Flood Insurance Study Morgan County, Utah, Unincorporated Areas
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1990
Flood Insurance Study Morgan County, Utah, Unincorporated Areas
Federal Emergency Management Agency
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Recommended Citation Federal Emergency Management Agency, "Flood Insurance Study Morgan County, Utah, Unincorporated Areas" (1990). All U.S. Government Documents (Utah Regional Depository). Paper 181. https://digitalcommons.usu.edu/govdocs/181
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COrmlunit i es participating in the National Flood Insurance Program "ave established repositories of flood haz.ard data for floodplain management and flood insurance purposes. This flood Insurance Study may not contain all data available within the repository. It is advisable to contact the community repository {or any addi tional data.
MORGAN COUNTY, UTAH UNINCORPORATED AREAS
, SEPTEMBER 2B. 1990
Federal Emergency Management Agency
COMMUNITY NUMBER 490092 TABLE O. CONTENTS TABLE OF CONTENTS (Cont'd) Page Page 1. 0 I NTRODUCTI ON •••••.•.•••••••••••••••••••••••••••••..•••••••••.••••
1.1 Purpose of Study ••••.•.•• •••• ••••••.•••• ••• ....• • ..••••••. • 1.2 Authority and Acknowledgments ..•.•••..•••••...... •• • ... • 1.3 Coordination •..•...... •.. Figure - Vicinity Hap...... 3 Figure - Ploodway SchematiL...... 14
2 0 AREA STUDI ED •••••••••••••••.••••.•.•••••••.•••••••.••••••••••.•••
2.1 Scope of Study ••.•••••••.•• •••• •••••• •• .••••• •••••••••• •••. 2.2 COlIIDunity Description ••.•.... •••• ..••••••..•. . . • ...•....• •• Table 1 - Principal Plood...... 5 2.3 Principal Plood Problem •••••••••••••••••••••••••.•.••.••••. 4 Table 2 - Suarnary of Dischargea ...... o...... 8 2.4 Flood Protection Heasures ...... •...... 6 Tobie 3 - Ro ughn ... Coefficient Range...... 9 Table 4 - Floodway Data...... 12
3.0 ENGINEERING HETHODS •••.••••••••.•••••••••••••••••••• . •••••• . • •• •.
3.1 Hydrologic Analy ...... Exhibit 1 - PLod Profiles 3.2 Hydraulic Allalyses ...... 0 •••••••••••••••••••••••••••••
Weber River Panels OlP-12P 4.0 FLOODPLAIN I1ANAGEHENT APPLICATIONS •••••••••••••••••••••.••••••••• 10 East Canyon Creek Panels 13P-19P Deep Creek Panels 20P-22P 4.1 Floodplain Boundaries ...•.••.•...... •...... 10 Cottonwood Creek Panels 23P-26P 4.2 Ploodways ••••••••••••••••••••••••••••• " .•••••..• ••••••••• . It Exh i bit 2 - Plood Insurance Rate Map ! ndex 5.0 1 NSURANCE APPLICATION...... 14 Flood Insurance Rate Hap
6.0 FLOOD INSURANCE RATE HAP...... •• . ••• •• •• •.••...• ••••••• .••• • 15 Exhibit J - Elevat ion Reference Harks
7.0 OTHER STUDIES ••• • ••••• • • • • •• •••••• •• ••••••••••••••• •••••• •• • ••••. 15
J .O LOCATION OF DATA...... 16
9.0 BIBLIOCRAPHY AND REFERENCES...... 16
ii PLOOD INSURANCE STUDY HORCAII COUNTY, UTAII (UNINCORPORATED AREAS) 2.0 APEA STUDIED
1.0 INTRODUCTION 2 . 1 Scope of Study
1.1 Purpose of Study Thi. Flood Insurance Study covers the unincorporated areas of Morgan County, Utah. The City of Horgan City has not been included in this This Flood Insurance Study investigates the existence and severity Flood Insurance Study. The area of study is shown on the Vic i ni ty of flood hazard, in the unincorporated are •• of Horgan County, Utah, Hap (Pigure 1). and aids in the administration oC the National Plood Insurance Act of 1968 and the Plood Disaster Protection Act of 1~73. This study The Weber River was studied by limited-detailed methods from a point hal developed flood risk data for various areas of the corrmunity near the conf luence of Co ttonwood Creek approximately 11.1 mi les that ",ill be used to establish actuarial flood insurance rates and upstream to the downstream corporate limit of Horgan City and from .53ist the connunity in its efforts to promote sound floodplain the upstream corporate limi t of Morgan City to a point approximately management. Minimum floodplain management requi rements for 2 . 9 m~les upstream, from Horgan City for a total length of participation in the National Flood Insurance Program (NFIP) are set appr~xlmately l4.0 mlle~. East Canyon Creek was studied by limited forth in the Code of Federal Regulations at 44 CFR, 60.3. detall~d methods fr.om its conf ~ uence with the Weber River upstream approxunately 5.1 mlles to a pOlnt upstream of Horgan City, and from In lome Itates or conrnunities, floodplain management criteria or the East Canyon Reservoir 2.2 miles upstream to a point near Big regulations may exist that are more restrictive or comprehensive Dutch Hollo,", f~r a tota.l . length o~ approximately 7.3 miles. Deep than the minimum Federal requirements. In such cases, the more Creek was studled by llmlted-detalled methods from its confluence restrictive criteria take precedence and the Stat e (or other with the Weber River to a point approximately 3.3 miles upstream. jurisdictional agency) will be able to explain them. Cottonwood Creek wa g studied by limited-detailed methods from its confluence with the Weber River to a point approximately 3.7 miles 1.2 Authority and Acknowledgments upstream.
The sources of authority for this Flood Insurance Study are the Portions of the Weber River (cross section N to cross section W) and National Flood Inlurance Act of 1968 and the Flood Disaster East Canyon Creek (cross section B to cross section U) were studied Protecti on Act of 1973. by detailed methods by Si mons, Li and Assoc i ates, Inc., for FEHA in February 1986, for the Flood Insurance Study for the City oC Morgan The hydrol.ogic and hydraulic analyses for this study were performed City (Reference 1). by the U.S. Geological Survey (USCS), Water Resources Di vision, Utah District (the study contractor), for the Federal Emergency The areas studied by limited-detailed methods were selected with Hanagement Agency (FEMA) , under Inter-Agency Agreement No. priority given to all known flood hazard areas and areas of EHW-85-E-1823. This ..ork ..as comp leted i n January 1989. projected development Or proposed construction through Harch 1992.
1. 3 Coordinat ion 2.2 Community Description
An initial Consultation and Coordination Officer's (CCO) meeting, Horgan County is located in north-central Utah in the mountains of attended by representatives of Horgan County, FEKA, and the study the Wasatch Range and is bounded on the north by Weber and Rich contractor, vas held on August 17, 1988, to identify the scope of Counties, on the east by Summit County, on the south by Sa l t Lake study and discuss the hydrologic analy,i,. County, and on the west by Davis County. The Ci ty of Horgan City is the county seat and is located approxima t ely 50 mi les north The re,ults of the study were reviewed at an intermediate CCO northeast of Salt Lake City and approximat ely 24 mi les southeast o f meeting attended by representatives of Morgan County, PEKA, and the Ogden. Accord i ~g to U.S . Census Bureau figures, the po pUl ation of study contractor on February 1, 1989. The study W81 acceptable to Morgan County Increased from 3,983 in 1970 to 4,917 in 1980 the County. (Reference 2) .
On December 6, 1989, the resultl of this study were reviewed at a final ceo meeting attended by representatives of Horgan County, PEKA, and the study contractor.
