eau claire county, wisconsin - starr team · eau claire county, wisconsin, and incorporated areas ....

EAU CLAIRE COUNTY, WISCONSIN, AND INCORPORATED AREAS Community Name

Community Number

Altoona, City of 550126

Augusta, City of 550127 Eau Claire County, Unincorporated Areas 555552

Eau Claire, City of 550128

Fairchild, Village of 550129

Fall Creek, Village of 550130

PRELIMINARY

Federal Emergency Management Agency FLOOD INSURANCE STUDY NUMBER

55035CV000B

NOTICE TO

FLOOD INSURANCE STUDY USERS Communities participating in the National Flood Insurance Program have established repositories of flood hazard data for floodplain management and flood insurance purposes. This Flood Insurance Study (FIS) may not contain all data available within the repository. It is advisable to contact the community repository for any additional data. The Federal Emergency Management Agency (FEMA) may revise and republish part or all of this Preliminary FIS report at any time. In addition, FEMA may revise part of this FIS report by the Letter of Map Revision (LOMR) process, which does not involve republication or redistribution of the FIS report. Therefore, users should consult community officials and check the Community Map Repository to obtain the most current FIS components. Initial Countywide FIS Effective Date: February 18, 2009 Revised Countywide FIS Date: PRELIMINARY

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TABLE OF CONTENTS

Page 1.0 INTRODUCTION 1

1.1 Purpose of Study 1

1.2 Authority and Acknowledgments 1

1.3 Coordination 3 2.0 AREA STUDIED 4

2.1 Scope of Study 4

2.2 Community Description 7

2.3 Principal Flood Problems 7

2.4 Flood Protection Measures 8 3.0 ENGINEERING METHODS 8

3.1 Hydrologic Analyses 9

3.2 Hydraulic Analyses 13

3.3 Vertical Datum 18 4.0 FLOODPLAIN MANAGEMENT APPLICATIONS 19

4.1 Floodplain Boundaries 19

4.2 Floodways 20 5.0 INSURANCE APPLICATIONS 31

6.0 FLOOD INSURANCE RATE MAP 31

7.0 OTHER STUDIES 33

8.0 LOCATION OF DATA 33

9.0 BIBLIOGRAPHY AND REFERENCES 33

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TABLE OF CONTENTS - continued

Page

FIGURES FIGURE 1 – FLOODWAY SCHEMATIC 21 TABLES TABLE 1 – INITIAL AND FINAL CCO MEETINGS 4 TABLE 2 – FLOODING SOURCES STUDIED BY DETAILED METHODS 5 TABLE 3 – FLOODING SOURCES PREVIOUSLY STUDIED BY DETAILED METHODS 5 TABLE 4 – LETTERS OF MAP REVISION 6 TABLE 5 – SUMMARY OF DISCHARGES 12 TABLE 6 – SUMMARY OF STILLWATER ELEVATIONS 13 TABLE 7 – SUMMARY OF ROUGHNESS COEFFICIENTS 18 TABLE 8 – FLOODWAY DATA TABLES 22 TABLE 9 – COMMUNITY MAP HISTORY 32

EXHIBITS Exhibit 1 - Flood Profiles Bridge Creek Panel 01P Chippewa River Panel 02P – 09P Chippewa River Overflow Channel Panel 10P Eau Claire River Panel 11P – 13P Elk Creek Panel 14P Lowes Creek Panel 15P – 18P Sherman Creek Panel 19P – 22P Exhibit 2 - Flood Insurance Rate Map Index Flood Insurance Rate Map

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FLOOD INSURANCE STUDY EAU CLAIRE COUNTY, WISCONSIN AND INCORPORATED AREAS

1.0 INTRODUCTION

1.1 Purpose of Study This Flood Insurance Study (FIS) revises and updates information on the existence

and severity of flood hazards in the geographic area of Eau Claire County, Wisconsin, including the Cities of Altoona, Augusta, Eau Claire, the Villages of Fairchild, Fall Creek, and the unincorporated areas of Eau Claire County (hereinafter referred to collectively as Eau Claire County). Please note that the City of Eau Claire is geographically located in Chippewa and Eau Claire counties, and only the portion of the city within Eau Claire County is shown in this FIS. Also, the City of Altoona and the Villages of Fairchild and Fall Creek did not have previous FIS text.

