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sho,m In T~bte 3. Synthesized st~ge hydrographs of the Intermediate Reglon~1 Flood ~t selected loc~tlons along the stre~ms under study ~re shown on PI~te 3. FUTUREFLOOOS STANOARO PROJECT FlOOO Although floods of the s~me ~gnltude ~s those th~t have occurred In the past could recur In the future, and larger floods ~re possible, discussion of future floods In this report Is Ilml"ted "to "those deslg- na"ted as "the 'ntermedl~te Region~1 ~nd S"t~nd~rd Project Floods. The S"t~ndard Proj&ct Flood would be l~rger ~nd would occur less frequen"tly "then the tntermedl~te Reglon~1 Flood. A St~nderd Projec"t Flood would be a rare event, but could reasonably be expected "to occur In the future. St~ndard Project FlOOd runoff Is that generated by the most severe combination of me"teorologlcal condItions reasonably ch~racterlstlc of the hydrologic region, excluding extremely rare comblnlltlons. Pellk flows for the Stand~rd Project Flood were developed In "the same mllnner as described for the Intermedl~te Reglonlll Flood. Pe~k flows for a Stendllrd Project Flood at selected locations on the streams ~re ~lso Shown In T~ble 3. During floods, debriS collectIng On bridges could decre~se their flow c~rrylng capacity and cause greater w~ter depths (b~ckw~ter effect) upstre~m of those structures. Since the occurrence and ~mount of debriS are lndetermln~te fec"tors, only "the physical ch~r~cterlstlcs of the structures were consIdered In preparing the maps ~nd other Illustr~- tlons showIng the Intermedia"te RegIonal and St~nd~rd Projec"t Floods. These maps ~nd il IU5tratlons reflect conslder~flon of veget~tion nonmal Iy exIsting In floodw~ys, ~nd show the backwater effect of obstructive bridges. but do not reflect Incre~sed water surface elevations "that could be caused by debrIs collecting ~galnst bridges, or by deposition of sIlt In the s"tre~m channel. TABLE 3 PEAK FLOWS FOR INTERMEDIATE REGIONAL AND STANDARD PROJECT flOODS Location Intennedl~te Reolonal Flood c.f.s. S"tandard ProiectFlood c.f.s. INTERMEDIATE REGIONAL FLOOD RoarIng Fork River ups"treamllmltofstudy RoarIng Fork River below Hunter Creek Roaring Fork River below C~stle Creek Hunter Creek Castle Creek 3,300 4,400 4,600 6,200 5.700 1,700 1,300 7,600 2,500 1,900 The Intermedlnte Regional Flood Is one that could occu~ ~bout once In 100 ye~rs on the ave~age, although It may occur In ;:,ny yMr. This flood was determined by the use of flow-frequency curves derived from st~eam- flow records. ConsideratIon was given to cllm~"tlc conditions as They ralate to snowmelt, and to the runoff characteristics of the basin. The pellk flows derived for The InTermedl~te Reglon~1 FlOOd ~"t vnrlous locatIons on the Roa~lng Fork River ~nd Cas"tle and Hun"ter C~eeks are FREQUENCY flow-frequency Cu~veS werA developed from streamflow records obt~lned at thegClglngshtlons listed In TClble 2. The June 1917 flOOd. the largest of record on the Roaring Fo~k Rivar ~"t Aspen, had a f~equency of occu~rence of about once In 70 yea~s. As prevIously indicated, an InTermediate Regional flood Is one th~"t could occu~ about once In " "