Permits, Plans, and Reports

  • The City is committed to maintaining water quality through multiple programs required by Oregon Department of Environmental Quality (DEQ). Each year, the City prepares and submits the MS4/TMDL Report and the UIC Report to DEQ, describing efforts to manage water quality in the City for the prior fiscal year.

To comment on any of the following permits and plans, complete this comment form

The City manages the following permits and plans:

NPDES Phase 1 MS4 Permit

The National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer Systems (MS4) Phase 1 Permit includes requirements for construction sites, development, maintenance of the system, public education, spills, and other pollution prevention measures.

  • 2021 Permit (MS4)
  • Plans
    • Stormwater Management Plan - this is the City's comprehensive plan to keep the rivers and streams in Lake Oswego clean and healthy. 
    • Monitoring Plan – this describes the City's monitoring objectives, strategy, and procedures for collecting and analyzing stormwater and surface water samples.  The City monitors water quality at six sites located at Ball Creek, Carter Creek, Springbrook Creek, Nettle Creek, Lost Dog Creek, and at Lamont Springs.  It also characterizes stormwater at two sites during two rain events per year.
  • Recent Report


The Total Maximum Daily Load (TMDL) program includes many of the same requirements as the MS4 program, but also incorporates measures that stabilize stream temperatures. The affected watersheds within the City’s jurisdiction include the Willamette and Tualatin Rivers.


The Underground Injection Control (UIC) Permit covers stormwater facilities that discharge stormwater to groundwater with no filtering process (e.g. drywells, infiltration trenches, infiltration galleries).

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