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APPROXIMATE SCALE ..... FE DERAL EMERGENCY MANAGEMENT AGENCY 16 o 16 32 4 8 MilES MORGAN COUNTY , UT 1 - ( - J - [UNINCORPORATED AREAS) VICINITY MAP :'i' ------The Weber River flows northwesterly through the study area. Its TABLE 1. PRINCIPAL FLOODS drainage area ranges from approximately 1,100 square mi Les above Horgan City to approximateLy 1,600 squar'e miles at the lower end of the study area. East ca,rn Creek, draining approximately 237 Peak Di scha rge. (cf.) square miles in the st)uthern part of the county, flows northwesterly to enter the Weber River just upstream of Mi 1 ton. l>eep Creek, with Weber River East Canyon Creek/Weber River a drainage area of approximatt..'v 20 square miles, flows generally rw: (at Dlvi 15 Slid~l {near HorBan~ {at Gatew!:l~ northward to enter the Weber River at Hilton. Cottonwood Creek 1890 flows west-southwesterly to enter the Weber River at Mountain Green (I) (I) 5,460 and has a drainage area of approximateLy 45 square miles. 1892 (I) (I) 5,760 Horgan County is a rural area of broad valleys bordered by 1893 mountains. The vaLLeys consist of cuLtivated and livestock-grazing (I) (I) 7,280 lands wi th severaL unincorporated convnuni ties and many res ident ia 1 1896 homes scattered throughout the area. Interstate Highway 84 and (I) (I) 7,980 State Highways 65 and 66 serve the residents of the area . The 1897 cLimate is characteristicalLy semi-arid continental. The mean (I) (I) 5,340 annual temperature is approximately 45°F, and the average annual 1907 precipitction is approximately 20 inches (Reference 3). 4,620 (I) (I)
2.3 PrincipaL FLood Problems 1909 6,600 (I) (I) 1912 The maximum floods of recot.. nave occurred during the Apri 1 through 3,910 (I) (I) June snowmelt period and have esulted in prolonged periods of high 1917 fLows varying from a few days to more than a month . Cloudburst type 4,120 (I) (I) fLoods and floods resulting from combined general rain storms and 1920 melting snow are also not uncolMlon. Principal fLoods of record at 6,000 (I) (I) USGS gaging stations 10133500, Weber River at Devils Slide; 1921 10134500, East Canyon Creek near Horgan (0.5 mile below East Canyon 3,810 ( 1) 5,500 Reservoir); and 10136500, Weber River at Gateway (2.2 miles west of 1922 Hountain Green) are shown in Table 1. 4,140 (I) 6,720 1923 Since 1896 on East Canyon Creek and 193! on the Weber River, 3,580 (I) 5,380 reservoir operation has been an increasingly important factor in 1936 reducing flood damage in the study area. However, Hood waters on 1,230 412 4,380 the Weber River and its tributaries still cause extensive damage to 1937 channels, roads, bridges, culverts, sewer and .... ater systems, and 2, ~OO 397 3,230 other public. and private property. Recently, r'eservoir operation 1952 hal\ reduced the flood damage below the reservoirs to a minimum, .... ith 4,810 872 7,600 the exception of the 1983 flood (Reference 4). The 1983 flood flows 1975 are not published at this time. but are estimated to be about the (I) 380 3,420 same or higher as compared to the 1952 flood (Reference 5). It was 1983 (I) estimated that the 1952 floodflows from the Weber Riv~r at Morgan 726 5,970 are approximately 6,000 cubic feet per second (cfs) and from East 1984 Canyon Creek at Horgan are approximately a SO-year event (Reference (I) 395 5,080 5). Hain flood problems that occurred due to the 1983 Hood were 1986 basement flooding, damage to sewer systems, and threats to the (I) 360 6,160 electric substations . Total estimatpd damage was $300,000 and $50,000 for privateLy owned dikes and volunteer time. (1) No record, gaging station not operated during these years. 2.4 Plood Prt'tection Me s sures 3.1 Hydrologic Analysis
Pour dams and reservoirs in the Weber River basin above Morgan City Hydrologic analyses were carried out to establish peak discharge provide significant regulat ion of flow on the Weber River and its frequency relationships for each flooding source studied in detail tributaries . Existing reservoirs include Rockport, on the Weber affecting the cOITIDunity. River (usable capacity of 60,860 acre-feet); Echo, on the Weber River (capacity of 73,940 acre-feet); Lost Creek, on Lost Creek Por streams that are regulated, the Weber River and E~ Jt Canyon (active capacity of 20,010 acre-feet); East Canyon Creek, on East Creek below East Canyon Creek Reservoir, the lOa-year discharges Canyon Creek (active capacity of 48,110 acre-feet) (Reference 6). vl!re determined uling magnitude and frequt:ncy analyses of streamflow records greater than SO years i n length and collected at gaging The U.S. Army Co r pl of Engineers (COE) studied the Brea station, 10133500, Weber River at Devil. Slide; 10134500, East approximately 20 years ago and was considering constructing dikes Canyon Creek near Horgan; and 10136500. Weber River at Cateway. through most of Horgan City along the Weber River (Reference 7). Also, streamflow records S years in length and collected at gaging These dikes were not constructed. stations l013SS00, East Canyon Creek below diversions near Morgan, and 10136000. Weber River near Horgan. provided information on the Temporary dikes have been constructed by private interests along the 1952 flood. The ecords were analyzed in a manner to reflect the Weber River during past floods. These temporary dikes have no effect of reservoir storage on high flows . The Weber River and East significant effects on the 100- and SaO-year floods. On Deep Cr~ek, Canyon Creek lOa-year discharges at Horgan City were coordinated a few hundred feet of dikes have been constructed below the brldge with those previously established for the Horgan City Flood on State Route S91. Insurance Study (References 1 and 6). According to the FEHA Flood I nsurance Study Cuidelines and Specifications for Study Contractors (Reference 8), if the previously established lOa-year discharge 3.0 ENGINEERING HETHODS plots within the 95- and 5-percent confidence limits (90-percent confidence interval) of the currently developed magnitude and For the flooding sources studied in detail in the cOrmlunity, standard frequency relation and lOa-year dischalle, then the previously hydrologic and hydraulic study methods were used to determine the flood established discharge is not significantly different statistically hazard data required for thi s study. Flood events of a magnitud~ which than the currently determined discharge, and it should be used. are expected to be equaled or exceeded once on the average duclng any Therefore, the lOa-year discharges determined by the methlJds used 10-, SO-, 100-, or 500-year period (recurrence interval) have been for the Horgan City Flood Insurance Study (References 1 and 6) were selected as having special significance for floodplain management and for used in this study. flood insurance rates. These events, corrrnonly termed the 10-, SO-, 100-, and SOD-year floods, have a lO-, 2-, 1-, and 0.2-percent chance, For the unregulated streams, East Canyon Creek above East Canyon respectively, of being equaled Or exceeded during any year. ~lthough the Creek Reservoir, Deep Creek. and Cottonwood Creek, the report recurrence interval represents the long term average perlod between "Methods for Estimating Peak Discharge and Flood Boundaries of floods of a specific magnitude, rare floods could occur at short Streams in Utah" was utilized to determine lOa-year discharges at intervals or even within the same year. The risk of experienclng a rare the desired ungaged sites on these streams (Reference 9). flood increases when periods greater than 1 year a re considered. For example, the risk of having a flood which equals or exceeds the lO,O-ye~r Peak discharge-drainage area relationships for the Weber River, East flood Cl-percent chance of annual exceedence) i n any SO-ye,ar penod . l S Canyon Creek, Deep Creek and Cottonwood Creek are shown on Table 2 . approximately 40 percent (4 in 10), and for any 90-yea r perlod, the rL~k of approximately 6':1 percent (6 in 10). The ana l yses reported hereln 3.2 Hydraulic Analysis reflect flooding potentials based on conditions existing in the ~ormlun~ty at the time of completion of this study. Haps and flood elevatlons wlll Analyses of the hydraulic characteristics of flooding from the be amended periodically to reflect future changes. sources studied were carried out to provide est imates of the elevations of floods of the selected recurrence intervals.
Cross sections for the backwater analysis of the Weber River, East Canyon Creek, Deep Creek, and Cottonwood Creek were field surveyed Table ~ Summary of Discharges
Dra i nage Area Peak Discharges (cfs) Floodinlt Source and Location (Square Miles) lO-Year 50-Year 100-Year 500-Year
Weber River Below Cottonwood Creek 1,600 1< 8,2001 1< - * 1 - Above Cottonwood Creek 1, 550 * 7,900 * Above East Canyon Creek 1,230 -* '" 6,3701 - At Morgan City 1,215 3,700 5,295'" 6,3701 10,205'"
East Canyon Creek At Confluence With Weber River 237 -:. 1< 1,4151 * At Morgan City 150 .IL O 1,095 1,415 1 2,545 Above East Canyon Reservoir 113 1: - 1< 1,100 - * Above Big Dutch Hollow 91.1 1: 1< 906 '" Deep Creek 2 00 At Confluence With Weber River 20 * 1: 580 - 1: At State Route 591 Bridge 20 - 1: -:. 678 * Above North Fork 11.9 * -* 403 '" Cottonwood Creek At Confluence With Weber River 45.1 * 1< 614 *
lPeak discharge regulated
2Ni nety-eight cfs is diverted fron. Deep Creek due to overtopping of the State Route 591 bridge.
*Not Determined above and below bridges, culverts, and diversion and drop structures. Road profiles were also field surveyed to compute the backwater effectl of these hydraulic structures. Additi onal valley Flood prof i les were drawn showing computed water-surface elevation. cross sections were surueyed between the structures to define for floodl of the .elected recurrence intervals (Exhibit 1). extremes in channel conveyance. Several crass sections were synlbelized from surveyed valley cross se ctions to improve tht1 The hydraulic analyses for t t i. Itudy were based on unobstructed def init ion of the water-surface elevat ion profiles. All hydraul ic flow. The flood elevation. shown on the profi les are thus structures were field surveyed to obtain elevation data and considered valid only if hydraulic structures remain unobstructed, structural geometry. operate properl:! , and do not rail.
Locations of selected cross sections used in the hydraulic analyses All elevations are referenced to the National Geodetic Vertical are shown on the Flood Profiles (exhibit 1). For stream segments Oatum of 1929 (NCVD). elevation reference lUrks used in this study for which • floodway was computed (Section 4 . 2), selected cross are shown on the mapl; the description of the marks are presented in section locations ar e also shown on the Flood Insurance Rate Hap Elevation Reference Harks (Exhibit 3). (Exhibit 2).
