Great Basin Unified Air Pollution Control District Background

Eastern Sierra being engulfed by wind blown dust from Owens Lake, South of Big Pine, Inyo County.  Photo: Phill Kiddoo

History and Purpose

California law requires all counties to have or belong to an Air Pollution Control District (APCD). There are 35 districts in California: 4 partial-county districts, 21 single-county districts and 10 multi-county districts. Inyo, Mono and Alpine Counties joined together in 1974 in a joint powers agreement to form the Great Basin Unified APCD, which covers the whole Great Basin Valleys Air Basin. The total size of the District is 13,975 square miles or almost 9 million acres. Our District population is about 32,000 people. The Governing Board is made up of two supervisors from each of the three member counties, plus one town councilman from the Town of Mammoth Lakes. State law also allows the City of Bishop to have a member on the Board; however, the City has chosen not to seat a representative.

The purpose of an APCD is to enforce Federal, State and local air quality regulations and to ensure that the federal and state air quality standards are met. These standards are set to protect the health of sensitive individuals by restricting how much pollution is allowed in the air. To meet these standards we enforce those federal laws delegated to us, state laws on stationary (as opposed to mobile) sources of pollution, and pass and enforce our own regulations as they become necessary. The District does not generally regulate mobile air pollution sources (cars and trucks)—that is the responsibility of the California Air Resources Board (CARB).

California is the only state with local APCDs. Local control allows us to tailor our regulations to our problems. For example, Los Angeles needs many very strict regulations on ozone production to control their smog problem; Great Basin does not have an ozone problem, so we do not have those regulations. On the other hand, we have problems with woodsmoke in Mammoth Lakes, so we have regulations just in the Town of Mammoth Lakes that are stricter than many other regions of California.


The District has three arms with different functions: the Governing Board, the Hearing Board and the Air Pollution Control Officer. The Governing Board (Board) is a legislative body that adopts the rules and regulations under which we operate. A copy of these rules and regulations are attached for new Board members. The Hearing Board is a quasi-judicial body that hears appeals from decisions of the APCO and grants temporary variances from District Rules and Regulations. The Air Pollution Control Officer (APCO) is the executive, who enforces the rules and regulations passed by the Board, and also parts of the State Health and Safety Code, Vehicle Code, and designated parts of the Federal Clean Air Act.

As mentioned above, the seven-member Board is made up of two supervisors from each of the three counties and one council member from the Town of Mammoth Lakes. The APCO is hired by the Board. The Board approves the creation of staff positions, and the APCO hires staff. The Hearing Board is appointed by the Board, and ideally consists of a doctor, a lawyer, an engineer and two members of the general public.


The District has two separate budgets: the “District budget” which covers the control of most traditional sources of air pollution (such as industrial, agricultural and woodsmoke sources) and the “SB 270 budget” which covers those activities connected with pollution caused by the water-gathering activities of the Los Angeles Department of Water and Power (DWP).

Funding for the District budget comes from the state, the federal government, fees that industry pays for permits to operate equipment that causes air pollution, fines on industries that violate our rules, and county and town contributions at $0.55 per capita (returned to the counties and the town since the 1992-93 fiscal year because of their financial difficulties). The 2004-2005 District budget is $645,000.

Funding for the SB 270 budget comes directly from the DWP. We have a special section in the California Health and Safety Code (§ 42316) that allows us to require the DWP to mitigate the air pollution they cause, and to pay the District’s costs to monitor the air pollution they cause, determine what needs to be done to solve the problems and oversee the implementation of the solutions. The 2004-2005 SB 270 budget is $4,631,000.


The District has 23 merit-system employees and 3 contract employees. Approximately 22 employee equivalents work under the SB 270 budget and four employee equivalents work under the District budget. An organizational chart with the employee positions and names is attached.


The District regulates seven pollutants called “criteria pollutants”: Ozone (03), Carbon Monoxide (CO), Lead, two types of Particulate Matter (PM-10 and PM-2.5), Sulfur Oxides (SOx) and Nitrogen Oxides (NOx). We also regulate Hydrogen Sulfide (H2S) under a state standard. California has a toxics program that adopts regulations for particular sources of toxics, such as benzene from retail service stations, which the district is then required by state law to enforce. Title III of the Clean Air Act Amendments of 1990 also regulates toxics.

The primary air pollutant present in the District is particulate matter (PM). That vast majority of our efforts go toward controlling this pollutant. As mentioned above, two types of PM are regulated: PM-10 and PM-2.5. The difference is the size of the particles—PM-10 is particulate matter with an average maximum size of 10 microns and PM-2.5 is PM that is 2.5 microns or smaller. These are very small particles—a particle of PM-10 is about one-seventh the diameter of a human hair. The District monitors PM-10 levels at 9 locations in Inyo County and 3 locations in Mono County. Much of the PM-10 we monitor comes from wood burning or dust from Owens and Mono Lakes. We monitor PM-2.5 in Keeler and Mammoth Lakes. We have four stations that monitor hydrogen sulfide from the Coso geothermal development. All of the monitoring sites include meteorological stations.

Major Sources of Air Pollution

Owens Lake is the largest single source of PM-10 in the United States. The Federal Clean Air Act required that the District produce a State Implementation Plan (SIP) in 1997 that detailed how we would control this problem. The District signed an agreement with the City of Los Angeles in 1998 that set a schedule for implementing controls. These controls were approved by USEPA. So far, dust controls have been installed by the DWP on about 19.25 square miles (over 12,000 acres) of the lakebed. The PM-10 levels must be reduced to the federal standard by 2006 or the District will be subject to federal sanctions, which could include withholding of federal highway funds. The District’s 2003 SIP revision (attached) requires a total of 30 square miles to be controlled by the end of 2006, and additional areas if necessary to meet the standard as they are verified. District staff devotes considerable resources to monitoring the dust from Owens Lake and enforcing the proper installation and operation of dust control measures.

