Stormwater Management Manual

The City’s Stormwater Management Manual (SWMM) provides guidance and standards for the placement, design, and maintenance of structures used to control runoff, reduce flooding, and prevent pollution from contaminating our local waterways. The manual applies to stormwater management design for public and private development and redevelopment within the City of Lake Oswego.

Stormwater Manual Now Open for Public Comment - NOW EXTENDED through May 30

We are revising the manual to incorporate stakeholder feedback and revised requirements from the Department of Environmental Quality. Major updates include:

reordering of the manual on some core content,
removing educational information that didn’t relate to design,
adding facility hierarchy table/criteria required by the new permit,
changing how offsite discharges are treated.

The revised manual is available for public comment through May 30. Review this document to see the manual's reorganization, including a list of frequently used tables from the 2020 version.