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.