Digging into the actual text of this one since nobody seems to be reporting on the decision with any sort of detail. But it's a really dense one: > In sum, we

Digging into the actual text of this one since nobody seems to be reporting on the decision with any sort of detail. But it's a really dense one: > In sum, we hold that §1311(b)(1)(C) does not authorize the EPA to include “end-result” provisions in NPDES permits. Determining what steps a permittee must take to ensure that water quality standards are met is the EPA’s responsibility, and Congress has given it the tools needed to make that determination. If the EPA does what the CWA demands, water quality will not suffer. TL;DR (As near as I can understand): The EPA changed the permitting requirements for San Francisco's wastewater treatment plants and made it so they were on the hook for any pollution in the surrounding water. SF originally argued that the EPA was unlawfully enforcing this requirement (that the law does not bind them to spillovers that happen when their plants are overloaded). The court rejected this argument but substituted one of their own: The EPA tells the plants how to operate under the NPDES permits - it can't then also make the plants on the hook for the outcomes. The dissent also has lots of good points: If the water goals were unachievable, the city could have sued on those grounds. It's also probably a better idea to let mandate the outcomes and let plants come up with the best way to achieve them then for the EPA to micromanage every plant. And the EPA has to micromanage every single plant to which they issue permits, they may not be able to issue as many permits! But it's also worth noting that there was not a single amicus brief submitted supporting the EPA on this one.