Crews watching for dangerous downed trees in Boise River

Downed trees in river could cause flooding.

BOISE -- As river banks slough away and flows remain swift, officials are concerned about the possibility of trees breaking loose and toppling into the Boise River.

Add this to the list of hazards that city officials and road crews are monitoring: downed trees creating a dam effect against bridges, possibly causing significant flooding.

Last week - after strong gusts of wind ripped through the Treasure Valley - crews were out between Capitol Boulevard and Americana Boulevard recovering seven trees that had fallen into the river.

Fortunately, they were able to remove the downed trees from the water before they caused an even bigger issue.

RELATED: Boise mayor: Stay away from Boise River, Greenbelt

It is an effect of a dangerous combination of saturated and eroding river banks, high, fast flows, and strong winds. Those factors can uproot trees and break off limbs,  which then go toppling into the water.

"A pretty serious flooding incident can occur very quickly," Ada County Highway District Chief Information Officer Craig Quintana, said.

Localized flooding could occur if trees that crash into the water end up pushing against bridges.

"Those would be the obvious pinch points where if you get a tree down with branches it becomes a strainer, picks up more material and then within minutes you can have a dam," Quintana added.

Right now - and for the last several weeks - the distance between bridges and the rushing water is much smaller.

"If you did get something snagged up against a bridge you could have a really bad flooding incident - very intense and very quickly occurring," Quintana said.

"[Water] can go on the roads, it could go whatever is nearby: a business or a home could start to be flooded," Boise Fire Chief Dennis Doan told KTVB.

None of that has happened yet, but crews from across Ada County did retrieve downed trees in the raging Boise River last week after a strong storm hit the area.

"Right now it's washed all the debris down so now we're just worried about trees that are standing that could fall over," Chief Doan added.

Transportation officials, emergency responders, local parks and recreation departments and forestry department are all working together to monitor the span of the river on a daily basis.

"Pretty much every span is being looked at every two hours, if not more often," Quintana said.

ACHD says their crews are removing trees safely using backhoes or trackhoes.

"Knowing that it's kind of dicey work, you go in with an extra amount of vigilance and be mindful of safety," Quintana added.

Officials say concerns over fallen trees contribute to the reasons why Eagle, Garden City and Boise shut down the Greenbelt.

"There's lots of washouts underneath the Greenbelt and that's why it's so hazardous. And really, another reason why we closed the Greenbelt was because so many trees are falling over and have to be removed. And it could fall on somebody," Chief Doan said.

RELATED: Boise, Garden City Greenbelt closures shut down most of pathway

 

With only 11 miles of the nearly 50-mile stretch of Greenbelt t now open in Ada County, officials are urging you to stay off the path. The Greenbelt is eroding more and more every day, plus there is very little connectivity with all the standing water up and down the pathway.

In addition, Chief Doan says you can be charged if emergency responders have to rescue you from the river because it puts their lives at risk.

© 2017 KTVB-TV


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