Portland District

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Spillway gates issues

graphic showing structural problemsOur Dam Safety program has found that most of our dam’s spillway gates are aging and may not operate properly when water levels are high and placing significant pressure on the gates. This may result in a gate failing to open, or becoming stuck in the open position. Such failures could compromise our ability to manage water releases from that dam.

 

We assessed the gates in 2010, which resulted in the replacement or repair of critical components and development of a prioritized plan for long-term rehabilitation of the gates.  All of Green Peter, Foster, Big Cliff, Lookout Point, Dexter and Fall Creek dams' spillway gates have been strengthened.  Rehabilitation of Blue River and Hills Creek dams' gates are in progress and scheduled for completion in Fiscal Year 2018. The need for longer term gate rehabilitation work remains at four dams in the Willamette Valley.

 

For more information about the Willamette Valley dams’ gates, see:

Willamette Valley spillway gates: Posters
Willamette Valley spillway gates: Repair status
Willamette spillway gates: YouTube video

Water level impacts

gate tracking diagramWe are reducing the risk of uncontrolled releases while continuing to provide flood reduction support through the winter.  We have lowered the pool elevations at which spillway gates need to be opened, to reduce pressure on the gates and the potential for their failure.  This in turn means the dams may need to release water earlier during flood events, leading to higher than usual downriver flows.

Click here for the pool elevations at which we must open spillway gates at each dam.

We intend to operate the projects much the same as in any other flood season.  However, the gate operating restrictions may mean increased water releases from our reservoirs during severe rainstorms or a series of storms.  The public downstream of our dams may see releases up to bankfull more often and for longer periods of time during and following storm events, as we work to lower the reservoir back to pre-storm levels in order to provide storage for future storms.

For current and projected Willamette reservoir and river elevations and flows, visit:

http://www.nwp.usace.army.mil/Missions/Water.aspx

http://www.nwrfc.noaa.gov/rfc/

Be prepared

We urge property owners and those living and working near the rivers to understand their level of risk and take preparedness actions.  For virtually all emergencies, county emergency management offices are the first sources of information, the first responders, and the designated authorities for deciding upon and announcing evacuations:

 Counties can declare emergencies and request support from the State of Oregon.  If the emergency is of sufficient magnitude, the state may request federal assistance, including Corps emergency response.

People should always remain aware of the dynamic nature of water and storms.  Relying on dams isn’t a substitute for smartly managing one’s property and being prepared for an emergency.  Flood preparation and insurance information is posted at FEMA’s FloodSmart website: http://www.floodsmart.gov.