Ada County is making a final effort to protect a gravel pit on Eagle Island, installing a 600-foot “muscle wall” between the Boise River and the farm field next to the pit.
The wall is 2 feet tall and is directly beside the 4,000-foot temporary levee installed by the U.S. Army Corps of Engineers and the 600-foot flood diversion tube put in by Ada County last month, according to the Eagle Police Department.
The tube is near the head of Eagle Island to bolster an area where swift water has eroded sections of the riverbank. So now there is a physical barrier between the river and the pit stretching all the way to the Garden City border at Duck Lake Drive.
The privately owned gravel pit is near the east end of Eagle Island, not far from the Island Woods and Two Rivers neighborhoods. Officials have been worried that if that area floods, it would change the course of the river and send water in directions experts can only guess.
Ada County crews also installed a new drainage ditch in the farm field next to the gravel pit that will move any water to a nearby pond, where it will be pumped back into the river.
This is essentially the last possible effort to prevent flooding in that area as the Boise River continues to rise. By next week, the river flow is expected to increase to 9,500 cubic feet per second, its highest level since 1983.