Ada County Highway District

ACHD Supporting Ada County, Cities along the Boise River with Flood Response

Plantation Island Bridge Tree Removal.jpgThe continued, high flows of the Boise River create concerns about potential major flooding, particularly from the Glenwood Bridge to the Canyon County line. The District is working with Ada County, Boise City, Garden City, Eagle, Star and the Ada County Sheriff's Office to respond to the crisis, which is expected to last into July.

Ada County has taken the lead on the response, and a flood team from the U.S. Army Corps of Engineers arrived on April 4, 2017 to lend assistance with a potential problem that could reroute the river and send water into neighborhoods around Eagle Island. Eagle and Linder roads also could be closed if the so-called "pit capture" event plays out, as detailed in this release from the Corps. The levy work was completed on April 12th.

The river is running around 9,000 cubic feet per second, or cfs, as measured at the Glenwood Bridge. The flow is above the 7,000 cfs which is officially flood stage, and could go higher depending on how quickly the snowpack melts.

ACHD hauled riprap to the Eagle Island area to be used to shore up the berms separating an area of gravel pits from the river. On March 31, 2017, District crews cut back trees near the imperiled Plantation Island Greenbelt Bridge near the Expo Idaho stables to allow a mobile crane to remove the bridge, which was in danger of falling into the river because of erosion of its abutments.

In an abundance of caution, ACHD is working with its local government partners to create road detour plans to be used in a major flooding event, whether that be even higher river flows, the pit flooding or some other scenario. Officials urge residents of the Eagle Island area to be prepared because there may be only 12 hours or less lead time during flood evacuation.

Residents living near the river are encouraged to stay informed and make preparations to act. The county's Code Red system will allow citizens to receive alerts in an emergency.


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