What is an MS4?
To address non-point source pollution, the U.S. Environmental Protection Agency (EPA) developed the Municipal Separate Storm Sewer Systems (MS4) permit through its national pollutant discharge elimination system (NPDES) under the commonly referred to Clean Water Act. The Oregon Department of Environmental Quality (DEQ) is the state agency authorized to issue MS4 Phase I and Phase II General Permits. Based on its population, the City of Troutdale has been issued a NPDES MS4 Phase II General Permit.
Why do we need an MS4 permit?
As precipitation flows over rooftops, streets and yards, it has the potential to pick up and carry pollutants like bacteria, fertilizers, metals, oil, sediment, trash, and other examples into the storm sewer system and dump it into our surface water and groundwater. These non-point source pollutants are commonly associated with urban development. An MS4 permit outlines the actions to help reduce pollutants from entering the water we all rely on for drinking and recreating in.
What does the City of Troutdale need to do?
Under this permit, the City of Troutdale is responsible for creating and implementing a stormwater management program in the following six (6) areas called control measures:
- Public Education and Outreach
- Public Involvement and Participation
- Illicit Discharge Detection and Elimination
- Construction Site Runoff Control
- Post-Construction Site Runoff for New Development and Redevelopment
- Pollution Prevention and Good Housekeeping for Municipal Operations
What does the MS4 permit mean in terms of regulations?
The City of Troutdale addresses stormwater regulations in the following areas:
- Storm Sewer System under Chapter 12.06 of the Troutdale Municipal Code
- Post-Construction Site Runoff Control under the 2016 City of Portland Stormwater Management Manual and Source Control Manual, and Construction Standards for Public Works Facilities: Interim Change No. 35
- Erosion Control under Chapter 12.09 of the Troutdale Municipal Code and Construction Standards for Public Works Facilities: Interim Change No. 34
- Erosion Control Permits for one acre or more under the NPDES 1200-C; and 1,000 square fee or more, but less than once acre under the 1200-CN
