Whether the Clean Water Act and NPDES rules require a demonstration of causation beyond a 'mere possibility' to impose more restrictive effluent limitations when applying a state's narrative water quality criteria

QUESTIONS PRESENTED The EPA issued an NPDES permit to Taunton, Massachusetts imposing state of the art total nitrogen (“TN”) reduction requirements. EPA’s action was premised on the claim that TN was causing a narrative criteria violation (excessive algal growth) leading to low dissolved oxygen (DO) in the Upper Taunton Estuary. Taunton challenged this action on regulatory and scientific grounds because, inter alia, the available data showed no meaningful relationship between DO, algal growth and TN in the Upper Taunton Estuary. The First Circuit, citing Chevron and Auer, accepted, without detailed review, EPA’s statutory and regulatory interpretations that (a) EPA did not have to demonstrate “causation” to impose stringent TN limitations when implementing a state narrative standard, and (b) EPA’s findings are upheld if there is a “mere possibility” they are correct. The Court also concluded it was not empowered to “second guess” any of EPA’s technical conclusions Taunton challenged. The Questions Presented are: (1) Do the Clean Water Act and NPDES rules require a “causation” demonstration beyond a “mere possibility” to impose more restrictive effluent limitations when applying Massachusetts’s narrative criteria? (2) Should this Court narrow or overturn its rulings in Chevron and Auer, to ensure meaningful, independent judicial review because those decisions are being used to create extreme deference in reviewing agency action, raising substantive due process concerns?