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In the early 1990's, the Federal Clean Water Act was amended to require select urban areas to have a municipal stormwater (or MS4) permit. In Oregon, this program was delegated to the Oregon Department of Environmental Quality (DEQ). Clackamas County was one of the jurisdictions required to obtain an NPDES permit, and the City of Lake Oswego is one of the 13 co-permittees on the Clackamas County permit. The City of Lake Oswego received their NPDES stormwater permit from DEQ in 1995. The NPDES Permit has subsequently been renewed in 2004, 2012, 2017, and is due for renewal again on March 1, 2022.
The permit requires the City to:
1. Manage stormwater at City facilities and on the City right or way
2. Require stormwater management on private parcels as they develop or redevelop
3. See that stormwater facilities are properly operated and maintained
4. Provide additional oversight for high pollutant-load generating areas (industrial & commercial)
5. Control erosion from construction
6. Control non-stormwater discharges to the storm drainage system
7. Provide public and staff education and outreach around stormwater best practices
8. Provide opportunity for public involvement and participation, particularly at the time of permit renewal
9. Undertake targeted evaluations of specific issues as required by DEQ
10. Monitor the stormwater system; and
11. Report annually on City activities related to the permit. (Recent annual reports are available online.)
Stormwater Management Manual
The 2020 Stormwater Management Manual (SWMM) effective October 1, provides guidance on the siting, design, and maintenance of structures used to manage stormwater from impervious surfaces in the City. The manual applies to stormwater management design for public and private development and redevelopment within the City of Lake Oswego. The Engineering Department revises the SWMM to meet current regulatory requirements and technical standards.
As part of the final erosion and sediment control inspection, documentation is required from private developers attesting to the stormwater facility’s adherence to the SWMM and an operations and maintenance plan recorded at the County. Other documentation required of private developers when the facility is an underground injection control is a copy of the DEQ approval of the facility.
- October 2020 Lake Oswego Stormwater Management Manual
- October 2020 Lake Oswego Stormwater Management Manual Appendices
Buy, Use, and Dispose of Household Products Wisely to Help Protect Our Water
The products you use for cleaning contain ingredients that may harm you, your family and the environment. Using household products incorrectly can allow dangerous chemicals to enter Oregon’s streams and rivers.
The City of Lake Oswego's obligations toward our stormwater permit ("municipal separate storm sewer" or MS4) and related water quality ("total maximum daily load" or TMDL) are outlined in a number of plans and progress reports, provided as Supporting Documents. These Supporting Documents are prepared by the City in response to the MS4 permit and TMDL analyses.
Stormwater runoff occurs on dispersed land surfaces including pavements, yards, driveways, and roofs. Runoff picks up pollutants that are then transported down curb and gutters, pipes, and ditches to our streams and Oswego Lake. Improving water quality requires that we are careful about what we allow onto the land surface, either intentionally or unintentionally.
Lake Oswego is committed to protecting the environment of the city and the surrounding area through its Stormwater Management Utility. In an effort to further protect our water sources, Erosion Control Permits are required for construction projects under any of the following circumstances:
In an effort to proactively keep illicit discharges from happening, the City implements a program of inspections, dry weather field screening, and monitoring to detect any potential illicit discharges to the Stormwater System.
The City of Lake Oswego has developed an inventory of all industrial and commercial sources of stormwater discharge in the City.
The City of Lake Oswego conducts a variety of activities focused on the prevention of typical stormwater pollutants (sediment, hydrocarbons, trash and debris, nutrients, metals) from entering the MS4 system. Such activities include the maintenance and repair of City streets; the maintenance of public parks and recreational areas with the intent of minimizing fertilizer and pesticide use; the maintenance of municipal facilities; control of potential cross-connections from the sanitary sewer system; and master planning for stormwater quality improvement.
The City of Lake Oswego Planning, Public Works, and Building divisions share review responsibilities for development applications.
The City provides opportunities for public participation in the development, implementation, and modification of the policies, practices, procedures, and codes that comprise the City’s Stormwater Management Plan (SWMP) and pollutant load reduction benchmark development.
The City of Lake Oswego conducts a variety of activities focused on the prevention of typical stormwater pollutants (sediment, hydrocarbons, trash, debris, nutrients and metals) from entering the M