About the Project


The historic First Addition Neighborhood (FAN) of Lake Oswego suffers from chronic localized flooding, deteriorating roadways and minimal pedestrian amenities.

The 2009 First Addition Neighborhood Drainage Report identified several projects throughout the neighborhood necessary to address inadequate stormwater infrastructure, help alleviate areas of localized flooding and to provide direction to the City towards meeting regulatory water quality requirements.

The rehabilitation of D Avenue was an identified next step which built upon other recent street rehabilitation projects, including A Avenue and B Avenue.

Project Scope

The D Avenue Improvement Project addresses stormwater drainage issues, pedestrian access and safety, and poor pavement conditions on D Avenue from State Street to 10th Street.

The project reconstructed the entire ten blocks of D Avenue from State Street to 10th Street, all within the existing public right-of-way. Additional improvements included stormwater, waterline and pavement work on 1st Street between D/E Avenues. A new stormwater pipe on 7th Street between B/D Avenues. The area bounded by 8th/9th Streets and D/E Avenues also received stormwater improvements, including a new pipe and planters/rain gardens, and new pavement.

The design incorporates a much safer way for pedestrians to connect to schools, downtown businesses, the library and other services in the neighborhood. It also helps address significant stormwater issues and rebuilds old, deteriorated underground utilities in this area of the neighborhood.

Final Components

Two neighbor walking tours, two public open houses, numerous face-to-face meetings and extensive field work helped inform the designs of the project. The project included full reconstruction of the road, a new sidewalk, and new stormwater management above ground and below.

Features include:

  • Portions of the new road alignment meander with slight curves.

  • The newly built road has two travel lanes and is approximately  20’ wide, similar to the width of the previous roadway.

  • Some areas in the right-of-way have 7’ wide delineated gravel parking.

  • New sidewalk was added along the north side of D Avenue, west of 5th. 

  • The existing sidewalk was rebuilt on the south side of D, east of 5th Street.

  • Low-level pedestrian lighting was added to illuminate the sidewalk.

  • About 40 new rain gardens (just over 23,000 square feet) were installed at key locations along D Avenue, and 5,500 feet of upgraded stormwater pipes help manage street runoff.

  • Stormwater facility markers were installed to help identify each facility. These correspond to a new informational kiosk  that was also installed, at the corner of D and 4th.

Additional sample renderings and a map of the final designs are available to view on the materials page.

Project Goals and Benefits

  • Reduce localized flooding
  • Improve treatment of stormwater runoff and drainage
  • Provide a safe pedestrian passage
  • Improve driving surface on D Avenue

The project benefits Tryon Creek and improves areas in the neighborhood that experience flooding or drainage issues. The project also included pedestrian improvements to provide walking connections within the neighborhood, providing safe, American Disabilities Act (ADA) compliant pedestrian passage for school children, residents visiting the library and those choosing to visit downtown businesses.

Learn more about how the project was built by visiting the project updates page.

Designing for stormwater, pedestrian, and pavement needs