 DEP is also responsible for managing the city's combined sewer system, which carries both storm water runoff and sanitary waste, and fourteen wastewater treatment plants located throughout the city.DEP carries out federal Clean Water Act rules and regulations, handles hazardous materials emergencies and toxic site remediation, oversees asbestos monitoring and removal, enforces the city's air and noise codes, bills and collects on city water and sewer accounts, and manages citywide water conservation programs.Its regulations are compiled in title 15 of the "New York City Rules".