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<br />- L9 - <br /> <br />- 20 - <br /> <br /> Table 3 <br /> PEAK DISCHARGES (cfs) <br /> 10 25 m SPF <br />Out of Tarn '" 800 900 1200 <br />Below Lehman Gulch 500 800 000 1300 <br />Below Illinois Gulch 500 800 000 1400 <br />Belm.. Sawmill Gulch 550 800 900 1400 <br />Below French Gulch 700 850 1200 1900 <br />Below North Barton Gulch 750 850 1200 1950 <br />Below Swan River 1050 1150 1250 2400 <br />HAZARDS OF LARGE FLOODS <br /> <br />FLOODED AREAS A~D FLOOD Dk~GES <br /> <br />The amount and extent of damage caused by any flood <br />depends on the topography of the area flooded, depth and <br />duration of flooding, velocity of flow, and developments in <br />the flood plain. The occurrence of an Intermediate Regional <br />or Standard project Flood on streams in the study area at <br />the present time would result in inundation of land adjacent <br />to the river, damage to residences, roads, streets, bridges <br />and culverts, public utilities, and interruption of traffcc. <br />flood waters flowing at high veloci ty and carrying floating <br />debris create conditions haz,1rdous to persons and vehicles <br />attempting to cross flood'Od areas. High velocity flows <br />through Breckenridge can erode stream banks thereby threaten- <br />ing the found~tions of buildings and bridge abutments and <br />creating hazard to curious spectators and occupants of struc- <br />tures. Col<l night" c\uring thpearly part of the runoff season <br />cause c;trcets subject to shallo,,-' flooding to become glazed <br />ice. Sewage, garbage and other organic materials carried or <br />deposited by flood waters create hazards to health. Serious <br />problems could result in providing emergency medical, fire <br />and law enforcement services to areas isolated by floods. <br /> <br />The areas along the Blue River through the town of <br />Breckenridge that would be inundated by the Intermediate <br />Regional and Standard Project Floods are shown on Plates 4 <br />through 10. Plate 3 is an index map showing the relative <br />location of the plates within the town of Breckenridge. <br /> <br />During floods, debris collecting on bridges or culverts <br />decreases the flow carrying capacity and causes greater <br />water depths upstream of the structures than would have <br />occurred without them. The maps and illustrations reflect <br />consideration of the channel as it exists today and show <br />the baCkwater effects with the crossings assumed completely <br />plugged with debris. With few exceptions the primary cause <br />of flooding outside of the banks is caused by debris <br />accumulation plugging the crossing structure. Between the <br />Village Road and Lincoln ^ve. crossings flood flows leave the <br />banks on the east side of the channel due to inadequate <br />Channel capacity. In addition to the crossing structures, <br />the Four Seasons Pond dam also causes localized flooding. <br />Due to the steepness of the channels in the upper or southern <br />portion of the reach, flood flows would normally be contained <br />within the channel banks with the exception of these <br />obstructions. <br /> <br />At the Four Seasons Pond both the Intermediate Regional <br />and Standard Project Flnods are forced out of the banks of <br />the channel and localized flooding occurs. Flood waters of <br />both events, however, ure generally contained in the area <br />west of Highway 9. <br /> <br />Between the Village Road and Lincoln AVe. crossings the <br />channel of the Blue River on the cast side is oat adequate <br />Lu pd3S either the Intermediat~ Regional or Standard Project <br />Floods. The water will leave the b':1fik. near the existing <br />ped,:,gtri<.ln bridge crossing between these two t-oacts. Once <br /> <br />C\) <br /> <br />l,,""d RK/CO'.;.I'I....'Ii'"'r["'J"""'~"'" <br /> <br />------ ---~-- <br /> <br />C\J <br /> <br />.Nm'dR.:tli"'i:..'.(]~"I"lnq,nuc's,h1t;. <br /> <br />------------~------- <br />