The battle over regional haze in Texas continued this week, as EPA published a final rule for the state to address visibility degradation in its national parks. The rule itself appears relatively plain on its face—it simply approves for Texas a regional haze policy that is similar to what EPA has approved for many other states. That is, it deems compliance with an emission trading program to be sufficient to satisfy the regional haze requirement for Best Available Retrofit Technology (BART). However, the Texas rule is the most recent and obvious indication that the Trump EPA is taking a very different tack on regional haze than the Obama EPA.

The general policy underlying the new Texas regional haze rule, of using an emission trading program to satisfy BART, is nothing new. In fact, it was first developed under the Bush Administration, when EPA determined that the emission trading program established under the Clean Air Interstate Rule (CAIR) was sufficient to satisfy BART. Support for that policy continued under the Obama Administration, even as CAIR was replaced by the Cross-State Air Pollution Rule (CSAPR). The question of whether CSAPR is equal to or more stringent than BART remains under litigation (oral arguments will be held in November). However, the use of a more stringent emissions trading program—or really any more stringent emission reduction program—as an “alternative to BART” is well-grounded in the Clean Air Act visibility provisions.

But for Texas, use of an emission trading program to satisfy BART represents a significant change in policy, in light of the two proposed rules that the Obama EPA issued for the state last year. To recap, the Obama EPA’s first answer for regional haze in Texas skipped BART entirely, but still ordered the state to install $2 billion in scrubbers on specific power plants, under a different requirement known as “reasonable progress.” Once finalized, Texas challenged that rule in the Fifth Circuit and won a stay. Unlike the many other courts that have previously deferred to EPA’s aggressive interpretation of its regional haze authority, the Fifth Circuit characterized EPA’s regional haze authority as “ministerial,” and also noted how minimal the change in visibility would be compared to the cost of the controls required. Recognizing this defeat in court, the Obama EPA withdrew its first rule and issued a second proposal for Texas in its waning days. This second proposal returned to its tried-and-true BART authority, but the ultimate result was remarkably similar to its “reasonable progress” rule—billions of dollars in scrubber controls on specific power plants.

The Trump EPA’s action this week purports to finalize that second Obama EPA proposal, but differs from it almost entirely. Rather than imposing source-specific BART as proposed, the newly finalized rule adopts an “alternative to BART” touted as “better-than-BART,” namely an intrastate emission trading program modeled after CSAPR. Whether such a radical shift from Obama EPA proposal to Trump EPA final rule will pass legal muster remains to be seen, but the shift confirms that the new Trump EPA has very different view of the regional haze program than the Obama EPA.