Conduct PHearing_Flood Mitigation_Whiskey Creek

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PROJECT NARRATIVE Project Purpose In 2020, the Kittitas County Flood Control Zone District produced its first six -year Capital Improvement Plan (CIP) for the 2021-2026 period. This CIP, and each subsequent annual update, has included the Whiskey Creek at Ellensburg Water Company Siphon Project. The project was included because it is necessary to decrease flooding along Whiskey Creek. Of central concern to flood management goals in this area is addressing the flood impacts across Bender Road, a Kittitas County road that serves as the main east -west corridor northwest of the City of Ellensburg within the Urban Growth Area (Figure 1). Bender Road, from Mile Post (MP) 0.00 to MP 0.59, is classified as an Urban Collector. It has an Average Adjusted Daily Traffic (AADT) count of 2,633 vehicles, with 16% truck traffic. The estimated annual gross tonnage is 1,005,000, placing it in Truck Route Class T3, representing a high -volume freight route. The Ellensburg Water Company (EWC) Canal (also known as the Town Ditch) provides irrigation water to approximately 10,000 acres throughout the Kittitas Valley. Water diversion by the EWC dates back to 1885. Consistent with practices at the time, the canal was constructed over the tops of creeks, with creek conveyance accomplished by routing the creek under the canal. At the location where the EWC canal intersects Whiskey Creek, the creek is piped under the canal through a culvert (Figure 2). However, the culvert does not have adequate capacity to convey flows during high-water events, causing water to back up behind the canal. The proposed EWC siphon project will replace this configuration by placing a segment of the canal in a siphon routed beneath Whiskey Creek. The Whiskey Creek at Ellensburg Water Company Siphon Project works in conjunction with flow conveyance improvements at the upstream Bender Road crossing of Whiskey Creek to address flooding issues. The previous culvert at this location was replaced with a bridge, increasing water conveyance capacity. However, due to flooding concerns caused by limited conveyance at the downstream EWC canal siphon, a metal flow restrictor plate was installed to limit the amount of water flowing through the bridge (Figure 3). Because of this restricted conveyance, water is more likely to travel west and overtop Bender Road. As a result, Bender Road has been closed due to flooding on a nearly annual basis. The intent of this project is to reduce flood -related closures of Bender Road. Acquisition Need The project requires a temporary construction easement for 24,501 square feet of property on parcels 962710 and 962712, and a right-of-way acquisition for 9,230 square feet on parcel 962710.