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City of Lake Oswego

Stormwater Program


In the early 1990's, the Federal Clean Water Act required urban areas with populations greater than 100,000 to apply for and obtain a National Pollutant Discharge Elimination System (NPDES) permit for their stormwater discharges.

In Oregon, this program was delegated to the Oregon Department of Environmental Quality (DEQ).

As a result, DEQ directed six Oregon jurisdictions and associated co-permittees to apply for and obtain a municipal NPDES stormwater permit. 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 and in 2012.

Stormwater Management Manual

The City of Lake Oswego is pleased to announce the release of a revised December 2015 draft of our new Stormwater Manual. FAQs on the Code and Manual are here. This draft includes modifications since the July 2015 draft proposed during the fall land use review public process.

This Manual, and related amendments to the City’s drainage and surface water utility codes, is a requirement of our current NPDES stormwater permit. The Manual emphasizes the use of infiltration-based approaches to stormwater management where possible, along with other low-impact development (LID) techniques to minimize runoff from roofs, streets, driveways, and other impervious surfaces. The manual will apply to the design of newly developing and re-developing sites, and has requirements based on different thresholds of impervious surface area.

  • View the December 2015 draft of the Stormwater Management Manual here.
  • View Appendices (July 2015) here.
  • View Stormwater Manual Design Workshop presentation here.
  • View Stormwater Manual Open House presentation here.

Comments on the Public Review Draft Lake Oswego Stormwater Management Manual can be sent to the City here.

Some of the code amendments require concurrence of the Planning Commission, and all code changes require approval by the City Council. The current schedule for these actions is:

  • January 11, 2016: Planning Commission findings
  • January 19, 2016: Study Session
  • February 2, 2016: City Council hearing
  • February 16, 2016: City Council adoption
  • March 18, 2016: City Council decision becomes effective

Links to the proposed code amendments and supporting documents related to the adoption process can be found after here.

For those of you wanting more information on Low Impact Development Techniques, check out this video: Reduce Runoff: Slow It Down, Spread it Out, Soak It In [8:43 minutes]