Seattle Port Lagoon No 3 Expansion is a critical flood risk reduction project located in King County, Washington.
Wind
Humidity
Owned by the local government and regulated by the Washington Department of Ecology, this expansion was completed in 2001 by Kennedy-Jenks Consultants. The dam, primarily constructed of earth and rockfill, stands at a hydraulic height of 31.5 feet and has a storage capacity of 256 acre-feet, with a normal storage level of 221 acre-feet.
With a surface area of 0.9 acres and a maximum discharge of 140 cubic feet per second, this project plays a key role in managing flood risks in the region. The dam's hazard potential is classified as high, but its condition assessment in 2018 deemed it to be in fair condition. The dam undergoes inspections every five years, with the last inspection taking place in May 2017. Despite its importance in flood risk reduction, there are no associated structures or outlet gates in place.
Overall, the Seattle Port Lagoon No 3 Expansion serves as a vital infrastructure for protecting the surrounding areas from potential flooding events. Its strategic location along Des Moines Creek - Offstream and its compliance with state regulations highlight its significance in water resource management and climate resilience efforts in Washington state.
Years Modified |
2000 - Hydraulic |
Year Completed |
2001 |
River Or Stream |
Des Moines Creek - Offstream |
Primary Dam Type |
Earth |
Surface Area |
0.9 |
Hydraulic Height |
31.5 |
Nid Storage |
256 |
Structural Height |
31.5 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
32 |
Mill Creek Near Mouth At Orillia
|
44cfs |
Spring Brook Creek At Orillia
|
7cfs |
Duwamish River At Golf Course At Tukwila
|
6700cfs |
Mill Creek At Earthworks Park At Kent
|
8cfs |
Cedar River At Renton
|
5160cfs |
Green River Near Auburn
|
10100cfs |
| Location | Reservations | Toilets |
|---|---|---|
Point Robinson Campground
|
||
Dash Point State Park
|
||
Dash Point Campground
|