One Voice Lewis County
One Voice Lewis County – Fighting for a Chehalis Basin solution Since 2007
Flood Retention Facility
A main focus in the Chehalis Basin Strategy is to reduce damage from catastrophic flooding. The measures already underway include raising homes, buying out frequently flooded properties, working with governments in the basin to assure that local land use policies reduce the risk of future damage. In addition to these actions, a water retention structure on the main stem of the Chehalis River above Pe Ell has been proposed. A Flood Retention Only – Expandable (FRE) facility type has been recommended by the Chehalis River Basin Flood Control Zone District Board of Supervisors. Two separate Environmental Impact Statements (EIS)are being prepared by the US Army Corp of Engineers and the WA Department of Ecology. The EISs are expected to be complete in 2020.
FLOOD RETENTION ONLY – EXPANDABLE (FRE)
This type of facility is designed to temporarily hold back water during major floods; there would not be a permanent pool of water. The river would flow normally during regular conditions or smaller floods. The facility is considered expandable because it would be constructed with a special foundation that could allow future generations the ability to expand the water retention capacity of the facility and, if found to be beneficial, augment stream flows. There may never be a need to expand the capacity. This solution was proposed in an effort to address the uncertainty in the climate and hydrology of the future. Future expansion of the facility would need to be completed with the required environmental review, permitting, and design details taking into account the best available science at that time.
Read the Draft Created by the State of Washington Dept of Ecology
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John Henricksen, Advisory Committee Chairman to the Flood Zone District, provided a report covering key points on the DRAFT EIS. Please read before you leave a comment.
Links to Supporting Documents
Washington State Department of Ecology’s SEPA EIS:
The following studies and reports have been submitted for consideration as part of the record:
Operations Plan for Flood Retention Facilities, Anchor QEA, 2017
Combined Dam and Fish Passage Supplemental Design Report, FRE Dam Alternative, HDR Inc., 2018
Lewis County Recovery Strategy, Lewis County, 2009
Governor’s Chehalis Basin Work Group Recommendation Report, Ruckelshaus Center, 2014
Centralia, Washington Flood Damage Reduction, United States Army Corps of Engineers, 1982
Multi-Purpose Water Storage Assessment, Tetra Tech and Triangle Associates, 2003
Chehalis River Flood Water Retention Project Phase IIB Feasibility Study, EES Consulting 2011
Chehalis Basin Flood Hazard Mitigation Alternatives Report, The William D. Ruckelshaus Center, 2012
Chehalis River Basin Flood Reduction Project, Pacific International Engineering, 1998
FRO FRFA Final Conceptual Combined Dam Fish Passage Design Report, HDR Engineering Inc, 2017