Ada County flooding leads to new emergency measures, closes another Greenbelt section

Local municipalities and the U.S. Army Corps of Engineers issued another disaster declaration, closed another section of the Greenbelt and activated new emergency measures on Tuesday to handle the ongoing flooding from the Boise River.

A four-member U.S. Army Corps of Engineers emergency management flood-fight team deployed Tuesday to Boise to help Ada County. The team came from the Corps’ Walla Walla District.

Last week, the Corps provided technical experts to assess potential consequences of river water seeping through the shoreline and into adjacent gravel-mining pits along the Boise River, near Eagle Island.

Sinkholes were found as a result of flowing water in the gravel pit. Bank sloughing along two of the pits also indicated bank instability, according to a news release from the Corps. If the river bank fails, it could lead to a pit capture — a term used to describe river water diverting into the pits. That could reroute a significant portion of the current river flow in an unknown direction, along the south channel near Eagle Island.

Any rerouting would potentially put lives, property and infrastructure at risk, including the Boise wastewater treatment plant and road access.

The U.S. Army Corps of Engineers and other federal dam managers have released more water than usual into the Boise River in a bid to avoid worse possible flooding as temperatures rise this spring and swollen mountain snowpacks melt. The river has been above flood stage, as measured at the Glenwood Bridge, since early March.

Flooding and other problems caused by high Boise River flows have closed several sections of the Greenbelt over the last month, mostly recently near Veterans Memorial Park, according to a Boise Parks and Recreation press release on Tuesday afternoon.

Garden City Mayor John Evans on Tuesday announced he would join the city of Boise and Ada County in declaring a state of emergency due to the high water levels on the Boise River. The Canyon County Commission also declared a local flood emergency on Tuesday in its county.

Evans directed residents to the Ada County Emergency Management flood response plan in case emergency evacuation is necessary.

The Boise Fire Department has posted a “dangerous river conditions” warning for the length of the river running through the city. Officials ask that people stay away from the river and avoid using the Greenbelt until conditions become more predictable.

The newest Greenbelt closure starts on the north side of the Greenbelt right before the tunnel under Veterans Memorial Parkway. The closure extends to Lander street. Parks and Rec officials say there is no detour currently available.

Greenbelt closures

The Veterans Memorial Park closure joins eight other closures along the Greenbelt in Boise. They are as follows:

• Mile marker NW 3.7 to about NW 4.0 just west of Willow Lane Athletic Complex
• Under the West Parkcenter Bridge at Logger Creek
• The entire Bethine Church River Trail
• Section of Greenbelt and a gravel nature path near Marianne Williams Park between East ParkCenter Boulevard and South Eckert Road.
• Section of Greenbelt near Marianne Williams Park at the bridge over Walling Creek, which is south of E. Warm Springs Avenue.
• The boardwalk under the Capitol Boulevard Bridge on the south side of the Greenbelt
• Section of Greenbelt from Main Street Tunnel to Trestle Bridge on north side of the Greenbelt
• 9th street tunnel on south side of the Greenbelt

In addition, a section of the Greenbelt behind Cottonwood Grille is closed to remove trees damaged by the wet weather. On Monday, crews removed a bridge connecting the Greenbelt to Plantation Island in Garden City after high river flows damaged that structure as well.

The city of Eagle has closed the following sections of the Greenbelt:

• The underpass under Eagle Road on the North Channel of the Boise River
• The entire unpaved trail north of Laguna Point Subdivision
• The Mace Trail from Eagle Road to about 1Z4 mile west
• The west end of Mace Trail for approximately 150 yards
• An unpaved alternate route near the Greenbelt, at Eagle River Apartments, that normally reconnects near the River District Subdivision

This story was originally published April 4, 2017 at 2:11 PM with the headline "Ada County flooding leads to new emergency measures, closes another Greenbelt section."