Background Information

NPDES Phase II Storm Water Program

In 1972, Congress took aim at industrial wastewater and municipal sewage discharges by passing the Federal Water Pollution Control Act Amendments, commonly known as the Clean Water Act. The purpose of the act was to "restore and maintain the chemical, physical, and biological integrity of the Nation's waters." The Clean Water Act allowed the states to administer the National Pollutant Discharge Elimination System (NPDES) program. Once the U.S. EPA approved their request, state NPDES authorities administered the program consistent with minimum federal requirements for monitoring, reporting, enforcement, and other practices.

In 1987 Congress enacted the Water Quality Act (WQA), which amended the 1972 Clean Water Act and required the U.S. EPA to apply NPDES permit program requirements to farms, factories, and city streets.

Then, beginning in 1990, the EPA required large municipalities, certain industrial facilities, and construction sites disturbing at least 5 acres of land to obtain NPDES permits for their stormwater discharges. Dubbed "Phase I," the program required municipal separate storm sewer systems (MS4s) located in counties or metropolitan areas with populations larger than 100,000 to obtain NPDES permit coverage.

In 1998, the EPA proposed regulations to expand the NPDES Phase I stormwater program to include small municipalities and counties, as well as construction sites disturbing at least 1 acre of land. On December 8, 1999, the EPA issued regulations that expanded the existing NPDES Storm Water Program to regulate most MS4 entities (cities, towns, universities, colleges, correctional facilities, hospitals, conservancy districts, homeowner's associations and military bases) located within mapped urbanized areas, as delineated by the U.S. Census Bureau, or, for those MS4 areas outside of urbanized areas, serving an urban population greater than 7,000 people. In addition to these generalized criteria, designation of MS4 entities is potentially determined by other factors, including population growth and documentation which indicates water quality impairment. These regulations are referred to as the NPDES Phase II Storm Water Program. The urbanized area of Allen County, the Town of Huntertown, and the Town of Leo-Cedarville met these criteria and were consequently designated as MS4 entities.

In the State of Indiana, the Indiana Department of Environmental Management (IDEM) is responsible for the development and oversight of the NPDES Phase II Program. IDEM initiated adoption of the Phase II Rules that were codified as 327 IAC 15-13 (Rule 13) that became effective on August 6, 2003. IDEM also revised Rule 5 (327 IAC 15-5), which specifies pollution prevention requirements for storm water discharges from construction activities. Rule 13 required designated MS4 entities to apply for permit coverage by submitting a Notice of Intent (NOI) and developing Storm Water Quality Management Plans (SWQMPs) through a phased submittal process. On December 18, 2021, IDEM issued a Municipal Separate Storm Sewer General Permit (MS4GP) and a Construction Stormwater General Permit (CSGP). The MS4GP replaced 327 IAC 15-13 (Rule 13) that had previously established the permitting requirements for all designated MS4s in Indiana. The CSGP replaces the requirements of IDEM’s Rule 5. The CSGP is a performance-based regulation designed to reduce pollutants that are associated with construction and/or land-disturbing activities and regulates discharges of stormwater from construction activities into surface waters of the State of Indiana. These General Permits provide new water quality regulatory requirements and require all MS4s to update their storm water quality programs.

Allen County and the Towns of Huntertown and Leo-Cedarville are completing the updates to their storm water quality program that are required in the new General Permits and are moving forward with an updated Program Implementation Plan.