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<br />Purpose "od Seup"
<br />
<br />This renArt was p",are~ ~~ c"ld" '."'~ "1.' . 1
<br />..-~ - ~~ 7U ~ v~. 0.. CliHS In p "nning the
<br />use and re'.lulatianof floodplain areas such that flood hazards and
<br />
<br />future damane~ '" "" 1 d
<br />" ~ .,,',,'It: ze .
<br />
<br />It includes information on historical
<br />
<br />floods, existing factors whiCh Influence the flood hazard, and the
<br />nature and extent of probable future flood~.
<br />
<br />The report dilta
<br />
<br />incllldes a flooded d 11
<br />area map e neating the
<br />
<br />1~0-year flood boundary, flood profiles, and floodplain cross sections
<br />showing the high water elevations for the lll-, 50-, 100-, and 5110_year
<br />floods at selected reference ""Ints, A 1
<br />,,- supp ement to this report in
<br />
<br />Ch,
<br />
<br />form
<br />
<br />of a Technical Addendum includes the supporting engineering
<br />
<br />and hydrologic dat~ which may also be used in the location and
<br />of roads, bridges, and Channel modifications.
<br />
<br />design
<br />
<br />Acknowledgements
<br />
<br />The below listed Ol"encies, '1 'M'" ~. d.
<br />~ "'~, 0 rganiza..lons, an pr lvate
<br />
<br />citizens supplied inforMation and data.
<br />
<br />Their
<br />
<br />assistance
<br />
<br />,od
<br />
<br />cooperation are appreciated and gratefully acknowledged.
<br />u. 3. National Oceanic and Atmospheric Administration (NOAA)
<br />U. S. Department of the Interior, Geological Survey
<br />U. S. Department of the Army, Corps of Engineers
<br />Colorado Water Conservation Board
<br />Color~do State Highway Department
<br />Weld County Department of Planning
<br />The Town of Severance, Colorado
<br />Mr. Richard Tallman
<br />
<br />Aerial photography and contour map[.linq Were provid"d My W"l<J
<br />County and the Colurddu Water Conservation &lard through a contract
<br />with Benchmark Mapping Services of Denver, Colorado.
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<br />S"urc",so(Data al-,d Records
<br />
<br />Information on pll.~t floods waS obtained from interviews \<1\ th
<br />
<br />resld"ntsof the Severance area and through ne\<lspaper articles. cross
<br />
<br />section data and t<;>p()graplllc mapping having a contour interval of 2
<br />
<br />feet and a scale of 1:240~ \<Iere established by photogrammetric methods
<br />
<br />from flights made on April 11, 1978. These data were supplied by the
<br />
<br />Colorado Water Conservation Board and weld County.
<br />
<br />U. S. Geological
<br />
<br />Survey 7.5-minute quadrangle maps with 1~-foot contour intervals at a
<br />
<br />scale of 1:24,0@0 \<Iere also used in the study.
<br />
<br />Bridge data were
<br />
<br />supplied by the Corps of Engineers. Topographic mapping of a portion
<br />
<br />of John Law Reservoir \<Ias supplied by Severance. This mapping has a
<br />
<br />contour interval of one foot and a scale of 1:600.
<br />
<br />Relat"d Plood Studies
<br />
<br />The Larimer-Weld Regional Drainage Study, completed in 1973,
<br />
<br />det'anlined pe3k storm water runoff occurring from a 1'3~-year storm.
<br />
<br />The "rea studied was a triangle bet\<leen Greeley, Port Collins, and
<br />
<br />Loveland. Since the wat,,," surfilce profile In the present study Is more
<br />
<br />deta iied clnd r"flcct:; Cui t "lit. cond i ti,.H''; ill l~iS, i l :;up",,;,,":;,,,, Lbc
<br />
<br />Larlmer-.oeld Drainage Study.
<br />
<br />^ drain,,'lc Gtudy of the C::>nsolid<lted Law Ditch prepared in
<br />November L978 for the Eastman Kod<lk Company by Leonard Rice Consulting
<br />
<br />Water Engineers, Inc. sho\<l" higher discharges for Tbe Slough thiln the
<br />
<br />corps data. More accurate lntormatlon and a more detailed proceaure
<br />
<br />have allowed for the reduction in discharge. The Corps had 1980 soil
<br />
<br />survey information available and used the EPA's Storm Water Management
<br />
<br />"lodel (S'",'MM) rather th<ln th" Color"do vrbilrl Ilydrogrdph Procedure.
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