Effectiveness and Impacts of Dust Control Measures for Owens Lake (2020) / Chapter Skim
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On average since 2007, water use for dust control required 31 percent of LADWP's fresh water supplies available at Owens Lake, 2 with a range of 17 to 51 percent. In 2014, a Stipulated Judgment agreed to by LADWP and the District3 ended litigation concerning dust control requirements and acknowledged the need "for additional effective DCMs that do not rely on water that can be substituted in areas currently under control or applied in areas ordered to be controlled." The Judgment also acknowledged "the need to 1 Prior to LADWP's launch of dust mitigation projects in 2000, the District conducted research and testing of DCMs in the 1980s and 1990s.
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The request to establish OLSAP is pursuant to a Stipulated Judgment that LADWP and GBUAPCD entered into in 2014.a The National Academies will establish, staff, and administer OLSAP according to institutional poli cies and procedures. As indicated in the 2014 Stipulated Judgment, OLSAP's first task will be to evaluate the ef fectiveness of alternative dust control methodologies for their degree of PM10 reduction at the Owens Lake bed and to reduce use of water in controlling dust emissions from the dried lakebeds.
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a The District, in concurrence with the U.S. Environmental Protection Agency, determines dust control measures to be BACMs for use on Owens Lake (see Chapter 4 for more discussion of current BACMs)
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OVERALL CONCLUSION DCMs applied at Owens Lake during the past 20 years have significantly reduced PM10 concentrations in the Owens Valley, although further progress in controlling dust is needed to meet air quality standards. The panel evaluated 15 DCMs based on their potential effectiveness in reducing PM10 emissions, water use, and environmental impacts.
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continue to challenge the ability to attain the PM10 air quality standards within the Owens Valley Planning Area (the southern Owens Valley, where Owens Lake is situated)
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While management of habitats across broad regions will become more challenging under climate change because of habitat loss and effects on breeding and food availability, the habitats provided by Owens Lake will become more critical to local and regional conservation, particularly because saline lake bird habitat elsewhere within the Great Basin is shrinking. In fact, Great Basin shorebird populations have already decreased by 70 percent over the past few decades.
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Specific research topics to inform future decision making at Owens Lake are provided in Chapter 4 and include the following: • Strategies for long-term salinity management in shallow flooding and managed vegetation DCMs, including the capacity to maintain target salinities over time; • Minimum percent coverage needed for alternative vegetation species and mixtures of species as DCMs with the potential to reduce irrigation requirements, and how site-specific conditions on the lakebed impact the performance, durability, and management requirements; • Potential for dynamic precision surface wetting to provide effective control in real-time that reduces water use; • Approaches for enhancing the formation of salt crusts and their long-term stability under a range of conditions; • Performance and feasibility of cobbles and natural and artificial porous roughness as DCMs on the lakebed and their potential to provide additional vegetated habitat; 7
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PM10 emission rates from individual dust control areas on the Owens Lake bed are estimated using sand flux measurements.5 DCMs that are highly effective in reducing horizontal sediment transport are also effective in significantly reducing airborne PM10 concentrations. However, the relationship between PM10 emissions and sand flux is highly variable in space and time, depending on the type and condition of the surface from which PM10 is emitted and meteorological conditions.
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Recommendation 2: The District and LADWP should develop and apply additional methods to quantify, with uncertainty estimates, PM10 emissions from individual dust control areas, based on direct measurements of airborne PM10 concentrations. All devices should be calibrated and tested for representative operation under the field conditions encountered on and around the Owens Lake bed.
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In addition, use of PM10 emission estimates may enable hybrid approaches, such as developing vegetative cover on shallow flooding water management areas, and adaptive response, such as adding roughness elements to vegetative cover areas experiencing temporary declines. One disadvantage of relying on control area–specific estimates of PM10 emissions, based on airborne PM10 concentration, is the difficulty in assessing compliance under low to moderate wind conditions.
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There is a need to place hybrid or new DCMs in more site-appropriate locations that account for the multifaceted characteristics of the Owens Valley and its environs as an interconnected system. The complex challenge to meeting the multiple goals related to managing PM10 in Owens Lake can be addressed through a landscape-based, systems approach that is flexible and adaptive.
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Through its upcoming activities, the panel could provide valuable advice on implementing the recommendations in this report, especially those regarding the use of PM10 concentration measurements to quantify emissions from control areas and the application of landscape-based, systems approaches to assess dust control configurations at Owens Lake.
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