This FIS aids in the administration of the National Flood Insurance Act of 1968 and

the Flood Disaster Protection Act of 1973. T his FIS has developed flood risk data for various areas of the county that will be used to establish actuarial flood insurance rates. This information will also be used by the communities of Eau Claire County to update existing floodplain regulations as part of the Regular Phase of the National Flood Insurance Program (NFIP), and will also be used by local and regional planners to further promote sound land use and floodplain development. Minimum floodplain management requirements for participation in the NFIP are set forth in the Code of Federal Regulations at 44 CFR, 60.3.

In some States or communities, floodplain management criteria or regulations may

exist that are more restrictive or comprehensive than the minimum Federal requirements. In such cases, the more restrictive criteria take precedence and the State (or other jurisdictional agency) will be able to explain them.

1.2 Authority and Acknowledgments

The sources of authority for this FIS are the National Flood Insurance Act of 1968

and the Flood Disaster Protection Act of 1973. This FIS was prepared to include the unincorporated areas and incorporated

communities within Eau Claire County in a countywide FIS. Information on t he authority and acknowledgment for each jurisdiction included in this countywide FIS, as compiled from previously printed FIS reports, is shown below.

Augusta, City of:

For the May 4, 1989 FIS report, the hydrologic and hydraulic analyses for this study were performed by the U.S. Geological Survey (USGS) for the Federal Emergency Management Agency (FEMA), under Inter-Agency Agreement No. EMW-85-E-1823, Project Order No. 14. T hat work was

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Augusta, City of: (continued)

completed in January 1987 (Reference 1).

Eau Claire, City of: For the July 17, 1984, FIS and the January 17, 1985 Flood Insurance Rate Map (FIRM), the hydraulic analysis was prepared by Ayres Associates for FEMA, under Contract No. EMW-E-0288. T he hydrologic analysis for Sherman Creek applicable below US Highway 12 was completed by Ayres Associates, and the discharge-frequency values for the Chippewa and Eau Claire Rivers were provided by the U.S. Army Corps of Engineers (USACE), St. Paul District, and the Wisconsin Department of Natural Resources (WDNR). That work was completed in May 1982. For the February 4, 1998, FIS, the hydrologic and hydraulic analyses for the Chippewa River were obtained from a floodplain study that was prepared by the City of Eau Claire (Reference 2). The hydrologic and hydraulic analyses for portions of the Chippewa River along Lake Hallie were obtained from the FIS for the unincorporated areas of Chippewa County (Reference 3). T he hydrologic and hydraulic analyses for portions of Sherman Creek, Lowes Creek, and Otter Creek were obtained from the FIS for the unincorporated areas of Eau Claire County, dated August 16, 1993 (Reference 4). The digital base map information was provided by the City of Eau Claire’s City Engineer. Additional information was derived from mapping prepared to support the hydrologic and hydraulic analyses of the Chippewa River and the previously compiled FIRM for the City of Eau Claire.

Eau Claire County Unincorporated Areas:

The hydrologic and hydraulic analyses for the Chippewa River and Sherman Creek were performed by the USACE, St. Paul District, for the FEMA, under Inter-Agency Agreement No. EMU-86-E-2226, Project Order No. 10. This work was prepared in October 1987 and updated April 1992. T he hydrologic and hydraulic analyses for portions of

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Eau Claire County Unincorporated Areas: (continued)

Sherman Creek were performed by Ayres Associates in May 1982. The hydrologic and hydraulic analyses for Lowes Creek, Otter Creek, and portions of the Eau Claire River were taken from the Eau Claire County FIRM (Reference 4). T he hydraulic analyses for the Eau Claire River in the vicinity of Lake Altoona were prepared by the WDNR. The hydrologic and hydraulic analyses for Lake Eau Claire were taken from the Floodplain Management Study for Lake Eau Claire. That work was completed in April 1984 (Reference 5). The hydrologic and hydraulic analyses for Elk Creek were taken from the FIS for the Unincorporated Areas of Dunn County, (Reference 6).

For the 2009 countywide FIS, digital conversion of special flood hazard areas was performed by CDM Federal Programs Corporation (CDM), under contract HSFE05-05-D-0027/002. This work was completed September 26, 2006. The digital base mapping information was provided in digital format by Eau Claire County. Information used for this study was provided in digital format by Eau Claire County. Aerial photography is dated 2000 with a 1-meter resolution. Users of this FIS should be aware that minor adjustments may have been made to specific FIRM base map features. This countywide FIS includes new hydrologic and hydraulic analyses for Lowes and Sherman Creeks. The analyses for this study were performed by Wisconsin DNR for FEMA under Mapping Activity Statement Contract No. WI-10-01. This study was completed in September 2012. The coordinate system used for the production of this FIRM is Universal Transverse Mercator (UTM), North American Datum of 1983 (NAD 83), GRS 80 spheroid. Differences in the datum and spheroid used in the production of FIRMs for adjacent counties may result in slight positional differences in map features at the county boundaries. These differences do not affect the accuracy of information shown on the FIRM.