Mono Lake also violates the federal PM-10 standard. The State Water Resources Control Board considered this in setting the required Mono Lake level in 1994. The District’s Mono Basin SIP was approved by the State in 1995 and sent to the EPA. The lake has risen about 10 feet since the mid-90s and PM-10 levels at some sites have decreased. The lake level needs to raise approximately nine more feet in order to sufficiently control PM-10 emissions.

Mammoth Lakes has high levels of PM-10 in the winter due to a combination of wood smoke and cinders put on icy roads for traction during the winter. In cooperation with the District, the Town developed an ordinance in 1990 to control both sources. The Mammoth Lakes SIP was submitted to the federal government and it has been approved. Since implementation of the ordinance, PM-10 levels have dropped significantly.

The Coso geothermal development east of Coso Junction on the China Lakes Naval Weapons Center property has the potential to violate the state standard for hydrogen sulfide, but has not yet done so because the standard does not apply on the Naval Weapons Center property. We have worked with the geothermal developers to minimize the emissions from each power plant and well in order to allow full development without a violation of the standard off the base.

Major Past Policy Decisions

In 1985, the Board decided to develop the mitigation measures for Owens Lake rather than ordering the DWP to develop them. The Board felt the District had more incentive to find a workable solution than the DWP.

In 1989, the Board decided to give the Town of Mammoth Lakes the opportunity to select its own controls for PM-10 from a list developed by the District as long as those controls appeared likely to eliminate the federal standard violations. This reinforced the good relationship the District had with the Town of Mammoth Lakes, and led to a plan acceptable to all parties.

In 1991, the Board decided to make AB 2588 (a state law requiring a sources of toxics to do plans, inventories, source tests and reports) a low priority for staff enforcement.

The Board’s preferred mitigation measure for Mono Lake has been to keep the lake level high enough to prevent federal air quality standard violations. Staff presented testimony at the Water Board Hearings that a lake level of 6392 feet or higher was necessary to meet the Federal Standards. The Water Board adopted that level in its 1994 decision.

In 1996, the Board chose shallow flooding, gravel, and managed vegetation as the control measures for Owens Lake. In 1998, the Board adopted the Owens Valley State Implementation Plan (SIP) that began the process of controlling the PM-10 from the Owens Lake. In 2003, the Board adopted the final SIP to control 99% of the dust from 30 square miles of the lake bed, and to have an automatic provision for controlling other areas if they become emissive. The 2003 SIP also allows DWP, after the federal standards are attained, to fine-tune the controls, as long as the standards are maintained.

Current and Upcoming Issues

Owens Lake – As mentioned above, by the end of 2006 the City of Los Angeles must complete the construction of almost 30 square miles (19,000 acres) of dust controls on the emissive portions of the Owens Lake bed. This project is estimated to cost $415 million. District staff is very involved in the oversight of the City’s work, ensuring compliance with environmental impact mitigation measures and continuing to monitor the emissions from the lake bed. The adopted State Implementation Plan requires emissions monitoring to continue after 2006 in order to identify if any additional areas on the lake bed need controls in order to comply with the federal PM-10 standard.

Mono Lake – The District continues to monitor the progress at Mono Lake. Air monitors and equipment on the emissive areas will quantify the levels of air pollution coming from the lake. The District will determine if the air quality improvements set forth in the State Implementation Plan remain on schedule.

Mammoth Lakes – Since 1990, the Town of Mammoth Lakes has done an exemplary job of implementing measures to reduce air pollution in the town caused primarily by woodsmoke and the dust from materials used for ice control on roadways. However, the town is growing rapidly and plans to continue to do so. The District needs to work with the Town to ensure that the air quality progress we have made over the last 15 years is not jeopardized as the Town continues to develop.

Agricultural Air Pollution (SB 700) – Agricultural operations in California cause significant levels of air pollution in some areas of the state. Recent laws adopted by the State of California (SB 700) now require agricultural operations to comply with all air pollution regulations. Previously, agriculture was exempt from most air pollution laws. The District is required to adopt new rules and revise old ones by July 1, 2005 in order to comply with the new state laws. The first public meeting regarding agricultural regulations was held last September. The District Board asked staff to form an “Agricultural Activities Rule Development Workgroup” to work with local agricultural operators and interested members of the public. Staff will be conducting meetings this winter and spring with the aim of adopting the new rules before July.

State Particulate Matter Standards (SB 656) – The efforts to meet particulate matter (PM-10) standards in the District (Owens Lake, Mono Lake and Mammoth Lakes) have focused on the federal PM-10 standards (the 24-hour standard is 150 µg/m3 and the annual standard is 50 µg/m3). In addition, the State of California has adopted state PM-10 standards that are more stringent than the federal standards (the 24-hour standard is 50 µg/m3 and the annual standard is 20 µg/m3). A recently adopted state law (SB 656) requires the District to begin the planning necessary to meet the state standards for both PM-10 and the smaller PM-2.5 particles. The District is required to adopt an implementation schedule by July 31, 2005 and then begin working to cost-effectively implement measures to make progress toward meeting the state PM standards. Staff is compiling data and information that we will present to the Board this spring in order to meet the requirements of SB 656.

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