The City of Lake Oswego operates a surface water management utility that includes ”all natural and man-made facilities utilized by the Surface Water Utility to regulate the quantity and quality of surface water, including drainage easements, culverts, storm drains, catch basins, stream corridors, rivers, ponds, wetlands and impoundments.” The goal of the program is to reduce pollutants to the maximum extent practicable (MEP).
The City of Lake Oswego’s stormwater system is not connected to the City’s wastewater system. As a result, much of the stormwater enters receiving waters untreated. Stormwater and other “nonpoint source discharges” (NPS) are regulated by the 1972 Federal Clean Water Act through the National Pollutant Discharge Elimination System (NPDES) permit program. The State of Oregon Department of Environmental Quality administers this permit program in Oregon for the United States Environmental Protection Agency (USEPA).
The Federal Clean Water Act and the State of Oregon mandate that the City of Lake Oswego be issued a NPDES Phase I municipal stormwater (MS4) permit. The City of Lake Oswego shares a permit with twelve other jurisdictions in Clackamas County. Stormwater is also regulated when it discharges to Underground Injection Control features (usually dry wells). More detail is found in the "Stormwater Program" section below. The City must also implement total maximum daily load requirements for the Tualatin and Willamette River basins, as described in the "Total Maximum Daily Loads" section below.
Links to the MS4 permit document and TMDL documents issued by DEQ, as well as City plans and reports prepared as required by these documents, are found on Permits, Plans, and Reports page.