dissenting:
I respectfully disagree with my colleagues that TCM 2 does not impose an enforceable obligation on MTC. Regardless of whether the “plain language” of TCM 2 suggests that the 15% ridership increase is best construed as an “obligation” or a “commitment” or a “target” or a “requirement,” it is undeniable that the Clean Air Act requires that state implementation plans be submitted to EPA in an “enforceable form.” See Clean Air Act (“CAA”), 42 U.S.C. § 7502(c); Trustees for Alaska v. Fink, 17 F.3d 1209, 1212 (9th Cir.1994). When the EPA approved TCM 2 as a component of California’s SIP in 1984, the measure became a federally enforceable regulation, and it remains so as long as it is included in the SIP. If the 15% ridership increase provision in TCM 2 were not binding, then the measure would not truly have been in enforceable form, and it would thus have been in violation of the Clean Air Act.
The majority suggests that the 15% ridership increase figure is a mere aspiration, or that it is similar to a “statement of opinion,” or a “prediction as to future events.” The majority also acknowledges, however, that TCMs must be submitted in enforceable form, and that “aims and goals of the SIP are not enforceable apart from specific TCM strategies.” Id. The majority thus holds that what meets the requirement of “enforceable form” in TCM 2 are the steps contained in TCM 2’s “Implementation Schedule” and the “productivity improvements” mentioned in TCM 2’s “Control Measure” section.
If only the Implementation Schedule and the Control Measure section of TCM 2 were enforceable, however, then all that MTC could be required to do under TCM 2 is “consult” with operators, “seek to ensure” implementation of transit operators’ 5-year plans through the Transportation Improvements Plan, and “monitor” ridership gains through RFP reports. See TCM 2 (emphasis added). It is difficult to imagine that a transportation commission could ever be said to have failed to achieve such vague “requirements,” such that that commission could actually be compelled to meet those “standards” by way of an enforcement action by the EPA. This brand of “enforceability” is too attenuated and amorphous to serve the ultimate attainment of federal air quality standards, as envisioned by the statute. See 42 U.S.C. § 7502(c).
The majority also fails to explain how the “plain language” of the statement *705“[s]ince federal funds for transit purposes are being cut back, many of the improvements identified in the 5-year plans deal with increased productivity” is clearly different from a “statement of opinion” or a simple description, or why a description of regional plans as “dealing with increased productivity” should be interpreted as a requirement that certain of these “many” improvements be enforced.
The EPA is the agency responsible for interpreting SIPs; the Agency clearly found that TCM 2, as well as the other TCMs implemented under the 1982 SIP, contained quantifiable emissions reductions, saying the TCMs “clearly have emissions reduction in the SIP,” and that any new measures proposed by MTC would need “to provide the equivalent or greater emissions reductions.” The regional EPA air division director stated further in an opinion letter that “[w]e believe that TCM 2 will be fully implemented only when transit ridership increases by 15% from 1982-83 levels.” This opinion, taken in the context of the requirement that SIPs be submitted in enforceable form, is persuasive. See Christensen v. Harris County, 529 U.S. 576, 587-88, 120 S.Ct. 1655, 146 L.Ed.2d 621 (2000).
The fact that MTC submitted what it now considers an unrealistic TCM to the EPA, for whatever reason, should not affect the regular, predictable application of the Clean Air Act’s enforcement mechanisms. As the district court said, “[without this judicial check, state and local governments could use a conditional commitment as a gimmick to delay indefinitely hard political choices.... ” Bayview, et al. v. MTC, 177 F.Supp.2d 1011, 1212 (N.D.Cal.2001). Without methodical enforcement, local and regional agencies could define their commitments as vaguely as possible in order to avoid constraint and reform, and then later redefine strictures away if faced with unpopular tradeoffs. If MTC finds that it cannot meet the 15% requirement, it may plead its case to the EPA, and it may take advantage of the CAA’s “exclusive modification mechanisms.” See 42 U.S.C. §§ 7410(n)(1), 7410(l); General Motors Corp. v. United States, 496 U.S. 530, 533, 110 S.Ct. 2528, 110 L.Ed.2d 480 (1990). MTC can propose a new measure to the EPA that, ensures at least the same level of emission reductions of ozone precursors in the SIP as TCM 2. See 42 U.S.C. § 7515. MTC has had this option available to it for years, but it has submitted no alternate proposals. Hence, TCM 2 remains in the SIP, and is enforceable until substituted.
In sum, the regular statutory procedures for altering SIPs are not only the most effective manner in which to proceed, but the one mandated by Congress. In my view, the district court was entirely correct in concluding that MTC cannot unilaterally alter its obligations under TCM 2 outside of the mechanism provided by statute.
Thus, I would affirm the district court’s well-reásoned order in its entirety.