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dpdrtrnent ; n the downstre~'" re<lch 01 Toll GaTe Creek WilS flooded. The <lvcrage flood width In tho lowor roaches 01 the creek wdS reported to ~e about I,OuQ feeT. IIgricul tural areas, res;,IOnCf1S end ut; I ;ties suffered extensive aa~ges. Am.:Ijor storm On ill and 17JuM 1965cxfcndod over the entire Toll Gate Creok basin with rainfall amounts of from two to four inches. An estlrr..ated poak Gi sch<:lrge of 16,000 cuo Ic feet per second ~t Sixth Av""".. un Toll Gate Creek wdS tho groatost of record on tne stream. Dam<)gc~ tota ling ~6(j~.OOO resu I ted in tl'o TOil ,,,,to Creek basi n. Nearly every bridgo across Toli Gate Creek was dam<lged ordllstroye<J. FigureS illustrates tne flood damage at One bridge crosslJlg due to the 1965 flood. Flood Control Structures Thero ;sre no e~lst In9 flood control structures on Toll Gate Cre"k. nl' city of Aurora has a pllln re~u Ir i"~ channelizat Ion ot Toll Gate Creek and its rMjortribuhrles prior to flood plain development. The channe I ~ork wou Id consist of wide, sha Ilow sloi""'d. gr"ss~11 ned channels with drop StructuMs to control velocities wlthtn tM channel, desIgned to contain the IOO-year flood with veloctties not to exceed 8 leet per sox:ond. The al ignment and bed elevations of t~" pi anr.ed channelworkareshownontheflOOdedaream"psandprofiiestnthls report. All design work on the proposed channelS was done by the city of Aurora and their engineering consultants. Potontial Floods Two potential flOOds, the Intermediate Regional and Standard Proj..ctFloods.weredeveloped Inordertoanalyzethefloodhalard in the study re3Ch. The Intermediate Regional Flood has a probability of occurrence of OnCe In 100 years On the aver~e and is generally accepted by the publlc as II minimum I imlt for use In applying flood plain rOgu- lations. ThelntennediateRegional Flood for the Toll Gate Creek hasin was developed by an analysis of gaged streams in the Oenver region, with runoff factors adjusted to reflect projected future urbani<:<ltlon. The computed peak discharges for the Intermediate Reglondl Flood at several points On the streams In the study reilch are shown in taole 2. TM Standard Project Flood ;; defined " theCloss<lry 'M Nipres"ntsa practical upper limit of flooding. Peak discharges ." ", Standard Project Flood or sever,,1 points " the Tall ('~lte Cr<>ek F Iqure~. Flood ot 16 Juno 1%5 OJl TOil U3te Creek badly da;i\<lncd this rai I road cr05sIrrq at the 'I'IOuth of tnostrea<T\. basin are alSO Shown fn tilble 2. floods even larger than the Standard Project Flood are DOSS Ible, ~ut the probatlll i1y of larQer floods is e~tremely remote. " "