- Air Monitoring Network
- Air Quality Plans
Overview of Great Basin Air Pollution Control District Air Quality Plans
Coso Junction PM10 Planning Area State Implementation Plan
Novenber 1, 2004 - State Implementation Plan for the Coso Junction PM10 Planning Area
The Mono Basin Planning Area experiences severe episodes of air pollution attributable to windblown erosion of fine particulate matter, known as PM10, from the exposed lake shore of Mono Lake--the water elevation of the lake having declined approximately 45 feet between 1941 and 1989, due to water diversions from tributary streams by the City of Los Angeles Department of Water and Power. These pollution episodes produce concentrations of PM10 that violate federal, health-based air quality standards and adversely impact the public trust resources of the Mono Basin.
The present document summarizes the air pollution problem and its projected resolution, including: a synopsis of the regulatory status, a description of the planning area, an inventory and analysis of the sources and severity of polluting emissions, and the impact on human health and natural resources, a presentation of modeling results that predict the distribution and concentration of emissions at varying lake levels, and a demonstration of attainment through implementation of the control measure--a gradual restoration of the lake level to an elevation of at least 6,391 feet.
The SIP includes detailed analyses of the sources of PM-10, their contributions and impacts, the effects of population growth on future PM-10 levels and the effectiveness of controls to attain and maintain the PM-10 Federal Standard. The PM-10 air quality data that was used for the analyses is discussed in Section 2.0. The data summary includes analyses of pollution episodes, trends and meteorological conditions. The PM-10 emissions inventory is included in Section 3. This section includes a discussion of the methods and assumptions used to calculate the emissions for wood stoves, fireplaces, vehicle exhaust, resuspended road dust and cinders, as well as industrial point sources. A Chemical Mass Balance (CMB) Model was run to estimate the contributions from from different PM-10 source types to the ambient PM-10 concentrations on peak days. Section 4 includes the analyses of the contributions from wood burning, road dust and cinders, and vehicle exhaust to the ambient PM-10 concentrations. The effects of population growth on the air quality are discussed in Section 5. This section considers the effects of increased numbers of visitors, residents and vehicle traffic on the PM-10 concentrations over the next 15 years. The particulate matter regulations that were adopted by the Town of Mammoth Lakes are included in Section 6. The final control strategy and the demonstration of the attainment with the PM-10 Standard is summarized in this section. A detailed analysis of the numerical calculations is included in Appendix I.
Air quality monitoring by the District has shown that the bed of Owens Lake is the major source of PM10 emissions contributing to air quality violations in the Owens Valley Planning Area. In January 1993, the southern Owens Valley was reclassified as a “serious nonattainment” area for PM10.
Studies of dust transport from Owens Lake show that the standard can be exceeded more than 50 miles away and expose many more people to violations of the PM10 standard than just the residents near Owens Lake. The dust from Owens Lake at concentrations that can be above the federal PM10 standard annually affects about 40,000 permanent residents between Ridgecrest and Bishop. In addition, many visitors spend time in the dust-impacted area to enjoy the many recreational opportunities the Eastern Sierra and high desert have to offer. Wind speeds greater than about 17 mph (7.6 m/s) have the potential to cause wind erosion from the barren lake bed. Ambient PM10 readings in the Owens Valley Planning Area are the highest measured in the country.
The City of Los Angeles, acting through its Department of Water and Power (LADWP) is responsible for installing and operating the dust control measures on Owens Lake. Water diversions by the LADWP since early in the 20th century have cut Owens Lake off from its natural sources of water and caused the saline lake bed to be exposed. Frequent winds in the Owens Valley loft the lake bed soils and cause the PM10 violations. The 1998 SIP required the LADWP to begin operation of dust control measures by the end of 2001.
The 2008 State Implementation Plan (2008 SIP) has been prepared by the Great Basin Unified Air Pollution Control District in response to a finding by the United States Environmental Protection Agency (USEPA) that the Owens Valley Planning Area did not attain the 24-hour National Ambient Air Quality Standard (NAAQS) for particulate matter of 10 microns or less (PM10) by December 31, 2006, as mandated by the Clean Air Act Amendments of 1990 (CAAA). This document includes an analysis of the particulate matter air pollution problem in the Owens Valley and provides a revised control strategy to bring the area into attainment with the federal air quality standard for particulate matter, as soon as practicable by achieving at least a 5 percent reduction in PM10 emissions per year. The 2008 SIP must demonstrate that the NAAQS can be attained by March 23, 2012, unless the USEPA grants an extension which could make the deadline March 23, 2017 (CAAA §179(d)(3)). The 2008 SIP also incorporates provisions of the 2006 Settlement Agreement between the District and the City of Los Angeles Department of Water & Power (City) to expand dust control measures to additional areas at Owens Lake in order to attain the NAAQS as soon as practicable.