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<br />scour and sediment and debris deposition. inct e tangible and
<br />intangible losses. Tangible damages subjeqt Ilea' :1 quantification
<br />include physical damage to land and improv~ment; ~!i:'oPsl emergency costs,
<br />and loss of business and other income, bot~ in ' ~1~4ra . nt to flooded
<br />areas. Intangible losses are not su~cept~~le t " :,n,',',~~",,* ~,evaluation
<br />and include danger to human life, h~an dl~com ,. :~n~W and exposure
<br />during floods, creation of condition~,!,' detriiment, ~,'~' ,,:0, I,".e..,',~th and secu, rity,
<br />and interruption of normal communi ty . 'acti vilties. " rhysiC~l damages in-
<br />clude cost of cleanup, damages to bui1ding~ and c rtents, and damage to
<br />other improvements and property. . ! ,;
<br />Ii! .
<br />77. The Barrie~ Dam-Pueblo Floo~way ~roject!provides a high degree
<br />of flOOd, protection, for the major PO~',tion d1f' the,'~",i"ty, ,O,f,', Pueblo; however,
<br />an appurtenant feature of this impro'(ement, the 11.yee on. the left bank
<br />of Dry Creek above the Denver and Riol Grand1e West~tnraHroad bridg~,
<br />does not provide the same high degree of flpodprotection as the maIn
<br />.floodway. Barrie~ Dam} a flood' detention, s~ruct,ure 10, ca',ted at the
<br />Pueblo Damsite, WIll be replaced by Pueblo pam and Reservoir. The
<br />Pueblo Floodway together with regulation prpvided'by Pueblo Reservoir
<br />will protect the city of Pueblo against flopds in excess of standard
<br />project flood magnitude. There are a,ls,o se~\reral, ,~""m ',P, or: tan,t developments
<br />in the flood plain near the city which at p esent:have some flood pro-
<br />tection but not to the degree provided by t e main floodway levees;
<br />namely, the two water works at the western dge ,of Pueblo upstream
<br />from the floodway and the sewage treatment lant at-'the eastern edge
<br />of the city below the floodway. I, " " .
<br />
<br />78. Downstream from Pueblo, the Arkan~as River flows through a
<br />broad valley highly developed for agricul tutal purposes. Several fac-
<br />tors contribute to complex problems in the yalley between Pueblo and
<br />John Martin Reservoir. The normal str, eamfliw is, ,diV" er,te,', d and re, diverted
<br />for irrigation uses. Long reaches of the rver are. often dry, or nearly
<br />so, and irrigation canals parallel to the rver frequently carry more
<br />water than flows through the river channel. ' Tributary streams con~
<br />tribute little to the perennial flow of the~river,but frequently flood,
<br />and carry large quantities of sediment into the main stem. Flows
<br />remaining in the main stem after diversion or irrigation are not
<br />adequate to maintain a channel through sedi~ent deposits. The result
<br />is an acceleration of aggradation which red'cesthe channel capacity,
<br />causes channel changes, and creates obstruc ion to flow. Consequently,
<br />flooding becomes more frequent and severe w'th increasing adverse ef-
<br />fects on agrictilturaland other development throughout the reach.
<br />Irrigation interests have indicated that th river channel aggraded
<br />four to six feet in one ten-year period;' T maintain their diversions
<br />in operating condition, it has been necessa to raise the crests of
<br />diversion'dams every few years. The aggrad~tionbelow the diversion
<br />diminishes the ,effective head available for bypassing sediment and ' ,
<br />debris through the structure before it ente~s the,canals and ' thereby, "
<br />increases the cost of maintenance of the ir~igationsystems. Aggradation
<br />also contributes to drainage problems because the higher streambed levels
<br />cause higher ground wa~er tables.
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