Stormwater discharge is regulated under the clean water framework, with obligations on both municipalities and construction sites.
Municipal separate storm sewer systems. Operators hold permits requiring a stormwater management programme with defined minimum measures: public education, public involvement, illicit discharge detection and elimination, construction site runoff control, post-construction runoff control, and pollution prevention for municipal operations.
Ordinance requirements. Permittees must adopt ordinances implementing construction and post-construction controls, with enforcement authority, and must actually enforce them — programme reporting is audited.
Construction site permits. Sites above an area threshold require coverage under a construction general permit, a stormwater pollution prevention plan, installation and maintenance of controls, inspections at defined frequencies, and records.
Post-construction. Permanent controls — detention, infiltration, green infrastructure — with a recorded maintenance agreement assigning long-term responsibility, which is the provision most often omitted.
Enforcement. Federal, state and citizen suits, with civil penalties per day per violation. Citizen suits are a significant enforcement channel and require sixty days’ notice.
Practical municipal exposure. Inadequate inspection records and unenforced ordinances are the recurring findings in programme audits.