September 20 2019
After the great Willamette Valley Flood of 1996, which devastated Lake Oswego and many other cities in late January and mid-February 1996, Lake Oswego city planners decided it was time for a dam.
The basic idea was to control the flow and release of water out of Lakewood Bay. Water in Lakewood Bay originates from the Tualatin River and the larger lake called Lake Oswego. During high water levels or during a food, the plans called for the control of water flow from Lakewood Bay to the Willamette River a quarter mile downhill to the east.
City planners also decided it was time to improve the 40-year-old sewer systems in and around the lake with what is called the Lake Oswego Interceptor Sewer project. "It was an opportune time," said David Donaldson, director of emergency management for Lake Oswego. "We couldn't do it when the lake was up. Now it's going to be rising 1½ feet a week."
The huge $90 million construction of Oswego Lake Dam at Lakewood Bay is a prime example of two good plans merging into one. The damn, neatly coined, "The Oswego Lake Dam Spillway Modification Project", is in the final stages of being completed. Homeowners around the lake are happy because flood insurance rates should dramatically decrease once the construction is completed.
"The dam will now allow much more water out much quicker, Donaldson said. "The whole dam structure is being modernized."
The flood of 1996 not only threatened Lake Oswego but seriously damaged the navigation locks at Willamette Falls. In Portland, water levels from the Willamette River rose to about an inch below boardwalk sidewalk levels before receding. A few more inches and downtown Portland would have been badly flooded.
Lakewood Bay in Lake Oswego, fed by the larger Lake of Lake Oswego, rose dramatically during the food, ran over State Street, flooded US Bank and other businesses and homes, and ran down the Foothills area to the Willamette River. Along the way, streets, roadways, and sidewalks were torn to pieces, ripped to shreds, and apartments and homes were flooded and heavily damaged.
Memories of the great flood of 1996 make the completion of the dam project great news for many Lake Oswego residents.
For the project, FEMA provided a grant of nearly a million dollars and Lake Corp spent $200,000 for engineering costs.
Water levels in Lakewood Bay were lowered by 24 feet for contruction. Now water levels are nearly back to normal. The last concern before the project can be called successful is to see if the installed damn system actually works. Final testing will begin after Lakewood Bay refills to normal level.
Photo 1: Downtown Lake Oswego flood, 1996. Photo courtesy of City of Lake Oswego