Manastash Creek at Cove Road, May 2011 Post Flood Investigation & Flood Relief Opportunities

External Document

Date published: December 21, 2011

Authors: Watershed Science & Engineering

Reference:

Watershed Science & Engineering. 2011. Manastash Creek at Cove Road, May 2011 Post Flood Investigation & Flood Relief Opportunities. Prepared for Kittitas County, December 21.

Abstract:

On May 15 and 16, 2011 a large flood on Manastash Creek near Ellensburg, Washington caused significant damage to a home, outbuildings, roads, and agricultural fields at and downstream from the Cove Road Bridge over Manastash Creek (Figure 1). Most of the damage was caused by water that overtopped the north bank upstream from the bridge, flowed through a residential lot, crossed Cove Road, and then flowed overland down the surface of the Manastash alluvial fan. To stop the flooding private citizens mobilized multiple excavators to remove material from the stream and build flood protection berms along the north bank upstream and both banks downstream from the Cove Road Bridge. The berms remain in place today. Because the berms were constructed as an emergency, no floodplain development permits were obtained from the County. A permit is required when features are built within a known flood hazard area because the County is responsible to make sure the project adheres to all local, state, and federal floodplain development requirements. One key floodplain development requirement is that a project cannot increase water levels nor otherwise adversely impact adjacent or downstream property owners. Unfortunately, because the berms prevent flow from leaving the channel, properties that border Manastash Creek downstream from Cove Road will likely be impacted.

Kittitas County desires to work with local property owners to develop a collective and reasonable plan to reduce flood risk and determine what to do with the existing berms. To aid in this effort, Kittitas County has asked Watershed Science and Engineering (WSE) to provide specialist river engineering services to determine what caused the flooding in the vicinity of Cove Road and to identify actions that may provide flood relief for local residents. This report presents the results and recommendations of WSE’s investigation.

Contact person/agency: Kittitas County

File Format: pdf

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