West Magnesia Canyon Channel, City of Rancho Mirage, Riverside County, California. Detailed Project Report. Rancho Mirage Flood Control. Technical Appendixes

Book excerpt: West Magnesia Spring Canyon Creek, which originates in the SantaRosa mountains, skirts the western side of Rancho Mirage along the foothills as it leaves the canyon and flows a distance of about 1.5 miles before it empties into the Whitewater River. The drainage basin comprises about 5 square miles. The main objectives of this study are to provide a high degree of flood protection to the residents of Rancho Mirage and to protect the Nation's environment. The Corps recommends that, subject to certain conditions of nonFederal cooperations outlined in this report, the proposal for flood control be approved for construction. The total cost of the recommended plan is estimated at $8,279.000. The Federal share of the estimated cost would be $4,000,000, and the non-Federal share of the estimated cost would be $4,279,000 of which $3,891,000 is for construction and $388,000 is for lands, easements, rights-of-way and relocation. The local sponsor of the project is the Coachella Valley Water District. In order to safely convey the standard project flood (SPF) through the community of Rancho Mirage, the project would consist of the following major elements: Inlet structure and debris basin; spillway chute and transition; approxiately 5.500 feet of concreted-lined rectangular channel; and an outlet energy dissipator. The basis for the design of this project is founded on approved design practice and on theoretical analysis.