Roughness coefficients (Mann i ng's Itn") were chosen by engi neeri ng 4.0 FLOODPLAIN MANACI!MENT APPLICATION judgment and based on field observations of the streams and fLoodplain areas. The range of roughness coeffic i ents used in the The NFIP encourages state and local governments to adopt sound floodplain hydraulic computations are shown in Table 3. management programs. Therefore, each Plood Insurance Study provides 100- year flood elevat ions and del ineat ions of the ~OO- .lnd . S~O-ye~r floodplain boundaries and lOO-year floodway to aSllst corrwnunltles ln Table 3 - Roughness Coefficient Ranges developing floodplain management measures. 4.1 FLOOdplain Boundaries ~ ~ ~
Weber River 0.030 to 0.055 0.035 t.o 0.150 To provide a national standard without regional discrimination, the East Canyon Creek 0.030 to 0.075 0.040 to 0.060 I-percent annual chance (lOO-year) flood hal been adopted by PEHA as Deep Creek 0.040 to 0.050 0.050 to 0.070 the base flood for flOOdplain management purposes. The 0.2-percent Cottonwood Creek 0.032 to 0.050 annual chance (SOO-year) flood is employed to indicate additional areas of flood risk in the corrwnunity. For each stream studied in detail, the 100- and SOO-year floodplain boundaries have been Water-surface elevati ons Cor the 100-year flood on each stream delineated using the flood elevation. determined at each cro.s studied were computed by the Water Surface Profile (WSPRO) step section. Between crols sections, the boundaries were interpolated backwater computer program developed by the uses for the Federal using topographic maps at a scale of 1:2,400 (enlarged to a scale of Highway Administration (Reference 10). 1 : l,200), with a contour interval of 40 feet (Reference 14).
In s tream reaches of supercritical flow, t ht.: flood profiles were In the area of the City of Horgan City, floodplain boundaries were plotted at critical depth. The s t arting water-surface elevation for interpolated using topographic maps at a scale of 1:4,800, with a each step-backwater run made in an unobstructed channel was contour interval of 2 feet (Reference 15). determined by slope-conveyance method for subcritical flow and by critical-depth method for supercritical flo\l (Reference 11). At The 100- and SOO-year floodplain boundaries are shown on the Flood hydraulic structures, the methods of computing the starting water Insurance Rate Map (Exhibit 2). On this map, the 100-year surface elevations were flow-through-bridge contraction (Reference floodplain boundary corresponds to the boundary of the areas of 11), flow through culvert (Reference 12), and flow over road special flood hazards (Zones A and AE); and the SOO-year flOOdplain (Reference 13). The starting water-surface used for Cottonwood boundary corresponds to the boundary of areas of moderate flood Creek was the 100-year computed water-surface elevat ion of the Weber hazards. In cases where the 100- and SaO-year flOOdpla i n boundaries River at the confluence with Cottonwood Creek. are close together, only the 100-year floodplain boundary has been shown. Small areas within the flOOdplain boundaries may Lie above the flood elevations but cannot be shown due to limitat i ons of the map scale andlor lack of detai led topographic data .
10 For the streams studied by approximate methods, only the lOO-year floodplain boundary is shown on the Flood Insurance Rate Hap (Exhibit 2).
Approximate 100-year floodplain boundaries in some portions of the study area were taken directly from the Flood Hazard Boundary Hap (Reference 16).
4.2 Floodways
Encroachment on floodplains, such 41 structures and fi 11, reduces flood-carrying capacity, increases flood heights and velocities, and increase. flood hazards in areas beyond the encroachment itself. One a.pect of floodplain management involves balancing the economic gain from floodplain development against the resulting increase in flood hazard. For purposes of the NFIP, a floodway is used as a tool to a •• i.t local communities in this aspect of floodplain management. Under this concept, the area of the 100-year floodplain is divided into a floodway and a floodway fringe. The floodway is the channel of a stream, plus any adjacent floodplain areas, that must be kept free of encroachment so that the lOO-year flood can be carried wi thout substant i&1 increases in flood heights. Hinimum Federal standards limit such increases to 1.0 foot, provided that hazardous velocities are not produced. The standards that can be adopted directly or that can be used as a basis for additional floodway studies.
The floodways presented in this study were computed for certain stream segments on the basis of equal conveyance reduc t ion from each side of the flOOdplain. Floodway widths were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. The results of the floodway computations are tabulated at selected cross sections (Table 4). In cases where the floodway and lOO-year floodplain boundaries are either close together or collinear, only the floodway boundary has been shown.
Floodways were computed for port ions of the Weber Ri ver (between cross sections Nand W) and East Canyon Creek (between cross sections Band U) for the City of Morgan City Flood Insurance Study (Reference l). Those areas of floodway which extend into Horgan County have been included in this study. Several floodway widths on the Weber River and East Canyon Creek either extend into Horgan City or lie entirely within Horgan City (See Table 4).
The area between the floodway and lOO-year flOOdplain boundaries is termed the floodway fringe. The floodway fringe encompasses the portion of the flOOdplain that could be completely obstructed without increasing the water-surface elevation of the lOO-year flood more than 1.0 foot at any point. Typical relationships between the
11 BASE FLOOD FLOODING SOURCE FLOODWAY WATER SURFACE ELEVATION WIIHOUI Wtlt< \I (1.0-, MI A,. K.(",,~IO.h 'Nt IA\I WIUI,.. uc_ VIlOCIIY hOOOWAY ILOOOW"" C~O\\ \lelIO<. (>0\14"(' ' I I I M,,~IU IIUt,u, '''' II fll I \lCOI/O) (1IIItIGvOI East Canyon Creek
B _,470 493 1,055 1.3 5,030.0 5,030.0 5,031.0 1.0 C 9,925 388 630 2.2 5,033.5 5,033.5 5,034.2 0.7 0 10,955 426 688 2.1 5,036.3 5,036.3 5,036.9 0.6 E 11 ,805 ~340/5802 556 2.5 5,038.7 5,038.7 5,039.1 0.4 F 13,705 ~748/5282 859 1.6 5,040.6 5,040.6 5,041.6 1.0 C 15,055 1149/392 819 1.7 5,041.8 5,041.8 5,042.7 0.9 H 15,505 343/232 480 3.0 5,044.3 5,044.3 5,044.9 0.6 I 15,905 215/502 405 3.5 5,046.0 5,046.0 5,046.6 0.6 J 16,595 2003 523 2.7 5,047.4 5,047.4 5,048.1 0.7 K 17,205 2003 302 4.7 5,049.4 5,049.4 5,049.9 0.5 L 17,785 190/202 494 2.9 5,052.1 5,052.1 5,052.3 0.2 H 18,365 1883 475 3.0 5,053.2 5,053.2 5,053.5 0.3 N 19,085 46/112 207 6.8 5,055.7 5,055.7 5,056.0 0.3 0 19,105 46/262 218 6.5 5,056. 1 5,056.1 5,056.3 0.2 p 19,805 803 364 3.9 5,058.8 5,058.8 5,059.4 0.6 Q 20,145 75/102 378 3.7 5,059.4 5,059.4 5,060.1 0.7 R 20,765 88/282 380 3.7 5,060.9 5,060.9 5,061. 5 0.6 S 21,435 255 3 667 2.1 5,061.6 5,061.6 5,062.3 0.7 T 22,025 200 429 3.3 5,062.6 5,062.6 5,063.4 0.8 U 22,925 330 716 2.0 5,063.6 5,063.6 5,064.6 1.0
' Peet above confluence with Weber River. lWidth/Width within County limits. )Floodw~ y lies entirely within the City of Horgan City.
T FEDERAL EMERGENCY MANAGEMENT AGENCY A FLOODWAY DATA 8 L E MORGAN COUNTY, UT EAST CANYON CREEK 4 (UNINCORPORATED AREAS) BASE FLOOD FLOODING SOURCE FLOODWAY WATER SURFACE elEVATION
U(TIOh M[AA ..."HOui WI'" It[('UIA'OA'r ILOOOWA'r hOOOWAY ' NC 'A\I W ID1" A"'A VILO<"'r e"o', ,t r h()f4 O,U& /(1' (11111 I I I (\QUAIU (lUI "" III II \lCONOI (fill ,,(ivOI Weber River
N 56,360 213 1,382 4.6 5,030.5 5,030.5 5,031.5 1.0 0 57,060 288 1,318 4.8 5,031.8 5,031.8 5,032.5 0.7 p 58,110 285/202 1,217 5.2 5,033.9 5,033.9 5,034.5 0.6 Q 68,860 5643 1,567 4.1 5,074.8 5,074.8 5,075.4 0.6 R 70,160 875 1,830 3.5 5,077.4 5,077.4 5,078.4 1.0 S 70,555 67 459 13.9 5,079.6 5,079.6 5,079.6 0.0 T 70,565 67 449 14.2 5,082.5 5,082.5 5,082.5 0.0 U 70,700 311 1,192 5.3 5,082.5 5,082.5 5,082.5 0.0 V 71,240 237 1,320 4.8 5,082.7 5,082.7 5,082.9 0.2 W 72,620 180 741 8.6 5,085.6 5,085.6 5,086.6 1.0
1Peet above confluence of Co tonwood Creek. 2Width/Width within County limits. 3Floodway lies entirely within the City of Horgan City.
T FEDERAL EMERGENCY MANAGEMENT AGENCY A B FLOODWAY DATA L E MORGAN COUNTY, UT (UNINCORPORATED AREAS) WEBER RIVER Zone X
floodway and the floodway lringe and their signi t 1canee lU Zone X is the flood insurance rate zone that corresponds to areas floodplain development are shown in Pigure 2. outside the 500-year floodplain, area. within the 500-year floodplain, areas of lOO-year flooding where average depths are less than 1 foot, areas of 100-year flooding where the cant r i but ing drainage area is le •• than 1 square mile, and areas protected from 1.-1------tOO·V(A" 'LOOO I' .. AIN ------+itl the lOO-year flood by levees. No base flood elevation. or depth. are shown within thi. zone.
