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become trapped oc 1501at6~ in :;>verbank Jceas reSJ iti ng ir f loo.di nJ deD~hs greater than t~QSe shown on tne flood profi las. Flood; ng i::; a iso i ndi cated in three "ceaS prQ~6cted by s"la! I light Iy sodded san~ a1a gra.~e I Ie-vees. The Irei I levees at these locatlo1s are not <}x- pect<}d to '~Ithstar.c the erosi ve lorce Of a major f lood, a~d will a I".,ost cerrai n Iy fai I, I loo~i ng ar.edS beyond. From the confluence with rJbnument Creek to Acadumy Bouleva~d, Cottonwood is contained In the deep channel, wIth al rosidential anl"S well abovOi the fl=d elevlltlor.::;. At Academy Road, however, the insuHlc1ent structure C1;Ipaclty wi II causa appro~lmately 1,125 cubic feet per secondot Intermediate Reglon<ll i1nd 2,560 cubic feet per second of the Standard Project floodflow to overtop the boulevard and flow westerly down Brookwood Drive 1Ind Imperial Drlve toth.. dralnaae"ay west of Price DrIve where itwlll be Intercepted and rei"urned to Cottonwood Creek. In this area, many residential properties wi II be flooded by both major floods. Along Academy 6oulevard,thewaterovertoppingtheroad>l1ly,,111 flood several coo- merclal propertIes and upstrollm of the Boulevard many residential propertlesonbothbanksotthastreamwlllexperlencetlooding. Menyresldentlal properttes 00 the north side near Station 95-+00 will be inundated froo th.. expected failure of the gravel and sand levee. The failure of another lev<}e near StatJon 121+50 wIll resultlna diversion of 85D cubic feet per second of the Intermediate Regional Flood a~d 2,!50 CUDlc teet per second ot the Standard Project flood waters down Boysenberry Drive to Brookwood Drive and down Brookwood to return to the crock near Station 95+00. The rernalnderof Cottollwood Creek floods agricultural land, but It Is eKtnl_ly importa~t that future development of the valley doeS not Include th" areas that wi II bc Inundatud. From Station 115+00 to Station 221+BD the creek floods wlde areas of , pasture and range land, but does not endanger any Improved properties. Atove Statio~ 221+80, 1""e creek is again contained I n a d.."p Iy eroded channel and wi I i rr"'~..nt no haz<lrd to any res I denti a I proper1"ies. The north Tributary to CoTtonwood Creek Is eroded Into a deep ch::lnnel. The area Is currently rangc land and the deep nllrrow valley Is unsuitable for development. FloodlngshOuldnaverbs1l problem in the upper reaches of the Cottonwood and north tributary, if development is not permitted in the narrow valleyS, and the stream crossing structures are adequately sized. The south tributary to Cottonwood Creek traverses a heav. ily developed residential area along Dublin Boulevard below Academy Boulevard. In this reach of the trlblJtary the stream flows in the median 01 the divided Dublin Boulevard. As can be observod from the flooced area maps, rnany residentlai properties will be flooded along Dublin. At the Intersection of Dublin and Wlcklow Circle the trlbu- tarylSSharplydlvertedfromifswesterlycoursenortherly into Cottonwood Creek. This diversion Is made within a double 42 inch pipe culvert u1der the west bOund lanes of Dublin. The culvert under Dub I In Is not large enp~gr to accept a II the diSCharge trom either major fiocd, therefore, 777 cu~lc feet pcr second of tre Intecnedlste Regional Flood a~d 1,473 cu~ic 'Silt per second fro," the Standard "'ro- j8Ct Flooc i, c~crlec ,,,'est ~lon9 D.w i I r oou Iilv~rd. The F lood~ater5 wi II contim.e we5t.'~rd 310ng D.Jbl in Boulev"rd, 200 leet p'Jst Y\t6.1ne ''',ay, ,^.hort) It 'di I I .un '.'ith s~eet t'/?8 Ilow ;r ~ so~th.,rl!, direct;on into a s",~11 tr;but::lry of f10nument Cnwf'.. Thelnrcrnediatefleglonal Flood will bocontalned In tre double 9' X 9' CJlvect undur Acade~y Boulevard, but St~ndard Project FIGod wi II overtop the roadway. TIle remaInder of the south tribut"cv fro", Academy Boulevard east Is currently undevelopoc, ox- c;~p t for a tenn I s cl ub neM Stati 011 85+QO w.11 c~ .,,' II I ~~vc I ts cuts I de tennis courts f loodec, but no ddm.age ~hou Id be incurred to the bui Id- ings. Velocities, RaTeS of Ri5e, and Duration Table 3 Includils the flood cnaracterlstics along ,~tto~wooJ Cree~ a~d Its trlbu~aries. The J~tu or Table 3 ;ndi- cates ~Y8r~gec ~xlmy~ concltioc~ with heights 01 r;5C. rate, of 17 "