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<br />Figure 15. Strea~ C. At Taft Hill Road looking southwest,
<br />~ - -'--- .~~^
<br />v.....,,""~ M''"
<br />
<br />However, scattered urbanization 1s occurrlng in the vicinity of U.S.
<br />Hlghway287.
<br />
<br />The study reach of Fossil Creek extends from its confluence with
<br />th~ Cache 1& Poudr.. River upstreaOl to Taft Hill Road, .. dh~..m::.e of
<br />about 13 miles. Development on the flood plain within the reach is
<br />relatively sparse. The most COmmon form of development is that asso-
<br />ciated with far~steads and an agricultural area. However, because
<br />urbanization is occurring near U.S. Highway 287, studies were conducted
<br />on several Fossil Creek tributaries in,this area. These are su~rized
<br />below,
<br />
<br />. (Stream A). A major right-bank tributsry of Fossil Creek enter-
<br />ing just upstrea~ from the Colorado and Southern railroad. The atudy
<br />reacne:ltendSsDOut::'\;;m.ilesfromtbellloutbtoTllitHillRoa<i.
<br />
<br />.
<br />
<br />"
<br />
<br />.
<br />
<br />(Stream B). A left-bank tributary of the above~mentioned tribu-
<br />tary. The study reach extends from the mouth east of Shields Street to
<br />about 1 mile upstream.
<br />
<br />. (Stream C). A left-bank tributary of Fossil Creek, Which enters
<br />near Shields Street. The atudy reach extends about l~ milea from its
<br />mouth to Taft Hill Road.
<br />
<br />flOOD PROBLEMS
<br />
<br />Significant flood history is not available for Fossil Creek as the
<br />baain has been sparaely developed. It is known that overflow from
<br />creeks created a flood threat aouth of Fort Collina on Z5 July 1977.
<br />Flood experience in the area indicates that snowmelt flooding is
<br />uncom~n and that au~er cloudburata would be the most likely source of
<br />flooding. There are no sizable structures within the basin that were
<br />constructed specifically for flood control. Incidental flood control is
<br />provided, however, by some structUres. The largeat reservoir in the
<br />basin, Fossil Creek Reservoir, is used for irrigation. However, it
<br />provides considerable flood control effecta down8tre~. The Union
<br />Pacific Railroad crossing upstream frow Fossil Creek Reservoir acts as
<br />e do:unand reduces flooddischargea downstreaOl. Severaloff-strealll
<br />reaervoirs and one irrigation canal control runoff from a small part of
<br />the baain areS. The many road crossings alao reduce flood peak dis-
<br />chsrgea, aa discusaed in the hydrologic analysis.
<br />
<br />ALTERNATIVE LAND USE CONDITIONS
<br />
<br />.
<br />
<br />As the Fossil Creek basin is aubject to increasing urban develop-
<br />ment, the flood hszard was evaluated under future as well as exiating
<br />conditions. Changes in imperviousness that would result from land use
<br />changes w111 affect the runoff potential. To reflect the influence of
<br />changing development, three levels of urbanization vere considered.
<br />
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