6.0 FLOOD INSURANCE RATE !lAP
The Flood Insurance Rate Hap i. designed for flood insurance and floodplain management applications.
For flood insurance application., the map designates flood insurance rate zones a. described in Section 5.0 and, in the lOO-year floodplains that were studied by detailed methods, shows selected whole-foot base flood eLevations or average depths. lnlurance agents use the zones and base flood elevations in conjunction with information on structures and their contents to ••• ign premium rates for flood insurance policies.
For floodplain management applications, the map shows by tints, screens, and symbols, the 100- and SO O-year floodplains, the floodways, and the locations of selected cross sections used in the hydraulic analyses and \..INIA' IS THI '''000 ILIVATION II"O .. IINC"OACHMINT LINI co I' THI HOOD ILIVATION .... ,TI" .NC .. O.CH ...... IT . floodway computat ions. • ,U"CH"""OII'HOTTOI.C,IO 1 0 .. OaT 1'1"'... IQUI"IMINTI 0" LISSI" .... MOUNT II' S .. e:CI"'IO IV STATI.
7 . 0 OTHER STUDIES
Figure 2. Floodway Schemat ic Weber River Hydrology. Davi 5 and Weber Count ies t Utah was prepared in 1979 by Gingery Associates, Inc. (Reference 17) . The flood frequency information in this report was considered to be the best analysis of flow ~.O INSURANCE APPLICATION on the Weber River since the last phase of reservoir regulation was completed in 1967 on Lost Creek Reservoir. The anal.ysis was based on a For flood insurance rating purposes, flood insurance zone designations frequency distribution for regulated flow from 1967 through 1977 and are assigned to a community based on the results of the engineering unregulated flow prior to 1930 at the Gateway and Plain City gages. analyses. These zones are as follows: The COE prepared a 1961 report, Design Memorandum No . 1, Weber River. Zone A Utah - Channel Improvement Horgan to Ogden which developed peak flows for the Weber River for the 10-, 50-, and l OO-year recurrence intervals at Zone A is the flood insurance rate zone that corresponds to the 100- Echo, Horgan, Cateway, and Plain City (Reference 7). The report does not year floodplains that are determined in the Flood Insurance Study by adequately reflect recent flow conditions and in particular, recent approximate methods. Because detailed hydraulic analyses are not reservoir operation, which regulates flow in the Weber River within the performed for such areas, no base flood elevations or depths are Horgan City study . sho\o1rl within this zone . The COE published a 1971 Report on Reservoir Regulation for Flood Zone A£ Control-Weber Basin Reservoirs (Reference 18). This report gives general design information, reservoir capaCltleS, spillway capacities, and Zone AE is the flood insurance rate zone that corresponds to the general operation guidelines for the major reservoirs which regulate flow 100-year (toodplains that are determined in the Flood Insurance on both the Weber River and East Canyon Creek. The operat i onal Study by approximate methods . Whole-foot base flood elevat ions information is applicable to flood frequency analysis for the Morgan Ci t y derived from the detai led hydraulic anal yses are shown at selected study . intervals within this zone .
15
14 5. Information obtained from Vaughn Hansen Associates, Salt Lake City, Walatch Front and Central Utah Flood Control Study was prepared by Vaughn Utah, 1984. Hanlen Allociates for the coe (Reference 19) . Thls report was a reconnaislance level flood control study and, therefore, did not contain 6. Simons, Li 6: Associates, Inc., Weber River and East Canyon Creek detailed background informat i on on hydrology. Values for the SO- and Hydrology for City of Horgan. Utah, January 1985 . lOO-year recurrence interval discharges at Morgan were given as 4,900 cfs and 6,000 cfs, respectively. 7. U.S. Department of the Aro y, Corps of Engineers, Design Memorandum No . 1. Weber River! Utah , Channel Improvement Horgan to Ogden, The Bureau of Reclamation published Dam Failure Inundation Study . echo December 196t. Dam. Weber River Proiect . Utah in 1984 (Reference 20). Echo Dam is located approximately 16 miles upstream of Horgan City. Regional 8. Federal Emergency Hanagement Agency, Flood Insurance Study hydrology was used to determine the i nflow design flood. The results Cuidel i nes and Specifications for Study Contractors. September 1985. were used only for comparison, due to the general nature of the hydrology analysis . 9 . U.S. Department of the Inter ior, Geological Survey, Salt Lake City Office, Methods for Estimating Peak Discharge and Flood Boundaries Plood Insurance Studies were published for the surround i ng Count ies of of St reams in Utah, 1983. Davis (Reference 21), Salt Lake (Reference 22), and Weber (Reference 23) a. well as the City of Morgan City (Reference 1). This study agrees wi th 10. U.S. Department of the Interior, Ceological Survey, Fe deral Hi ghway the above-mentioned Plood Insurance Studies. Administration, Computer Program Water Surface Profile (WSPRO),
A Flood Ha~ard Boundary Map was publ i shed for Sunvfti t County t Utah It. u. S. Department of the Inted or, Geolog ica 1 Survey, and Federal (Reference 24) . This study agrees with the Summi t County Flood Hazard Highway Administration, Office of Research and Development, Bridge Boundary Hap . Waterways Analysi s! Research Report, 1985.
A Flood Hazard Boundary Hap was published for t he unincorporated areas of 12. U. S. Department of the Interior, Geological Survey, Techniques of Morgan County, Utah (Reference 16) . Because of the more detailed and Water Resources Investigat i ons . Measurement of Peak Discharges at current nature of the hydrologic analysis, this Fl.ood Insurance Study Culverts by Indirect Methods, 1968. supersedes the data presented on the Flood Hazard Boundary Haps on the Weber River, East Canyon Creek, Deep Creek, and Cottonwood Creek. 13. U.S . Department of the Interior, Ceological Survey, Techniques of Water Resources Investigations. Measurement of Peak Discharge at Dams by Indirect Methods, 1961. 8.0 LOCATION OF DATA 14. U.S. Department of the Interior, Geological Survey, 7.S Minute Information concerning the pertinent data used i n t he preparation o[ this Series Topographic Haps, Scale 1:24,000, Contour Interval 40 f e et: study can be obtained by contacting the Natural and Technological Hazards Big Dutch Hollow, Utah 096l), Photorevised (975); Bounti f ul Peak, Division, FeKA, Denver Federal Center, Building 710, Box 2S267, Denver, Utah (952), Photorevised 0969 & 1915); Bybee Kno ll , Utah, Colorado 80225-0267. Orthophoto; Coalville, Utah (967); Devils Slide, Utah (961), Photorevised (197S); Durst Mountain, Utah, Orthophoto; East Canyon Reservoir, Utah (196l), Photorevised (197S); Fort Do ug l as, Utah 9.0 BI BLIOGRAPHY AND REFERENCES (963), Photorevised 0969 & 1915); Franc i s Canyon, Utah (964); Heiners Creek, Utah (1964); Henefer, Utah (1964); Horse Ridge, Utah 1. Federal Emergency Management Agency, Flood Insurance Study . City of 096B), Photo inspected (975); Lost Creek Dam. Utah (964), Photo Morgan City. Utah, July 16, 1981. inspected (197S); Horgan, Utah (1961), Photorevised (l97S); Moun t ain Dell, Utah 096ll, Photorevised (915); Peck Canyon, Ut ah 096B); 2. U.S. Department of Convnerce t Bureau of the Cen s us, 1980 Cen s us of Peterson, Utah (19S5), Photorevi sed (1969 & 1975); Portervi It e, Utah Population. Utah, January 1982. 096l), Photorevised (915); Shearing Corral, Utah (968); Snow Basin, Utah (955), Photorevised (975); Warship. Utah (967). 3. U.S . Department of Agriculture, Soil Conservat i on Service and Forest Service, Soil Survey of Morgan Area , Utah, Horgan County and Eastern l5. Landmark Happing Ltd. , Lakewood, Colorado, Photogrammetric Happing, Part of Weber County. Scale 1: 4,800 , Contour Interval 2 feet, November 1984.
4. U.S. Department of the Army, Corps of Engineers, Sacramento l6. Federal Emergency Hanagement Agency, Flood Hazard Boundary Map . Di strict, Wasatch Front and Central Utah Flood Control Study, Horgan County. Utah I Unincorporated Areas, February 14 t 1978. unpubl i shed.
17 16 17. Gingery Associates, Inc., Weber River Hydrology. Davis and Weber Counties, Utah, 1979.
18. u.s. Department of the Ar~y, Cor ps of Engineers, Report on Reservoir Regulation for Flood Control - Weber Basin Reservoirs, July 1971.
19. u.s. Department of the Army, Corps of Engineers, Sacramento District, Wasatch Front and Central Utah Flood Control Stu~. unpublished.
20. U.S. Bureau of Reclamation, Salt Lake City, Dam Failure Inundation Study, Echo Dam, Weber Riv~~ Project, Utah. March 1984.
21. Federal Emergency Management Agency. Flood Insurance Study, Davi s County, Utah, Unincorporated Areas. March 1. 1982.
