Drivers: Prepare for a full closure of State Route 900/Renton-Issaquah Road Southeast near Issaquah from July 28-31, 2017.
Starting at 7 p.m. July 28, SR 900 closes for a Washington State Department of Transportation (WSDOT) fish passage project. The road will reopen to drivers by 5 a.m. July 31.
Even though the highway will be closed all weekend, you'll still be able to use it between Issaquah and Renton.
WSDOT will have a signed detour set up via 164th Avenue Southeast, Southeast 128th Street/Northeast Fourth Street and Duvall Avenue Northeast (see map).
During the closure, crews will replace the culvert for Green Creek, west of 164th Avenue Southeast.
Green Creek is about 11 feet wide, but as it flows under SR 900, it travels through a narrow 4-foot-by-3 foot culvert. The narrow opening forces the water through the culvert at a high rate of speed, making it harder for fish to pass through.
Contractor crews working for WSDOT will remove the old culvert and replace it with a 16-foot-by-10 foot culvert.
SR 900 is two lanes wide with almost no shoulder at Green Creek, and carries about 9,500 vehicles a day. However, the culvert is more than 25 feet beneath the road, so it will take crews an entire weekend to dig out the old culvert and replace it with new culvert.
Once the new culvert is in place, crews will fill in the gap, repave SR 900, replace the guardrail and reopen the highway.
With the new culvert in place, crews will be able to create a natural creek bed in it, making it much easier for salmon, trout and other species to travel upstream.
A 2013 U.S. District Court injunction requires WSDOT to replace certain types of culverts under state highways.
To learn more about the Green Creek fish passage and sign up for updates, go to WSDOT's project website.