SIP Approval: Iowa (updates to incorporations by reference to methods for performance testing, updates to definitions, and adoption of most recent ozone NAAQS). 

SIP Proposal: Iowa (revisions to definitions, references to federal rules, and methods and procedures for performance test/stack test and continuous monitoring system). 

EPA established new emissions standards for criteria pollutants and greenhouse gases (GHGs) for light- and medium-duty vehicles that will phase in over model years 2027 through 2032; finalized revisions to the GHG program; established new standards to control refueling emissions from incomplete medium-duty vehicles, as well as battery durability and warranty requirements for light- and medium-duty electric and plug-in hybrid electric vehicles; and finalized minor amendments to update program requirements related to aftermarket fuel conversions, importing vehicles and engines, evaporative emission test procedures, and test fuel specifications for measuring fuel economy. 

EPA finalized a rule to remove the Title V permitting requirements for air curtain incinerators that only burn wood waste, clean lumber, yard waste, or a mixture of those, and are not located at title V major sources or subject to Title V for other reasons. 

United States v. Colonial Oil Industries, Inc., No. 4:24-cv-00069-RSB-CLR (S.D. Ga. Apr. 10, 2024). Under a proposed consent decree, a settling CAA defendant that allegedly failed to meet renewable fuel volume obligations for fuel it supplied to certain marine vessels and produced and sold gasoline that exceeded the applicable volatility standard must purchase and retire over 9 million renewable identification number credits, estimated to cost approximately $12.2 million, and pay a civil penalty of approximately $2.8 million.  

EPA finalized changes to its test procedures required to be used by industries and municipalities when analyzing the chemical, physical, and biological properties of wastewater and other samples for reporting under the NPDES permit program. 

SIP Proposal: California (revisions to meet requirements for the 1997 eight-hour ozone NAAQS in the Riverside County nonattainment area). 

SIP Proposal: Arizona (revisions concerning emissions of volatile organic compounds, nitrogen oxides, particulate matter, and sulfur oxides for the Maricopa County Air Quality Department).  

United States v. Villegas, No. 1:24-cv-962 (D. Colo. Apr. 10, 2024). Under a proposed consent decree, settling CWA defendants that discharged pollutants without a permit into waters of the United States must restore impacted areas. 

United States v. Lexington-Fayette Urban County Government, No. 5:06-cv-386-KSF (E.D. Ky. Apr. 10, 2024). A proposed material modification to a consent decree concerning alleged violations of the CWA stemming from the settling defendant's operation of its sanitary sewer system and wastewater treatment plant extends the final compliance deadline for remedial projects by four years to December 31, 2030, and makes changes to reporting frequency and methods.