over 50 groundwater monitoring locations around the Sea.
Evaluate Vegetation Establishment

Vegetation establishment is challenging due to high salinity in playa soils, limited water availability for irrigation, and the desert climate. Iodine bush is the primary species used for dust mitigation due to its high salinity and drought tolerance. Cultivation strategies increase the success of plant establishment. Examples include irrigation to reduce soil salinity, soil amendments to increase plant growth rates, and prevention of seedling sand burial.

Collaborate with Stakeholders

The Salton Sea has and continues to be an important stop-over for millions of migratory birds moving along the Pacific Flyway. As the transfer of conserved water ramps up, increased salinity is and will continue to accelerate changes to the food web, significantly reducing the quality and availability of habitat for these migratory birds. IID and other stakeholders are targeting critical habitat creation and enhancement projects to minimize impacts to migratory birds and other important waterfowl, and to provide air quality benefits by protecting the playa surface. For example, the California Natural Resources Agency, the California Department of Water Resources and the California Department of Fish and Wildlife are implementing the Salton Sea Management Program (SSMP), which includes a 10-year plan to construct 30,000 acres of habitat and dust suppression projects around the Sea. In addition, the National Audubon Society is working to stabilize and enhance 250 acres of emerging wetlands near the town of Bombay Beach.

Select Dust Control Measure

Dust control measures are selected based on soil texture and available water resources.

Surface roughening is an especially valuable dust control measure as the western United States continues to experience historic drought conditions, with no relief in sight, and an associated pressure on increasingly limited water resources.

Surface Roughening Vegetation Surface Roughening with Vegetation Non-Erodible Elements

 

Surface roughening provides quick, waterless, and effective control on exposed playa by decreasing the wind velocity at the surface and by physically trapping soil particles from upwind sources.

Salt- and drought-tolerant vegetation stabilizes the surface and suppresses soil and sand movement beneath and on the leeward side of its canopy. Iodine bush is the primary species used due to its high salinity tolerance.

Surface roughening with vegetation reduces the wind velocity at the soil surface. Surface roughening aids in vegetation establishment by limiting abrasion from sand motion and burial of young plants.

Non-erodible elements (physical barriers) provide surface roughness and control dust by the same mechanisms as surface roughening and vegetation. The degree of erosion control achieved depends on the dimensions, configuration, density, stiffness, and porosity of the barriers. Examples include sand fences and bales.