1.3 Coordination

The initial Consultation Coordination Officer (CCO) meeting for this countywide FIS was held on January 31, 2011, and attended by representatives of WDNR and community officials. These meetings are held to explain the nature and purpose of a FIS and to identify the streams to be studied by detailed methods. A final CCO

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meeting was held on ########## with representatives from FEMA, the communities and WDNR to review the results of the study. All problems raised at that meeting have been addressed in this study. For the 2009 countywide FIS, a pre-scoping report was prepared by Michael Baker Jr. Inc., dated March 2005. This report described work performed by WDNR to assemble the necessary information to perform the redelineation of special flood hazard areas based on improved topographic information. The initial coordination meeting was held July 26, 2005, and was attended by representatives of CDM, WDNR, FEMA and the community.

The results of the study were reviewed at the final CCO meeting held on May 23, 2007 and attended by representatives of CDM, WDNR, FEMA and the community. All problems raised at that meeting have been addressed in this study.

The dates of the initial and final CCO meetings held for Eau Claire County and the incorporated communities within its boundaries are shown in Table 1, “Initial and Final CCO Meetings.”

TABLE 1 – Initial And Final CCO Meetings

Community Name Initial CCO Date Final CCO Date City of Augusta * June 14, 1988 City of Eau Claire June 14, 1979 January 25, 1983 Eau Claire County Unincorporated Areas

October 1986

September 26, 1991

Village of Fall Creek * * *Information not available

For the February 4, 1998 F IS revision for the City of Eau Claire, the city was notified by letter dated February 10, 1995 that FEMA would be revising its FIS.

2.0 AREA STUDIED

2.1 Scope of Study

This countywide FIS covers the geographic area of Eau Claire County, Wisconsin including the incorporated communities listed in Section 1.1. The areas studied by detailed methods were selected with priority given to all known flood hazard areas and areas of projected development and proposed construction.

All or portions of the flooding sources listed in Table 2, " Flooding Sources Studied by Detailed Methods," were previously studied by detailed methods as listed in Table 3 “Flooding Sources Previously Studied by Detailed Methods”. The 2012 work superseded all areas of the original scope and study for Lowes and Sherman Creeks on the reaches indicated. The limits of detailed study are indicated on the Flood Profiles (Exhibit 1) and on the FIRMs (Exhibit 2).

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TABLE 2 – Flooding Sources Studied By Detailed Methods

Flooding Source Limits of Detailed Study Lowes Creek Sherman Creek

From its confluence with the Chippewa River upstream to County Highway HH From 300 feet below State Highway 312 to the Eau Claire/Chippewa County line

TABLE 3 – Flooding Sources Previously Studied By Detailed Methods Flooding Source Limits of Detailed Study Bridge Creek From approximately 200 feet downstream of

State Highway 27 to the City of Augusta's eastern corporate limits with Eau Claire County Unincorporated Areas

Chippewa River From the Eau Claire-Dunn County line to the Eau Claire-Chippewa County line

Chippewa River Overflow Channel From its confluence with the Chippewa River to its divergence from the Chippewa River

Eau Claire River From its confluence with the Chippewa River to approximately 1000 feet upstream of its confluence with Sixmile Creek

Elk Creek From the Dunn County boundary, south of West Folsom Street to the Dunn County boundary, north of Anderson Drive

Lake Eau Claire From the dam near Highway 27 to the upstream extent of Lake Eau Claire

Lowes Creek From its confluence with the Chippewa River upstream to Interstate Highway 94

Otter Creek From the City of Altoona corporate limits upstream to Interstate Highway 94

Sherman Creek From its confluence with the Chippewa River to the Eau Claire-Chippewa County line

The areas studied by detailed methods were selected with priority given to all known flood hazard areas and areas of projected development and proposed construction.

