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<br />Works of Improvement <br /> <br />The low stage of ,the principal spillway is set at the'elevation of the <br />50-year sediment volume'with the top of the low stage set at the level <br />of the 37-1/2 year frequency storm runoff volume. A drawdown't'ube' is' <br />planned to drain sediment pools so there will be no permanent pool as <br />required by the Colorado State Engineer. The crest of the emergency <br />spillways are set at the 50-year frequency storm runoffvblume: To ':, <br />confine the low stage spillway releases to the capacity of each floodway, <br />design requires that the maximum' low" stage discharge for each' structure <br />will be the greater of 15 c.f.s. or the discharge' required to release, <br />the 37-1/2 year storm runoff storage in 10 days or less. <br /> <br />Emergency Spillway <br /> <br />The emergency spillways will be vegetated earth.' They will be excavated <br />into the claystone and siltstone bedrock or firm alluvial clay. The" <br />frequency of flow in the spillways is once in 50 years. In order to <br />preserve the natural vegetation in' the return areas, no ei<it channel <br />shaping has been considered. <br /> <br />Fencing and Seeding <br /> <br />The dams, 'emergency spillways, borrow areas, and other"areas disturbed <br />during construction will be vege~ated for erosion control,and fenced to <br />preclude grazing and access to"roving ,I ivestock and to' human foot and <br />vehicular traffic.' However, in 'seasons with, good production hay harvest- <br />ing will be permitted. SpecificCltions for 'fencing will meet those of <br />the Service and the Colorado Division of Wildlife. Empty borrow areas <br />will be graded for total drainage before seeding. Where Clvailable, <br />suitable topsoil will be stripped from the site and stockpiled for later <br />seedbed preparation. Earthen areas of the spillways will be compacted <br />to a firm seedbed. Areas to be seeded also will be fertil i,z,ed, When <br />weeds compete with the vegetative cover, they shall be mowed early in <br />the summer. The areas are to be protected from buriling,. ,..,' <br /> <br />land Rights and land Use <br /> <br />Approximately 802 acres are required for the '10 ,floodwater retard'ing' <br />structure sites. ' This includes the total area needed ,for the--lO,'sites - <br />with emergency spillway, flood pool, and emergency'spillway return,' <br />Eighty-two of these acres will be acquired forthe,dam and emergency <br />spillway areas compr,ising 67 acreS of pasture, and r-angeland,'and'15 <br />acres of nonirrigated cropland._ The remaining 720 acres are,required <br />for the pool areas and emergency.,spi llway returns. Of this 720-acre <br />area, 715 acres are pasture and"rangeland'and 5 acres'are"rionirrigated <br />cropland. All the land required is in private ownership except sites <br /> <br />38 <br />