Roads and flooding
Which roads are most prone to flooding in our service area?
The Snoqualmie Valley is most prone to flooding when heavy rain or snow melt occurs. This flooding causes roads to be closed – in some cases for long periods of time. This page includes detailed information about how we respond.
Which roads typically flood?
- 308th Avenue SE from State Route 202 to SE 31st Street
- 310th Avenue NE between NE Carnation Farm Road and NE 60th Street
- 324th Avenue SE from Highway 202 to West Snoqualmie River Road NE
- NE 100th Street (Adair Road) between NE Carnation Farm Road & West Snoqualmie Valley Road NE
- NE 124th Street between West Snoqualmie Valley Road NE and State Route 203
- NE 60th Street between 310th Avenue NE and State Route 203
- NE 80th Street between West Snoqualmie Valley Road NE and Ames Lake Carnation Road NE
- NE Tolt Hill Road between State Route 203 and West Snoqualmie River Road NE
- Neal Road SE between State Route 203 & State Route 203 (end to end)
- SE 24th Street between 309th Avenue SE and West Snoqualmie River Road SE
- SE 44th Place (Dike Road) at Preston Fall City Road eastbound to end
- SE David Powell Road from SE Preston Fall City Road to end
- SE Fish Hatchery Road between SE 49th Street & 372nd Avenue SE
- West Snoqualmie River Road NE between NE Tolt Hill Road and SE 24th Street
- NE 165th Street between 179th Place NE and Avondale Road NE
Why were roads built in flood areas and why can’t we stop them from flooding?
Many of the major roads in the Snoqualmie Valley were constructed in the nineteenth century. Roads were typically built adjacent to rivers and followed property lines. Many of these roads will always be vulnerable to flooding because of geography and the historical drainage patterns that existed long before these roads were constructed. Raising roadways can cause the roads to act as natural dykes or dams that cause damage further upstream – ultimately the water needs to drain into Puget Sound. The fix to some of these problems is to build trestle bridges across the valleys - projects that would cost tens of millions of dollars.
How does Road Services respond to severe weather and flooding?
Before severe weather hits, King County staff shift into emergency response mode. Field crew work shifts are changed from their normal daytime hours to two 12-hours shifts that allow for around the clock storm and safety response in unincorporated King County. The 24/7 Road Helpline is staffed with more customer service agents to perform call intake and rapid deployment of the storm safety related incidents being reported. Communications teams monitor and report significant incidents such as road closures via the King County My Commute map. Road Alerts and Twitter are used to relay information about unincorporated roadways affected by severe weather.
In case of flooding:
- To report roadside flooding, call the 24/7 Road Helpline at 206-477-8100
- If you are caught in your home or car by rapidly rising waters, call 911 immediately
- Do not walk or wade through flooded areas
- Do not drive where water is over the road or around barricaded road signs
When sloped areas become completely saturated by heavy rainfall, the risk of slides increases. While the likelihood of slides begins to decline after a day or more of dry weather, some deep-seated slides may occur days or even weeks to months after long periods of intense rainfall. Residents near mountain slopes, canyons, and slide prone areas should stay alert even after heavy rain subsides.
The King County Office of Emergency Management provides additional slide information including hazard-specific preparedness steps and response steps.