The court affirmed that the state Department of Environmental Conservation (DEC) is responsible, under the federal Clean Water Act and state law, for ensuring that stormwater pollution is reduced “to the maximum extent practicable” — and reduced to low enough levels that it no longer puts hundreds of water bodies out of compliance with state water quality standards. Specifically, the court ordered DEC to re-write the MS4 General Permit to correct three fatal flaws: 

• Lack of DEC oversight: The permit abdicated DEC’s responsibility to review municipalities’ stormwater pollution control measures, to ensure they are sufficient to meet Clean Water Act standards. Instead, the permit allowed municipalities to self-certify their own plans, creating unchecked opportunities for “misunderstanding, misrepresenting, or misapplying” the applicable requirements. 
• Missing compliance schedules: For cities and towns that send their runoff into water bodies where DEC has established pollution reduction budgets (i.e., TMDLs), the permit failed to establish “compliance schedules” to reduce runoff. These compliance schedules must include both interim and final deadlines, to ensure steady progress towards meeting the state’s long-term pollution reduction targets. 
• Excluding public participation: The permit denied the general public the right to participate in a DEC hearing, in connection with the agency’s review of each municipality’s proposed stormwater pollution control measures, at which concerned citizens may object to proposals that fail to meet state and federal standards. Citizen groups often use such Clean Water Act permit hearings to introduce expert testimony — or even their own data and observations drawn from community-based sampling and knowledge of local conditions — in support of stronger water quality protections.