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<br />Purpose "od Seup"
<br />
<br />This renArt was p",are~ ~~ c"ldn '~"'. "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. Ndcional 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"ur"",su(Data al-,d Records
<br />
<br />Informat.ion 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()grdplllc mapping having a contour interval of 2
<br />
<br />feet and a scale of 1:240~ ",ere 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 ",ere 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 La", 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 \<later runoff occurrin'J from a 1'3~-year storm.
<br />
<br />The "rea studied was a tri3ngle between Greeley, Port Collins, and
<br />
<br />Loveland. Since the wat,,," surfilce profile In the present study Is more
<br />
<br />detd iied and r",fl"ct" Cui t "lit. cond i tio"" ill l~iS, i l "up",,;,,..:;,,,; Lb"
<br />
<br />Larlmer-;.,'eld Drainage Study.
<br />
<br />^ drain,,'lc Gtudy of the C::>nsolid<lted Law Ditch prepared in
<br />November L978 for the Eastman Kodak Company by Leon<lrd Rice Consulting
<br />
<br />Water Engineers, Inc. sho..." higher discharges for Tbe Slough thiln the
<br />
<br />corps data. More accurate lntormatlon and a more detililed 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 />l>\o<1el (S'",'MM) rather than th" Color"do vrb3rl Ilydrogrdph Procedure.
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