Air Quality Regulations Governing Farm-Based Diesel Engines Upheld

June 1, 2011 | Erin Herbold-Swalwell


The California Air Resources Board (CARB) is responsible for regulating air pollution in the State of California by developing measures to control the emission of airborne toxins. In 1998 CARB determined that particulate matter emissions from diesel-fueled engines were a toxic air contaminant.  In 2004, CARB adopted an airborne toxic control measure designed to address particulate emissions from diesel vehicles. Under state law, local pollution control districts are responsible for controlling air pollution from all non-motor vehicle emissions.  So, when CARB adopted its measure in 2004, local districts had to adopt rules to carry-out the measure.  The defendant, a local pollution control district covering Monterey, Santa Cruz and San Benito Counties, adopted rules in 2007 requiring owners and operators in the district to register and pay fees for diesel engines of 50 brake horsepower (bhp) or larger that are used for agricultural operations.  Another rule established an emission standard for covered diesel engines.

The plaintiff, a California family farming corporation, uses diesel engines to provide power to farm irrigation pumps.  The  plaintiff sued, claiming that the rules adopted by the district were preempted by the Federal Clean Air Act (CAA), violated state law and violated the plaintiff’s constitutional due process rights.  But, the trial court determined that the rules were not preempted by the CAA because they did not relate to the control of emissions – they only sought to gather information and collect fees. The trial court also held that the rules did not violate California law and did not violate the plaintiff’s due process rights because the district had a rational basis for adopting the rules – there was a legitimate state interest in controlling air pollution in the district. 

Note:  The court did not explain how its finding that the rules did not relate  to the control of emissions squared  with its finding that the rules didn’t violate the plaintiff’s due process rights because the district had a legitimate interest in controlling air pollution in the district.

On appeal, the court affirmed.  The court reasoned that the CAA governs emissions from both “stationary and mobile sources” and is designed to work with the states to control emissions.  Thus, the direct regulation of emissions from stationary sources is generally left to the states while the Federal government normally attempts to regulate “mobile sources” such as motor vehicles or nonroad engines. The rationale behind the split of authority is that mobile sources cross state lines.

The CAA expressly preempts states from setting emissions standards for mobile sources.  So, the legal question was whether federal preemption under the CAA should have invalidated the district’s rules as they applied to the plaintiff.  The court held that express preemption under the CAA did not apply.  According to the court, a state may not regulate the emissions of new off-road engines (farm engines) under 175 bhp.  But, off-road engines may be regulated if the district first obtains permission from the EPA.   The district did not obtain the necessary permission, but the court found that the first two rules promulgated by the district did not really regulate emissions after all.  They were simply registration and fee requirements that did not impose any regulations on the manufacturers of diesel engines.  While the third rule “unquestionably” set emission standards, the court determined that it was carefully tailored and applied only to “stationary” engines, such as the diesel engines used in irrigation.  The regulation of emissions from “stationary” objects is within a state’s domain to regulate. The court found that the engines at issue in this case, “remain or will remain at a location for more than 12 consecutive months or a shorter period of time…”.  In addition, the court stated that, “any engine that replaces an engine at a location and that is intended to perform the same or similar function as the engine replaced will be included in calculating the consecutive time period.”  

The plaintiff also claimed that California law preempted the rules under the state’s “Portable Equipment Registration Program.”  But, the court found that the PERP program was voluntary and if the owner does not register under the program they are subject to the district’s permitting requirements. The appellate court also denied the farm’s due process claim.Jensen Family Farms, Inc. v. Monterey Bay Unified Air Pollution Control District, et al., No. 09-16790, 2011 U.S. App. LEXIS 10680 (9th Cir. May 27, 2011).