22. Federal Emergency Management Agency. Flood Insurance Study. Salt Lake County, Utah, Unincorporated Ar ~-!. December 18. 1985.
23. Federal Emergency Management Agency, Flood Insurance Study, Weber County, Utah, Unincorporated Areas, July 19. 1982.
24. Federal Emergency Management Agency. Flood Hazard Boundary Map, Summit County, Utah, Unincorporated Areas, January 3, 1978.
18 ,..,....--,----r-----~--,. . .,,.!
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STREAM DISTANCE IN HUNDREDS OF FEET ABOVE CONFLUENCE WITH COTTONWOOD CREEK 06P •• _ •••. J" i" ~ ...... I _. .'--1",. I .... I' • I ! ,. . ! I 4918 .• 1 ...... - --_ .• 4986 i I ~ ~~! 4910 ' 4980
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CONFLUENCE WITH ~ o OEEPCAEEK ., mil ~ 0~ •..., ___ 4 _____•• _ iii ;: '" z 0 m Z % CD --- - __ - ______--__ ._ C • 0Z o :II .,0m ...0 ~ I ...m : . .\. m \ ~ '" ..~ 0
,I,. I --",' ' .. " • f' ••• t I.··. .... , . • , 0 t , ••• I • 'r'" . .. :. , . I •• , I , " II ••• , I • ,I, ••• ...... ;!':I ~ I • •• , • "I. ~ 1070 ,. 'I ... I • •• :!: t : I' , •• , ·"i· '"
1081 > U ..Z "..C .... - ...Z ='" :I -; h---l+---.-'--l-5G· JO... ~ .:..:..:...: :.•• - o · 10110 ...... ,' C 5~ LEGEND "z =~ t,. I ., IiOO • YEAR FLOOD ~ .. > u " .. 100 . YEAR fLOOD ...z 1, 1_ " I &0 . YEAR fLOOD Isot.; It • I'" t. " II I • 10 · YEAR fLOOD .. :I... il STREAMBED ~ C CROliIECTlON It... LOCATION ...Q 11020 - .;....I .LSO.Li..----SSI "- 171 --N ~81 eto 708 710 711 720 721 730 7311 STREAM DISTANCE IN HUNDREDS Of fEET A.OVE CONfLUENCE WITH COnONWOOD CREEK lOP f·O .. I .. . , •• j ., • -r-. -:- ----r-.. r· .~ -: "~-l '1 I .... " •• .. ." . ••• t ! ., . '. ., . ':'.: I . . , -, .. .1. . I -, . . .. I . , . ... -::~: ~-.:: ...... - -:- -~: -::- -:I : - ~- ~, - Bl15 .: I I .. , i . . : t! I ... ". I .•• · .... , , .. , , _... .. CIt B11 0 f--...... -rh---+t+r , Bll0 .... a:: -tt···'· , , ...... , t" • ! . 1:.::::' ... 'I .'. I ... ;': 0 ~ I' , ',. ,.,' I" . a:: -A. ....CD -0 "::'::l';' ' '-1" .' I Bl08 BlOB f->-t-,..,..-r-r'-I-.I-;...., ;-.-: -~ ~~ (t~: · .. I·· .. ·;::· 0 ~ ::: \: -: .... -: ( ,. 0 I " ... . t::: . '.' . ' .,:.. I .: I:.: . , \. ,., .. ., , ! . • r - -i-':""'.,..J...4-t+J..-;! ' ' r' .. · y~~ - , , I . ., . \ .- . . : .... I .. _._: ...• B0911 ", t, :.:. .! . I I 8090 > ... -- --- '1--- -.. --.I --- -:_, U . : ': : '.. i ...Z : ... I CI • • - • I ....c I : ...z !:;in . I" .. :I -; BO.B f---r----...... t----- ... '1' •• _._ 0._ 50.B ... ~c ...... CI . .. , LEGEND C i: :: .. . Z §~ 600 . YEAR FLOOD ~ > ,+ :;:f···: .,. .., :. : :1':-: • ------100 · YEAR FLOOD u ...Z 50 • YEAR FLOOD CI --- -- II: ...... :-; :. : : ; I :. ------10· YEAR ~ LooD ... f+--+---'---++-,~ ~ ~:; ~ ~ ~ ~. :I ., ., ., .•• , I ...... ,...... STREAMBED it -' ••••••• to ".. • ••• • ~ C ... " .... ;: '::. ". I Vi CROSS SECTION ...II: LOCATION ...0 :--____ ...... ,::-'-:::~,'-.__ . ! . i I . 6 ... 735 740 745 750 755 780 n8 780 7tlB 790 718 800 STREAM DISTANCE IN HUNDREDS OF FEET ABOVE CONFLUENCE WITH COTTONWOOD CREEK llP ; 'I' I , • ---1.. . . • " . t t . .: .'1' •• I, ... : I ...... , .... It • • I .. , ., ... • •• ,:., I •• •.••• 5130 :.:. 1: ...... : ~!~-- 11130 en I • .....~ ca:: . I w.. C ca::~ .. I Ito. ca:: 5125 ... . , • ' 111211 -tI:I c:t ., . I .....C *~ i .. ': .:.. 1 I ~ ;; ! : ...... I . ' I ! I • t I . . ,., ·--··1··:,·· ' 5120 I
! : . I t, • I ~ ~ I , 111111 ...~1I115 ... I 1 I I • ' 5110 5110 u> 1 z , I ... • ,I « I ...z ...... ::::)'" - I I :I... -; 5105 : 7' "I 5105 ... LEGEND «z 5: . i &00 • YEAR FLOOD ~ . I > • t 100 · YEAR FLOOD u I , , ...z 1 I t --- -- 110 · YEAR FLOOD ... .j. • t ...... t :-- ' ...... II: , I 10· YEAR FLOOD ... I· :I ..... " . ! $TREAMIED ...... « II Z . CROI$IECTION ...II: 0 I LOCATION ... I ~'I I J I ... 800 805 810 815 820 825 130 135 140 1411 STREAM DISTANCE IN HUNDREDS OF FEET ABOIIE CONFLUENCE WITH COTTONWOOD CREEK 12P :, :~~1' ~7:~~:F .~::~~~[~-~ ;. - ~: ~- [ ~. ~ ~-~ ~1: .~: ::::~ ... : . - ::: j:: .: ;.' I.' ;'::. "; .1 • •• : ••• :: ••••• :: •• : ••• ::: ::!: . . : : . :: .:: t:. I .,. • •• • •• " • • ••••• I • ••• • • • , • ~ I • I...... Of... •. . ,...... • ...... 1...... :.: :. I 1I0211 1-..,.....-....mi!tt+----'--'-'*-,---- .-----.• - .. -- - •. _ ...... - ..... -...... '.--•.. -- - ... -- --- _.. ... -1 110211 ...... I . .. I L1 ~ }: : ~ i :. :: . ..::-: :. : . :-: 'l : .: : I' .' . >1' .' . . ;:: .:: I' . . :L;::r ::1. .: .. :. : .... : .... ; : ...... '. • ... , .j •• I j'1;' .•. ,I. .• I •• I' • '1'0 ...... " :'~' sM'" .:- I 1102011-'_'..;.1_'_' H~-i--'-'''';'''':'-+'' '" ... ;-::-:-::::: r: ...... : .. :-: -.:.~: ~ :':::'.: :::.:.: -.:. --: j~:: .. -~ ------. 11020 . ,;.' 1 ... ···r .• :i·.·1 ; T . I . .'. . . ~' ...... I' :·:·:·::·!····· ·:::h:: ~. ;:>"!". , --...... --.. 1110111 " I , . I : : . ' : , ; I 1 . I ;
.. :1 ...;. :V ... ~ . · ... 1 11010 I ~ ! . I I . ..•• -t ••••. .• , . . . ~. '. .. 1 . .. - ..~-~- 'r' .. _:'"--_ . .. _- I' .. _-_..:' 110011 ::-···! ·· ~ /~ i·:1 ~ ..-.: '1 ' ~ ... .: .":: I":· 1 • t to I· . ., ... .•• , , ,j...... 'I •.• , /" !. .: '1' . . . . ~ I:' ::: I: I ••••. t '0 • 0.. • •• . . . . , . I .. , .... \ ... I ...... 11000 > I I' . ,': 1 U Z I I w , I I I. "C I I z~ ! w 5;;; I 1 ::E w -; I· .:...... I· 49911 ~c LEGEND "c z ~e , Il00 · YEAR FLOOD ~ i .. > 8 . , ------100 . YEAR FLOOD uz f I I I w , 60 - YEAR FLOOD 4990 .... I .. ----- a: 1 .i· "w : '::: .. 1 ------10 . YEAR FLOOD ::E w I STREAMBED .... Ii ·!C l ~ :: i : 1:: :: I:;:':': C .... 1. I., 1lt ... I. a: .. I ,I I I . CROll SECTION w ,. 1 •• Ii 0 , LOCATION w .l-:....: I I ~. i 6 .. o II 10 111 20 211 30 311 40 411 110 1111 eo STREAM DISTANCE IN HUNDREDS OF FEET ABOVE CONFLUENCE WITH WEBER RIVER l3P ..: ...: : : ~.. 1:_... :
~ ~ 1031 1031 Iii !!:'" ~ >= ~1030 1030 '"
.. , .. I ..... 5020 LEGEND IiOO • YEAR FLOOD ------100 • YEAR FLOOD ----- IiO • YEAR FLOOD ------10 · YEAR FLOOD ~ STREAM liED CROIS SECTION . .. t·· '11 LOCATION t .. ., • • t • ~ + 6 70 75 80 105 110 111 120 125
STREAM DISTANCE IN HUNDREDS OF FEET A.DVE CONfLUENCE WITH WEllE .. RIYER 14P ELEVATION (FEET NGVO) Qt at at 01 01 01 (II g g ~ ~ ~ ~ i o ot 0 01 0 at 0 :;: -- --r------.. j-... t •. - \ _...... I
0 : • e l ~-siF'MOIIGA~ . .:-~ \ . WiRGAN.~ \ .. \ .~ ~ ..: -..:. ~ I .. '" \ \ -- :: •.•• -...t· -! . l', - - .. . \ I . .;: ... :;: - ----: ------, . _.... ------.--- ., 0-- 0\ .:: .. : 1 ·1 ~ :;~ . -- .. - .- _ .. -----
I'bl en .: -\ .:- ~ - .. -----. - - -' ------.-----.----.------. .... '" ,."m ~ C ~ ~ ~ g: ' 0-- -... -- --1 C\.-- . ---.- ..- -- - ~~~~ ---- ... Z % C Z C ..a : '0---.. '-.~- ...... -.. ---- · I ·-·~ ·-- '-''' -- -.. - .--_.- ..... ---.---.-----..------...c ;;: ~'~ em OF MORGA... ',J 'I!:!l 0--' . \ MORGAN eOUNTY 'v' ~ ~ - . _. __ . _. , MORGAN COUNTY " 0 0 , CITY OF MORGAN m< no ...z ~z •- --.- ---.-- n'" co -c..r--~ ~ \ \~\ .. I ~ '"CDm ...... - • .• ------. -"" ------",to ------______" 0 " ~ '0---
...... _.. - '\ '" _.] --_.. ," \ ------. . \ .: .· .... i II 0... -- ,. . . 0I 1 0~ I' : . --'-. .l __ '-: ____. ...:~...:.'.:..:.~i ~ " -\ ~ 'I' I £ !; ;; S - II! Ii\---- \ ~~Ncm ' 1 ,... " 0 . 8 l5 ~ ~C(ffiNiv I iii II gi ; ;:; ;:; .:. .:. . \ ... -- .-- MoaoANCOUNN - --1 at ,. E"" '" 1ft ----- .... ~ """,. \ \ . MOIIOANcm I' :D :D , onz~ c= ,....,. ,..."" ...... , : .
