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flows along Spring Creek. However, the Rossborough, woodwest, and stonehenge ponds have relatively large tributary areas and may have a significant effect on flows in Spring Creek. Therefore, these three ponds were included in the SWMM analysis. Discharges tram the Woodwest pond are routed through the CSU Veterinary Hospital pond prior to discharging to Spring Creek; therefore, the CSU pond was also included in the analysis. Channel Characteristics On-Stre4~Q~t~otion The Spring Creek Channel is tributary to the Cache La POlldr.. River immediately east of Fort COllins. The Spring Creek Channel is generally deep and well-defined with a relatively wide, gentle overbank area throughout much of its length. The majority of the Channel has been maintained as a draina,geway, although several constrictions exist at roa,dway and railroad crossings. The most severe of these constrictions is through a short reach between College Avenue and the Burlington Northern Railroad. lIere the Channel has been replaced with a storm sewer which carries base and minor storm runoff under the Johnson Mobile Home park and several commercial developments. Other than Horsetooth Reservoir, Dixon Reservoir is the only major reservoir within the Spring creek Basin. Dixon Reservoir is located on the western edge of the basin imm"diately belOW the hogback which impounds Horsetooth Reservoir. Dixon Reservoir intercepts and stores runoff from al'Pt'oximately 250 acres of drainage area, making this area essentially non-contributing to the Spring Creek channel. soille Although not specifically constructed for flood control. several other man-made embankments crOSSIng the Spring Creek channel effectively store runoff and attenuate flood peilks during flood eventle. The Gingery study identified embankments with potential for inadvertent detention and included them in the analysis. The embankments which were included in the Gingery study inCluded the Taft Hill roadway embankment, the Burlington Northern Ra,ilroad embankment west of College Avenue, the Colorado &- Southern Railroad embankment west of Timberline Road, and the Timberl ine The Spring Creek sasin has soils typical of the Nunn-fort Collins-Ulm and Table Mountain-Paoli-Caruso associations. The Nunn-Fort Collins-Ulm association predominates in the w~stern portions of the Spring Creek Basin, while the Table Mountain- Paoli-Caruso association is located in the eastern portion of the basin. Soils in the fluvaquents-Flu'vents associatiun are found primarily along the Spring creek Channel itself. Sui Is of the Nunn-Fort Collins-VIm and Table Mountain-Paoli-Caruso associations have moderate infiltration rates, while tile soils ot the Fluvaquents-Fluvents association have moderate to low intiltration rates. Road embankment. 'I'his study removed the modeled inCldvertent Road due to the 1987 construction of a '-' Data Acquisition detention at Tl.mh",rline bridge at Spring Creek with ~ capacity 01 approximately ~OOO cts. Detention at the Burlington Northern Railroad was modifil1d to "imulate a dam brei'lch for the lOO-yeilr ""rJ ",Oo-y",ar events, as discussed in Section 4.4, because the Chen ,,-nal ysis 01 the embankment showed it to be U!lstabl" during these events. '" Review of Previous Studies The Gingery report ilnd technical addendum wert' reviewE'd for pllrposes of identifying all results, dssumptions, ,1nd !-'rocedures used in the previous hydrologic a,nalyzis. Di"cussions were held with city Staff In order tu identif:r' ilOprovement" CO'Hotruct.ed "