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All or portions of the Adams Creek, Bears Grass Creek, Beaver Creek, Beeman Creek, Big Creek, Black Creek, Bridge Creek, Browns Creek, Clear Creek, Coon Creek, Coon Fork Creek, Deinhammer Creek, Diamond Valley Creek, Eau Claire River, Elk Creek, Fall Creek, First Trestle Creek, Fivemile Creek, Graham Creek, Grass Creek, Hathaway Creek, Hay Creek, Horse Creek, Lindsay Creek, Lowes Creek, McGarver Creek, Muskrat Creek, Ninemile Creek, North Fork Eau Claire River, Otter Creek, Pea Creek, Peeso Creek, Pine Creek, Rock Creek, Sand Creek, Schoolhouse Creek, Sevenmile Creek, Shambaugh Creek, Simes Creek, Sixmile Creek, South Fork Eau Claire River, Swim Creek, Taylor Creek, Thompson Valley Creek, Travis Creek, Valley Creek, West Creek, Whippoorwill Creek, Willow Creek, Wolf River and several unnamed tributaries of the aforementioned streams were studied by approximate methods. Approximate analyses were used to study those areas having a low development potential or minimal flood hazards. The scope and methods of study were proposed to, and agreed upon by, FEMA and Eau Claire County.

For the 2009 countywide study, the flood boundaries of all flooding sources previously studied by detailed or approximate methods were digitized from effective FIRMs and portions of Chippewa and Eau Claire Rivers were redelineated based on updated topographic information. Several areas of approximate flooding were extended in order to match the approximate flooding across community corporate limits within Eau Claire County and across the county boundary from contiguous counties. The hydraulic analysis for a portion of the Chippewa River, starting from the Dunn County boundary, up to Interstate 94, was revised by the WDNR. The hydraulic analysis for a portion of Sherman Creek was revised from its confluence with the Chippewa River to 800 feet upstream of Menomonie Street. This hydraulic analysis was revised by Owen Ayres & Associates, Inc. in 1995 for WiDOT. This FIS also incorporates the determinations of letters issued by FEMA resulting in map changes (Letter of Map Revision [LOMR], Letter of Map Revision-based on Fill [LOMR-F], and Letter of Map Amendment [LOMA]). Incorporated LOMR cases are as shown in Table 4, "Letters of Map Revision." All Letters of Map Revision (LOMRs) and Letters of Map Amendment (LOMAs) incorporated in this study are summarized in the Summary of Map Actions (SOMA) associated with this FIS update. Copies of the SOMA may be obtained from the Community Map Repository.

TABLE 4 – Letters Of Map Revision

Community Flooding Source/Case Number Date Issued Type

Eau Claire County Lowes & Pine Creeks / 10-05-6594P 8/31/2010 102-D

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2.2 Community Description Eau Claire County is in west-central Wisconsin, about 50 miles north of the City of Lacrosse, Wisconsin, and about 70 m iles east of the City of Minneapolis/St. Paul, Minnesota. The county is bordered on the west by Dunn and Pepin Counties, Wisconsin; on the north by Chippewa County, Wisconsin; on the east by Clark County, Wisconsin, and on t he south by Trempealeau, Buffalo, and Jackson Counties, Wisconsin. The population of Eau Claire County was 98,736 in 2010, 93,142 in 2000, 85,183 in 1990, and 78,805 in 1980 (Reference 7). Eau Claire County is served by Interstate 94 and U.S. Highways 12 and 53, and the Chicago and North Western Railroad. The City of Eau Claire serves as the principal trade center for west-central Wisconsin's dairyland. A number of large manufacturing, industrial, and commercial enterprises are located in the county. The climate in west-central Wisconsin is moderate and is characterized by wide and frequent variations in temperature. Average annual temperature is 44 degrees Fahrenheit (°F) with monthly averages varying from 71 °F in July to 13 °F in January. Annual average precipitation in the region is 30.5 inches with an average recorded snowfall of 47 inches (Reference 8). The Chippewa River, which is the major flooding source in the county, and drains 9,480 square miles, rises in the northern Wisconsin lake region. At Eau Claire, the Chippewa River drains about 6,630 s quare miles, including the Eau Claire River drainage area of about 880 s quare miles. The river flows to the south through northwestern Wisconsin to its confluence with the Mississippi River. The basin is relatively flat, with numerous lakes and swamps in the headwater regions and rolling farmlands and cutover wooded areas in the middle and lower reaches. The topography was formed by glacial activity which left thick sedimentary deposits in the lower portion of the basin that thin out toward the northeast.

2.3 Principal Flood Problems Flood producing storms in the Eau Claire region are of two types: one consists of long duration, moderately heavy rainfall that covers large areas, and the other involves short duration, heavy thunderstorms of a more localized character. Major floods on the Chippewa River in the Eau Claire area are generally the result of the large-area, prolonged storms. Spring floods associated with snow melt and limited rainfalls occur frequently; but, the major floods of record have all been the result of summer storms. Residential, commercial, public, and light industrial properties at several points along the Chippewa River are subject to flooding. For example, commercial properties located along the downstream portion (near the mouth) of the Eau Claire River and along the east bank of the Chippewa River in the vicinity of Grand Avenue are affected by the larger floods. At Half Moon Lake, major floods could overtop Menomonie Street, flood the low lying land on w hich light industries and residences are located, and raise the lake level to submerge part of Carson Park.