0; L i § § § § _ . \~ ______.. __. '.! o eft 01 01 01 01 01 g ~ ~ ~ ~ i at 0 01 0 at 0
-. FEOERALEMERGENCYMANAGEMENTAGENCY FLOOD PROFILES ~ I MORGAN COUNTY, UT (UIllIICOIIPORATED AREAS) EAST CANYON CREEK ELEVATION IFEETNGVDI i'" ..o'" o '" 'P'!i . lill i L-' . "-r' " .. ".,.I " --" '1" -~""'I'" " --,uT " -' :-=1' .. _'... _" , - ,- I , ' I " I . .... I ~ . .. .. I '=:-: :::j::: ~::::!;::. :-:-: jl: :'~: o! I \ i - I~ ' " : • "'" ... : ::' •• ::.: ::" . \ I . ~ . I '---. l .:.: 1 : ~; ; :" ~'I ~: ~; ~~;:: I 0.. ------... _- 0-' ~ en.... o :JI m J> i: 0 0; ~ z~ ~ 0 .. m Z .MORGAN CITY :z: ~ANcOuNiv c: Z 0 :JI m ~ ~ .-.. - - ~--:-- 0 -- en \ ~ \1 m." \! ~ ~ I J> .. ..for,) -_ ••• __• __ ... _- l' 0 ",I ~l l ol ,... In CI In n Z , \ :JI ~ c; ~ 8 § o In -< -< \ - -- ;'"",-«,.. .. '" m ~I I a!.... In .2Jz> .. m ,. ,. " 21 i~0 o g~ g~ ,..."" ,..."" z o 0 g g o 0 co co co co o o o co co i i .... ~ o co o '" o co FEDERAL EMERGENCY MANAGEMENT AGENCY FLOOD PROFILES en-" "V MORGAN COUNTY. UT (UMIICOIIPORATtil AREAS) EAST CANYON CREEK ------r---.....,-..-.-. :-;-:-;--r'---'" • • • , • ~ f • • • • t I ••••• ,. • .. ·t'., . t,· .•.• ...... t· ·i. ,.. :.. I •• , ••• ••••••• to I .\" •••••• t- • •••• •••• • t _, ••••• • 1 • • ••• eo , •• to •••• - •• -- ••., j ••• ••• -- .. , .1 .•.•...•.. M ~ ... :-: -d <:~: :.: :-; .. --. -+-'.'-: :..c..; :-' -: • +--- . --'-I---~ ... ~ ...J • I ~ 1 U 'I ' 0 B ;+rl'~:~~:~: ~~ .": '.:: ~':f'~:: : : ~.i<;!::::1 - ~ 1 .. z 'i : .j .. :. . ::: .. : ..... 1·.. :: : ...... :.. : ::: .. c ._.II ...... __ _L:_~_:·_ G':'"'''- ,.:. : a u ! •• .•... ;--_.- -- .... ---. 00 ~-:-. . •. - · I· , 1 0 ~ . 'I . I. :.::.:. a M ·1 .••• . 00:: ' ... ' . I .':: ::.: .. ' 00 ' :::" ...J .. ~ 1 : I ,: • : •• 'j : ':-1' ~ • 1 ·l.. 00' .. I _00 _: ...... ___• ", i ,i " . _::.: I; ., !.... , I... , , ... • I· . I .1 1 ~ . I. :,:.'1 , · , 00.. f'" :.,. :l ·I ._.. _~._J··· .:1·.::::: , ...... 'j ":':-",:":' 1 - -+ :~---.I ,I " "~~7'1:--~"-;'1'" : :,1-: . I I I ·1; . .., ,. : 00 I I· . . I I I . I I I to I I 11071 ~.----+ ,. ----.... -- .. ; .. -..... -,-:-- "-:"-1,"---;-" 00 > I I· I: :...... uz . , .1 c:I . , 1 C , . I- I ...z , I I ...a • t· , c:I ~i LfOEND c I z ,. I 100 • YEAII flOOD ~ i > ~m , . I 100 . YEAII flOOD ." ...... ~ I 1 10 . YEAR flOOD c:I 1I0ea - -+---_._...... • t ...... ••• _ 1 ••.• _ C I !.. ~-.. : 10 . YEAR flOOD ...a I ... ITIIEAN lED -'c II C.oa SECT10N c I lOCATION :!l I ~ 2110 21111 280 2111 270 STREAM DISTANCE IN HUNDREDS OF FEET AIOVE CONFLUENCE WITH WEIER RIVER 17P 1710 ,- , , - 1710 I I· ...... .. , . .. . Ino · . , - .. _. _,_0"" Ino I Ii" is , > I I ac: I ~ , I I -, I lit ~ 1710 T-: ...... I r :: > ... li I a ~ I ..: , A. .... , I ~ . ., . -. 1710 -a 1710 _. _-- -- . i -I. a u I ' , I a ~ I ~ ·. z>- ... c u Ci .... > en ~174O 1740 ~ ...~ !!: ! · r ~ ~173O ....•.. - • _••• 11730 ... -. ---I··· . . I .. , , .1 1M : ! . · , ·: ,. ,. , I • r •• - ... - .. 5720 · 5720 >u I z '1' I' 1M I ~ ...z~ · ·, ...a ~i 5710 5710 1:1 LEGEND Cz 5", 100 - YEAR FLOOD i > ------100 . YEAR FLOOD uz III , 110 . YEAR FLOOD I ----- 1:1a: 5700· - " ... III ------10 - YEAR FLOOD a III ITIIEAMBED . ~ ~ ..C II a: . ~ ~ ~ CROII.EeTION LOCATION l!: ~ : ~ 6 ...III 0 5 10 15 20 25 30 31 40 45 50 .. 80 ITIIEAM DIITANCE IN HUNDREDI OF FEET AIOVE EAlT CANYON CIIEEK REIERVOIII l8P .., ~ iii' 0 > ....CII: .." ....en ~ ....CII: ... > 0= 0 CD &. 5. :00: -0 .... 0 CII: 0 (.) -' z: ... 0 >- Z C (.) ....en ...• t · ·· ~ .... " ... • •• ' f ., ...... • i·, ., • ".".'. I .., r+"" • I, t' ••.• :: t :::::: I····'··" , . , •• 010 T • , ~ • · ---i----rr~~_r~--~--~t-,-, -, -. -,-,-.~rl ++-·------+--,-.-,--, -,~.-.-,4 5790 t I'" .; ...... : : : I ! : ~ : t , . j ••• ., ' , .. "" , . .. It,.··· ... . , i I' t •••• ... .. T'- 5780 > .... ••• 1 •• u -~,~-. : -:-, . , z , , ",1"1" .. ,I' :: I;:; t;· . ... ! :. . . . , ...... I·' .•.. C ,., •• f' I' ~ ...... I " . Z.. ~- 2: =:l -_ ..... -tr====::!:====::!:=====;t 5770 .. • , . , ", •• • , I ••• I ... C g~ . • ,,' . t· I" f t ""'" I ' LEGEND Z " , 1 ' " I I • • t •• •••• ••• t . I i. =~ Il00 , YEAR FLOOD i > :: I:: :::' t···· . 100 ' YEAR FLOOD u "j ., '1" • ...... z ,. I ••• ••• IiO ' YEAR FLOOD ..... II: •••••• I _-• 10 , YEAR FLOOD ...... , .. ..2: STREAMBED oJ . , .. . C II .... . C . ... CROSS SECTION ..II: ., LOCATION 0 5750 ,l 1 ..... 80 70 75 80 85 90 95 100 105 110 115 120 STREAM DISTANCE IN HUNDREDS OF FEET A80VE EAST CANYON CREEK RESERVOIR 19P .. . I' •••• .... , + •• , . ---'r- -... I .. , ..•.. ·f···· .. .. -[---1: .:: .. , .. -- ' ...... : . i ... I •• I -.... j ... _.... ·1 ··· ... : ...... : C '~"'-"-.:I . , --.- .,'; . :!:;., . "1' . • ii", !' . . :: "I I I ••••• .. . .. ''', . ,. ' .. ·1 ...... I··· · · ...... 'i: ,.[. ---1-' . _. _. . -- ., en . o' +j••'~':' 1 • ... . iT; .:~:~ . I ·1 , . ,11 \" .. I .... . ! I I I' .. ...o== ••• , . "1'tt'" I'1 ....'" , .. j . , , ,I . I .... 1030 :. ~~;: i , .. : -:~ ~ .. I.:~ ! .. 1. ·1··· .. ·· ··:· . 1 ~: ... :.;.~ -. :.:.- . . 1030 o • I. j f I j ••• 1 , - , . o "', I' ... I I: o ~ .::; I:. I I . I. . , ... .: I ., I , ::. I I : I g I I ,.~ i l020, .:I ...... , .. ~ · 11020 to ! !; I . I ' ~' f I ~ I . ~ I ~1010 :1 ··_· •t o ._ • -,1010 ... l-~ I ~"-' . I ..... ,_ . . I I . . . , . ,! I .• . . I I. - - .. -1-- - - .. - .. , . ---- I . .. ! I ., , I I I ..: .... 1. .. i i 4890 ,. . , 4890 LEGEND .. ' .. , . .!. 