Wind
Humidity
Seattle Port Lagoon No 3 Expansion is a critical flood risk reduction project located in King County, Washington.
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 |
| Location | Reservations | Toilets |
|---|---|---|
Point Robinson Campground
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Dash Point State Park
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Dash Point Campground
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Cascadia Marine Trail
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Gig Harbor RV Resort
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Manchester State Park
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Seattle Port Lagoon No 3 Expansion
Des Moines Ck Reg Det Pond West Berm
Des Moines Creek Stormwater Detention Da
Des Moines Ck Reg Det Facility East Berm
Seatac Airport Se Pond
204th Street Stormwater Detention Basin
Lake Tapps Near Sumner
Sammamish Lake Near Redmond
Cedar Lake (Masonry Pool) Near Cedar Falls
Howard A Hanson Reservoir Near Palmer
Mud Mountain Lake Near Buckley
Chester Morse Lake At Cedar Falls
Snoqualmie Falls to Plum's Landing
Confluence With Taylor River To Confluence With North Fork Snoqualmie River
Wagner Bridge To Confluence With Middle Fork Snoqualmie River
Huckleberry Creek To Confluence With Clearwater River
Brothers Wilderness Boundary To Olympic Nf Boundary
Quartz Road To Confluence With Middle Fork Snoqualmie River