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Rito Seco FER Alternative ~l: 3 A reservoir was considered, but would be limited by the steep gradient of the Rito Seco. The estimated cost of a reservoir controlling approxi- mately 80 percent of the drainage area would be about $4,500,000. The average annual cost would be about $285,000. Average annual benefits accruing from Alternative ~l would be about $78,000 resulting in a benefi[- cost ratio of .3:1.0. Alternative ~2: A proposed dike begins near Highway 159 passes below Salzar Reservoir, crosses Rito Seco Creek channel, a county road, High- way 152, Peoples Ditch, and outlets into Culebra Creek south of San Luis. The dike would be approximately 2.7 miles long. The first 0.85- mile would inundate an average width of 560 feet of land on natural ground under the maximum design storm condition at a depth including freeboard, of 7.6 feet against the dike. The last 1.8 miles would inun- date an average width of 1,280 feet on natural ground [58 acres] under the maximum design storm event at a depth, including freeboard of 4.8 feet. [See Figures 1, 2, and 3]. There would be two siphons under the dike. The first below Salazar Reservoir - a 100-ft. 36" diameter reinforced concrete siphon to carry approximately 25 cfs of irrigation water. The second would be For the Peoples Ditch - an 800-ft. 36" diameter reinforced concrete siphon [o carry approximately 25 cfs of irrigation water. Where the dike crosses the county road and Highway 152 reinfo n:ed con- crete box culverts and low water bridges would need to be constructed as do ramps over the dikes. The proposed dike is described as follows: Station 0+00 to 45+00: A 7.6 foot high dike with 5.6 feet: depth of flaw and 2 feet freeboard at a velocity of 2.17 fps; the c:apaci[y is 3400 cfs. The total volume of fill (dike and core trench) is 57,900 cu.yds. The water surface width in front of the dike will average 560 ft. Station 45+00 to 140+00: A dike with 2.8 ft. depth of flcw and 2 feet freeboard. At a velocity of 3.28 fps, the capacity is 6,700 cfs. The total volume of fill (dike and core trench) is E3,200 cu. yds. The water surface width in front of the dike will average 1,280 feet. There are 19 acres of dike area to be revegetated to native grasses. There are 338 acres of land area in front of the dike which is the flow area of the water.