Environmental statement: San Luis Rey River, San Diego County, California

25 SEPTEMBER 1970 ENVIRONMENTAL STATEMENT SAN LUIS REY RIVER, SAN DIEGO COUNTY, CALIFORNIA PREPARED BYU. S. ARMY ENGINEER DISTRICT, LOS ANGELES, CALIFORNIA25 September 1970 SAN LUIS REY RIVER, SAN DIEGO COUNTY, CALIFORNIAENVIRONMENTAL STATEMENT Project Description. The San Luis Rey River flood control project would provide flood protection in the lower San Luis Rey Valley where urban development is taking place, would eliminate the need for filling that otherwise would be required for development, and would permit increased utilization of property by (a) accelerating the growth of industrial and commercial developments on 373 acres and (b) permitting residential use on about 667.5 acres. The recommended channel improvement, which would be approximately 7.2 miles long, would include: (a) An earth-bottom trapezoidal channelabout 5.7 miles long from Murray Road to about 1 mile upstream from U.S. Highway No. 101; (b) about 1.5 miles of channel grading, which in general would be limited to the removal of spoil banks from a point 1 mile upstream from U.S. Highway No. 101 through the "Narrows" section, to the ocean; and (c) about 800 feet of stone-revetted levee on the left .(south) bank of the San Luis Rey River from the Santa Fe railroad to the ocean. The earth-bottom trapezoidal channel, with stone-revetted side slopes, would have a base width of 400 feet. The entrenched channel would average about 19 feet in depth, with levees on the average of about 9 feet above the existing adjacent ground line. Channel invert stabilizers, located about every 2,000 feet, and one concrete drop structure would be con­structed to control the invert slopes and to minimize streambed erosion. Work within the "Narrows" area would be limited to the removal of spoil banks to reduce the backwater effect at the lower end of the proposed channel. Vegetation and ponds within this reach would be left in place and the area would be made available to the California Department of Fish and Game for wi