100 • YEAR 'LOOD '. "! ------100 . YEAR FLOOD I I ----- 110 • YEAR FLOOD 41110 .. ,~ .. .. ,.. : -: .: .. :... . ! , ------10 · YEAR FLOOD : ".: I: ~ j:.' ~ ITREAMIlED I .•. I., l' I, I CROilIECTION I :: ~: ; I I" . ,.,. " , 6 LOCATION o I 10 111 20 21 30 311 411 10 511 eo STREAM DISTANCE IN HUNDREDS OF FEET AIIOVE CONFLUENCE WITH WEIER RIVER 20P rr~~~~~--rrrr-r-n~--~~--~, t.· .•.--~. r------~----~---r----~--r-----, .....~ ,.~--~-----r------.-~------r------~--...... --~--, &080 • • o •••• . ... , : t:: ., ,0 •• 41 : •• ,I •••• ...... , ... I,· j' . ::::.:: ' . " '; t .. I ' · ...... · ~ ~ ...... · ~ ', • , I .• , ,,' ...... •• -" t· ..- · t+ 0" ,," _, ...... I .... : i ~ : : . t·· .. " , ..... I., ~ . ~. ; . , . • •••• 0 ... . t ' t ' •••• • • .. ... ,. to •• :": ::;:: • t • 'I' •... , "'! , •••• . f····· &0110 , •• ,I. I 'j" • 'I" ••••• I' i! 1" • '" • f'" ., • , .... ••• "".I, ,_ •• · '" , ,.., . . ••••. 0, .!.::::: ; ... .. , ...... ~~ :::: : . .. t··, · ·· • _,0 to ••• -. -~ ._--1------+_ ...... _ - . ------1f-.:-----+!!f.J--"""?~ &070 en ... , ...... , .. . ¥: •• ". I I ••• I. tf •••• ...... =... loW . +., ',.". t··,· • "0 , •••• 0 ~ A- U D. &0110 -0 loW t 0 ~ , ... . , . •• t 1:.1 ...... 0 . ,.,., ... '1" .. , • • •••• • I •• ...... , . _ ... _•• _ . ''-4 __ • _.~ . __ _ • &0&0 · .. .. t· . " ., ...... :·...... 4+...... · ... .. 11040 •• t I . . · 6. .· . . •••• • 1 ..... ••••• I •• I • ••• &030 ...>- Z 1:1'" ...« I ., Z ~- ::E'" ='" : ~-'.. -. -: !. :-. --.. --I· 5020 '" -; «1:1 ~C LEGEND Z z: CI ":.:: I·. :.! =~ IiOO • YEAR FLOOD ~ ::::: .:: ,',: .:.: I >- 100 · YEAR FLOOD ------...Z ------1iO · YEAR FLOOD 1:1'" . . . II: ------10 · YEAR FLOOD &010 h--., ~:;; -4-: It:l-+-'~j'-r-· .ll· ~·· '-:~ ' l-:"'::: 'j " -_. -._. '"::E f ::- I ITREAMIIED '".... -r-J'-"'J'-- ~ II « :!::::.::'. 0 :.. :.... . C CROSS SECTION II: LOCATION '"0 L--'-'-• • , 'I..:...... LJ __.. ______I 6 ..'" 110 " ~ n ~ " ~ 100 lOll 110 118 120 125 &TAEAM DISTANCE IN HUNDREDS OF FEET AIIOVE CONFLUENCE WITH WUER RIVER 21P T • _ •• . . _. r_. --:--:-'1' -_. - --~- -llllO 11110 ...--•.- .•~.~,-r\ -."'T~-:'-'-' ~---:-.. l' I • ,. I· " ••• , •• • ••••• I i ... I " , . , , • ,t 1 I' .... I • I ...... \ I ":: ':,": . .: II I • . I ' ::::':~~1 fl'::::!; :'. i I. , •••• I' ". .. . 0 i '" 1140 c i" . T , ·.:.-1-······· --_. ·-1140 c I I II: ! ~ ...0 .E I , I IE , I I . I . - - . -_. I_ .... - .•.•' ••.• • _ .••• , 1130 lit .. ~ --t .. •• ..... , .. 1130 . ~ I • I ... I , ...J !i ...... :.c , Q .... , CII: • I . : ,I. U , , ., &. CL ., :':.:! ... I' · .. , 1120 -Q ...... I' liD -...... f-' .. _-:. , • . :. , Q .... Q CI ...... J I ~ , I' 1:15110 1 . I . 1110 ~ I ~ I ~ .,1 , ~lIloo .. : ...... _.... ! . , , 1100 ... I I ~ , I I , .. I 1 ! '" :!:: :!'.: I ••.. t ,I II" •• I . .1 I, ... , .. ' 5090 > 5090 i' ,. I U Z i I . 1:1'" , C .. :0 z~ Sin '":I .; 1080 , t.======;i5080 1:1'" ~C LEGEND Cz c ~e .! 100 • YEAR FLOOD :I , , > . 100 · YEAR FLOOD u ., Z ~I , tIO ' YEAR FLOOD 1:1'" - . I . 10· YEAR fLOOD '" .. ..J !.:1 .....• :.i; Jxb :I'" '" II . , STREAM liED -' C I" • a: .. H ! . I J CROSS SECTION I , LOCATION '"C ~ , ... 6080 I '" 121 130 135 140 145 150 186 110 1811 170 175 110 STREAM DISTANCE IN HUNDREDS Of FEET AIOVE CONfLlJENCE WITH WEI!R RIVEII 22P •... • • ELEYATlON• (FEET NOVD• l • : ..w ...... ~ o ~ ------·o 0 CI o ~ -:: 1 ~;: i :~ ~ -1 1- 0' ,. "' '" . __ . 1 OJ. ··--·-·i_~ c~~~~~~ _ ~~~:~.:' . ~ :1 l 1-· 0-: co ------t-+ ------.------t 0-- j: ·o ~ m CD m ..:II __ .. - __ - I,<: co "' ..il •I:"' 0 OJ... z• ~ 0 "'Z %c: Z 0 :: 0_0.___ • _____ • _'_.0 __ :II •"'0 ...0 "- ..."' '" • !; 0• < 0- c:0"' """Aft !lOAD z 0- e... "'z =------0 -, !'" ...% \ - ~ - > \ •"' 0• - '. '":II :II ~ <: '":II e- ....!VAft !tOAO • ------'" li e- ~--- ~ I" \ - I: -----~ :!l Il O :' : ~~. ---i- _ :_~_~ ;_~_~_~_L~l i : . . : : I: : I I I :;; C) \ \ \ - - -- n.~g "' r:ll il c;> _ 8 § ~ : 11 '" -< -< - - a-1::i I ;: ;: ~ ~ - ----\ ------, i~ II: ~ ~ ~ ~ \ i08r~~ \ I I o § 8 8 COUNTT !lOUTE337 -, ... IL...... 00 '\. ~ 0 •... • • • • • w .. ..GO ...... 0 ~ o o.. '"o ..o FEDERAL EMERGENCY MANAGEMENT AGENCY FLOOD PROFILES ~ MORGAN COUNTY, UT " (IIIIIICOIIPORATED AREAS) COTTONWOOD CREEK 1-' • II .... - --r'- . . , T I ...... \ .. ' , .. 1 1--1 ••••••• t· ~ : . : : . : 1r ' ' • • ••• 1 " , I •• • • I I, T':' :, " II" r , I , . i· .: I 4140 .... !..... 0-._ .... _. . ----' 4140 • • I ' 0 •• I t .,I I , , . i I ¥ 4.30 .. i . -...... _-, .. -_ . • _. 4130 ..,In w ~ ~ ... U , 0 § i .. ,I, 4120 .. i .t ...... _.. -. , 4.20 -0 0 I 0 i ~ 1= I ... B ~ I ~ 4110 ' , 4110 .... \OJ \OJ ~ , ! I I' i4900... 1. 1-· .. I' .900 -' I ., \OJ I: ,. ,I 4890 .890 u> Z \OJ ...."C ...Z ~- ~ :I =»'" ...0 ... .880 -i LEGEND "zC c 5c 1iOO · YEAR FLOOD :I > ------100 , YEAR FLOOD u , ...Z ----- 150 • YEAR FLOOD . i "a: T ------10 · YEAR FLOOD .. :I... I STREAMBED ... I ~ C a: II CROSS SECTION ... ~ LOCATION ...Q 6 "- 10 15 70 75 80 85 .0 85 100 105 110 115 STREAM DISTANCE IN HUNDREDS OF FEET ABOVE CONFLUENCE WITH WEBER RIVER 24P -2- ~~~-~-. ------,~-:• I -'--r-~-:-'-r------• • ,. r~-'• • - ~ I, --, ...... - .. . "1 / . I· " "'1 . ".,. :.::',::: I" , :;. :.;:: ':.' I .enD -:- -- • --1--- --~·t· .. - -; ...... -.-.:..: ... -: --~-:...:.:t··: ~.: ·1:·- ----1 •• t r J .' i' ''1' , i: : .. , i . i.