The Owens Lake Dust Mitigation Program is the largest dust mitigation project in the United States. While originally constructed to meet dust mitigation requirements, the Owens Lake Dust Mitigation Program is currently managed in collaboration with multiple partners to meet goals for dust emissions, and efficient water-use, while protecting cultural resources and minimizing impacts to habitat.
Since the early 2000s, LADWP has been funding and implementing the program, successfully reducing dust emissions by 99.4%. The program utilizes EPA-approved dust control methods or Best Available Control Methods (BACMs), including shallow flooding, managed vegetation, gravel, tillage with shallow-flooding backup, and brine with shallow-flooding backup, to contain and prevent dust emissions.
Water Management at Owens Lake
Dust control infrastructure in the Owens Valley is expansive: the program covers approximately 48.6 square miles of lakebed and requires approximately 60,000 acre-feet of water annually. To put those numbers into perspective, 48.6 square miles is roughly the same size as the city of San Francisco and 60,000 acre-feet is enough to supply the entire city of Long Beach, a city of about 462,000 people with water for one year. As regional and state water supplies continue to be stressed by climate change and drought conditions, Owens Lake policymakers and scientists have concluded that to sustainably move forward, dust mitigation must conserve water to the greatest extent possible while maintaining habitat and protecting cultural resources.
Best Available Control Methods
Shallow Flooding accounts for about 60 percent of the overall control measures. LADWP has installed one of the world’s largest shallow flooding systems consisting of a vast network of computer-controlled valves, pipes, outfalls, and sprinklers across the ancient lakebed. Shallow flooding prevents dust emissions by applying water to emissive playa surfaces, suppressing windborne dust. Currently, it is the predominant dust control method on Owens Lake, accounting for approximately 30 square miles of the program area. In order to meet the requirements for dust control within shallow flooding dust control areas, 72% - 75% of the graded surface must be maintained as wet or have saturated soil during the dust season, between mid-October and early July. The saturated surface eliminates dust generation and also traps blowing sand that enters the ponded area.
Brine with Shallow Flooding
Owens Lake is primarily a salt lake with a large brine pool at its center. Brine with shallow flood backup is utilized in shallow flood dust control areas where salinity levels are high enough to create a salt crust that effectively curbs dust emissions. In these areas, 72 -75% of the surface must be covered with salt crust and/or saturated surfaces. Similar to the shallow flooding method, the saturated surfaces eliminate any sand or dust sources while capturing salt particles. The wind-resistant evaporite crust that forms as the standing brine evaporates seals the surface and reduces dust emissions. In some cases, saline shallow flood areas that are unable to meet the brine crust compliance criteria continue to be operated as shallow flood areas. If crust within a brine area breaks down, it is flooded to meet shallow flood wetness criteria, hence the term “back-up.” The stunning reds that paint these brine areas and the brine pool are attributed to salt-loving halobacteria.
Gravel cover is a zero-water-use BACM that involves distributing a layer of gravel on an emissive lakebed to protect it from the wind. Gravel protects the bare ground beneath it against wind erosion by substantially reducing salt and crust formation. Some areas are covered by 4 inches of gravel, while others are covered by 2 inches, underlain with a permanent permeable geotextile fabric to prevent the gravel from settling into the lakebed. The geotextile fabric is a 2.3-mm thick artificial fabric that is permeable to allow for drainage and is resistant to the acids and alkali elements of the soils. To protect the gravel-covered area from flooding, channels and drains are incorporated into the land surrounding the control area.
Tillage with Shallow Flooding Back Up
Tillage is a widely used method for wind erosion control in agricultural and arid regions around the world. It works by roughening the soil surface, reducing wind speed at the surface through the creation of turbulent eddies, which improves resistance to wind erosion. The roughened surface also creates traps to catch windblown soil particles. Installed tillage consists of rows and furrows in roughly east to west directions to create maximum surface roughness against high winds predominantly from the north and south. Where existing infrastructure has allowed, tillage has been installed in a serpentine pattern to provide additional protection from all wind directions. If the regulatory erosion threshold or any of the tillage performance requirements are no longer met, maintenance is performed to restore roughness, or shallow flooding is implemented as a backup control method.
Managed vegetation on the Owens Lake playa is an effective means of preventing and reducing dust as it decreases both sand motion and soil erosion. The aboveground vegetation acts as a windbreak, which lowers wind velocity at the playa surface and consequentially reduces the sand movement that leads to dust emissions. Managed vegetation must, on average, have 37% cover across a dust control area, meet levels of uniformity in vegetation distribution for multi-scale grid tests, and be composed of pre-approved, locally adapted, native plants.
Owens Lake Science Advisory Panel
Established within the 2014 agreement, the Owens Lake Scientific Advisory Panel (OLSAP) reviews scientific issues relating to controlling dust using waterless and low-water use methods, among other related matters. Staffed by the National Academy of Sciences, the panel provides advice on the reduction of airborne dust in the Owens Valley in California.
In 2020, the OLSAP published a consensus study report on the Effectiveness and Impacts of Dust Control Measures for Owens Lake.