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City of Lake Oswego

Stormwater Program


In the early 1990's, the Federal Clean Water Act required municipalities with populations greater than 100,000 (including areas municipal separate storm sewers located within the boundaries of a region defined by a storm water management regional authority based on a jurisdictional, watershed, or other appropriate basis that includes one or more of the systems) 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. 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 the public review draft of our new Stormwater Manual. FAQs on the Code and Manual are here.

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 a draft of the Stormwater Management Manual here. Modifications from July through November are here.
  • View Appendices 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. Comments on the manual received by October 31, 2015, will be addressed in the Staff Report for the upcoming Planning Commission hearing on accompanying code amendments.

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:

  • October 26, 2015: Joint Planning Commission / Development Review Commission work session
  • November 23, 2015: Planning Commission hearing
  • December 14, 2015 Planning Commission findings
  • January 5, 2016: City Council hearing
  • January 19, 2016: City Council adoption
  • February 18, 2016: Code becomes effective

Links to the proposed code amendments and supporting documents can be found after October 16, 2015 here as part of the agenda for the October 26th Planning Commission meeting.