The recommended plan will convey design outflows of 30,000 cu. ft/s from Prado Dam to 47,000 cu. ft/s at the Pacific Ocean. The project consists of acquisition of the post project overflow area along 8 miles of river just downstream of PRado Dam (Prado Dam to weir Canyon Road) and 23 miles of improved channel (Weir Canyon to the Ocean). The reach from Prado Dam to Weir Canyon would remain in a natural rural condition for wildlife and open space value. The improved channel will consist of sections of trapezoidal riprap or grouted riprap channel, trapezoidal concrete-lined channel and rectangular concrete-line channel. The ocean outlet will consist of rock mounded jetties. In addition, the Greenville-Banning Channel would be modified to join the Santa Ana River about 1 mile upstream of the Pacific Ocean. Talbert Channel will be relocated 1,000 feet upcoast from its present location to accommodate relocated 1,000 feet upcoast from its present location to accommodate widening of the Santa Ana River at the ocean. the channel access and maintenance roads would be incorporated into the overall recreational trail system for the entire river. a 92-acre marsh will be restored at the mouth of the river for the preservation and enhancement of wildlife. (FR).

This volume contains hydrologic information in support of the general design consideration for Seven Oaks Dam, Prado Dam, Santa Ana River mainstem between Seven Oaks Dam and Prado Dam, Mill Creek levee, Oak street Drain, Santiago Creek, and lower Santa Ana River. (FR).

The recommended improvement to the existing flood control Prado Dam, which was completed by Corps of Engineers in 1941, consists of enlarging the reservoir capacity by raising the spillway crest 20 feet and the top of the dam 28.4 feet to elevations 563 and 594.4 feet, respectively. A new gated outlet structure capable of releasing 30,000 cubic feet per second, an auxiliary dike, and a dike along the Corona Expressway would be provided. Approximately 1,660 acres of land up to elevation 566 feet would be acquired for the enlarged reservoir. Interior dikes would be provided for the protection of the existing facilities at the Corona Sewage Treatment Plant, Alcoa Aluminum Plant, Corona Housing Tract, and California Institution for Women. The cost for the recommended improvement is estimated at $212,623,000, including $116,274,000 for land acquisition. (fr).

Contents: Geotechnical; Coastal Design; Sediment Transport Analysis; Recreation; Side Drain Tabulation (Storm Peak Discharges). (FR).

The recommended plan for Oak street Drain consists of a concrete channel beginning at the existing Oak Street debris basin and extending over 3 miles to the confluence with Temescal Wash. The channel is designed to provide 100-year level of protection. Total project first cost is estimated at $20,652,000. The economic data for the project is contained in Volume 9, 'Economics and Public Comment and Response.' (FR).