··1 I I ', . ! I' . lit :.: 1000 .,I .j: . ! . - .. --. -- .. --- .. -I .... -- - 50e0 Yo! , ...... Yo! , 1 CIC I U I I ..0== Q .,.... ., I . , :. :' I I , I A. 8 I , : .::'·1 0 4HO . i I0IO , ... : .l .... 5050 - ,.---+.-- : . :-:---1 : -: .. !.... I 0 I ,.... I , . 0 ~ , .. , .... Q , .. U i i 41eo I ICMO' 5040 ... ; ::I I - !!: I ~ .. " . I >.170 - '::- .-- ,.,. . '-"'j' 5030 ~ ... ~ 1M •• , 1 ! • ,. I ., •• ,£.. t' . t •• / t·, .. •••. . I, . I ...... -.. ... 11020 > : 10, u •• lO f·--··-:': .... Z , ...... , I ..c I, z... Sin ~ 5010 ~ _...... ! .. . 4110 ....., -; 4150 1 c I LEGEND z ~c I I, _ • YEAR FLOOD ~ =m I > I ------100 · YEAR FLOOD uz 8~ ...... I ...... , z~ • I •• : •.• I ----- 10 . YEAR FLOOD ,. 4MO ...II: ------10 · YEAR FLOOD :II il ~ .. ... ~- ITREAMUD ..J !: : ~ C CROII.ECTION ...II: ~ LOCATION ..Q • 830 1 • ...:.:: .•. i ..J 6 ... 115 120 125 130 1,. 140 141 1io 110 1 .. 110 1 .. 170 175 ITREAM OIlTANCE IN HUNDREDI 0' fEET AIOVE CONflUENCE WITH WEIER RIVER 25P ..,en lIII:: "'"~ :::!.... u ..0 § 1110 -0 I 0 0 ~ ....-' 8 ~ 1"00 ~ III III !!: ...... • , • • •• l' •••• , • ~ . •• • ••••••••• . . ~ . . . ~ .. ~,...... •••... + ,'•••• , ...... " •••• •• • ...... t...... ,.,. 0" ...... , ...... " .. ,.,' , .... '! .. •• , •••• 1 ...... I ", ... , LEGEND •••• ,. 1 ..•• !. , . IGO • YEAII FLOOD ...... 100 • YEAII FLOOD ...... ,' . 10 • YEAII FLOOD .", .. ,. 10· YEAII flOOD " .l ... '" :::;:::.: • • d •• ,. , _ ~. ~. '.::. ~ ,,: t. :.:::.::: t I.. I' ITlIEAM lIED ...... , : ;:: I:::: •••• ; •• '1 •••••• I •• : Nt : :!:: ...... ,••••.. "."1. '" .. ,...... "" I 6 CIIOUIECTION ...... LOCATION , "' ... :: :i: j!:: ',','. ',1', '. ,". .. ~~'~'~'~'~'~'1'~'~'~'~'~'~'1'~'~'~'~======~ 110 ,.1 200 STlIEAM DlaTANCE IN HUNDREDS OF FEET ABOVE CONFLUENCE WITH WEIER IIIVER 26P EXHIBIT 3: tlL!VATION R.EPERENC! HARKS (Cont'd) EXHIBIT 3: EL!VATION REPER!IICE HARKS Reference Blevat· o:\ Reference Elevation (feet I!CVD) Delcription of Location Hark (feet NGVO) Delcl"iption of Location --'!I!.L- 8MI 5,123.06 USC6GS bench IlArk K-135, located 16.5 feet 8M 10 4,967.56 Chiseled era,s on right bank. upstream north of fence, 63 feet south of railroad ving",all at entrance to Dalton Creek tracK, 142 feet louthwelt of Farm Road at siphon under Cateway C~nalt located Interltate 84 oVel"pa.l, 2.9 miles east approzill'l4teLy 2.2 miles north-northwest of northealt of Moraan County Court House. Hilton. 8M2 5,091.84 .. USC6GS bench mark H-135, located just RH Il 4,961.98 Chi.eled square on northeaat corner of south of Union Pacific Railroad, 21.S feet louthealt ving",al1 of Route 591 bridge northealt of first telephone pole • over ,...... , I\y Canal, located approximately • southw~lt of railroad mi lepost 961, 1.2 m...... south-southeaat of Route 591 approximately 0.5 mi le northeast of Como bridge over Weber River at Peterson. Springl Road at Weber River east of Morgan. 'UI 12 4,8B9.83 Nail on top of lurvey stake on teLephone pole a' northwest corner of intersect ion 8M3 5,063.51 USGS bench ..ark F-135, located on Horgan of Route 591 and County Road, County Court House grounds t 1 feet north approxi m,f\ tely 300 feet welt-southwes t of northealt of sidewalk., 34 feet southeast Route 591 bridge over Weber River at of base of war memor i al t 1\1 feet south of Peterson. louthealt corner of Court House in Mo r gan. 8M 13 4,&64.12 Top of nail 0.8 foot below railroad spike 8M4 5,110.12 Nail on top of survey stak.e on telephone on west gate r oat of Farm Service Road, pole 15 feet .outh of State Highway 65 approx.imately 100 feet southwest of Union b~idge crosling of East Canyon Cw- eek, 1.0 Pacific «ailroad. approxim.atel ;f l.2 miles mile upstream from Ea s t Canyon Reservoir. not' th-northwes '" of Route S9 1 bridge over Weber River at Pe terson. 8M5 5,129.25 Chiseled crall painted red on top of large yellow-painted rock on east side of State RH 14 4,942 . 03 Ntl i l on top of stake on ut i 1 i ty po le Highway 65, approximately 500 feet north located approximatel y 300 feet southeast of entrance to r.:::reational area at upper of Cottonwood Creek, 0.9 mile northeast of fJnd of east Canyon Reservoir. Route 591 bridge over Cottonwood Creek at Hountain Creen. 8M6 5,061.33 Northwest corner anchor bolt at west end of south bridge railing of Young Street 8M I~ 4,871.14 Top of ri ght bank uplt ream bridge abutment bridge over ealt Canyon Creek at Morgan. where Route S91 crolses Cottonwood Creek at Mountain Creen. 8M 1 5,045.00 Railroad spike 1.4 fee t above ground in telephone pole on the west side of Oeep 8M 16 4,834 . 98 USC&CS bench mark F, a square hole in the Creek, 40 feet north of Route 591 bridge top of the southwest corner of the east over Deep Creek at Li ttl eton. conc r ete abutmen t of Un i o n Pacif i c Railroad bridge over Dry Creek, 2 fee t 8M8 5,002.61 USC6GS bench mark 8-135, located 44 feet below the track, 9 feet sO ll th o f south northwelt of Stoddard Lane overpass of rail, approximately 1.0 mile we s t Union Pac i fie Rail road and (nterstate 84, southwest of Hounta i n Green. approximately 60 feet nO l theast of railroad at Stoddard. 8M 11 4,834. 61 BrOn:l~e cap. s tamped 3FK,c , on northwes t corner of Un ion Pac. i f i.. Ra it road bridge 8M9 4,916.10 Chiseled square on left bank do..mstream over Dry Creek. approx i mately 1.0 mile wingwa11, at angle joint in conc.rete of west-southwest of Mountain Creen. Stoddard Diversion Dam located 0.9-mile west of Stoddard.