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Two of the most severe floods of recent records on the Chippewa River at Eau Claire occurred following the August 28-31, 1941, r ainfall storm and in April 1967. The 1941 flood rose rapidly, beginning during the early hours of August 31, and crested during the afternoon of September 1 at a peak flow of approximately 102,000 cfs. Discharges were above bankfull capacity for approximately 4 days. At the peak of the flood, numerous commercial, residential, public, and industrial properties were flooded; these inundated areas included the university grounds and old wastewater disposal plant. All roads crossing the river but the Grand Avenue bridge were closed to traffic. Another serious flood occurred in April 1967 with estimated peak flows of approximately 93,000 cfs. Heavy rainfalls on June 5 and 7, 1980, produced a flood with approximately a 71-year return period on S herman Creek. Peak flows for this flood have been estimated to have been 2,550 c fs as based upon a detailed hydrologic analysis. Flooding of some residences along Sherman Creek upstream of Clairemont Avenue occurred in 1980, as well past years.

2.4 Flood Protection Measures

The county has implemented a number of local flood protection measures. The local measures may provide some degree of protection during the more frequent flood events, but there are no e xisting structural measures that are known to protect against the 1-percent annual chance flood. The Eau Claire wastewater treatment plant along the Chippewa River near the downstream corporate limits of the City of Eau Claire has a levee system that completely protects the plant from floods in excess of the 2-percent annual chance flood. The City of Eau Claire has a floodplain ordinance, which restricts development in the designated 1-percent annual chance floodplain areas.

3.0 ENGINEERING METHODS For the flooding sources studied in detail in the county, standard hydrologic and hydraulic

study methods were used to determine the flood hazard data required for this FIS. Flood events of a magnitude which are expected to be equaled or exceeded once on the average during any 10-, 4-, 2-, 1-, or 0.2-percent annual chance period (recurrence interval) have been selected as having special significance for floodplain management and for flood insurance rates. These events, commonly termed the 10-, 25-, 50-, 100-, and 0.2-percent floods, have a 10-, 4-, 2-, 1-, and 0.2-percent chance, respectively, of being equaled or exceeded during any year. A lthough the recurrence interval represents the long term average period between floods of a specific magnitude, rare floods could occur at short intervals or even within the same year. The risk of experiencing a rare flood increases when periods greater than 1 year are considered. For example, the risk of having a flood which equals or exceeds the 1-percent annual chance flood (1-percent chance of annual exceedence) in any 50-year period is approximately 40 percent (4 in 10), and, for any 90-year period, the risk increases to approximately 60 pe rcent (6 in 10). The analyses reported herein reflect flooding potentials based on conditions existing in the county at the time of completion of this FIS. Maps and flood elevations will be amended periodically to reflect future changes.

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3.1 Hydrologic Analyses

Hydrologic analyses were carried out to establish the peak discharge-frequency relationships for the flooding sources studied in detail affecting the county.

For each community within Eau Claire County that had a previously printed FIS report, the hydrologic analyses described in those reports have been compiled and are summarized below. Pre-Countywide Analyses:

For Bridge Creek, hydrologic analyses were carried out to establish the peak discharge-frequency relationships. E quations were developed by the USGS for estimating the magnitude and frequency of floods for streams in Wisconsin (Reference 9). T he 1-percent annual chance peak flood discharge equation for streams located in northwestern Wisconsin was used to estimate the 1-percent annual chance peak discharge. For the reach of the Chippewa River in the City of Eau Claire, when the river begins to overflow the channel banks upstream of the wastewater treatment plant, the river flows through two bridges; one on each side of the wastewater plant. The bridge located most northerly of the wastewater plant is often termed the "overflow channel." This overflow channel acts solely as a supplemental conveyance structure for flood flows. The summation of flows for both main channel and overflow channel equals the "full river section" approach and exit sections. The hydrologic analysis for the Chippewa River within the City of Eau Claire was revised in the February 4, 1998 FIS, and was obtained from a floodplain study that was prepared by the City of Eau Claire (Reference 2). Gage data were reanalyzed by the St. Paul District of the USACE, resulting in lower discharges for the Chippewa River (Reference 32). T he hydrologic analyses for the portion of the Chippewa River along Lake Hallie were obtained from a study done for the unincorporated areas of Chippewa County (Reference 3). The discharges for the Chippewa River in the unincorporated areas of the county were determined at USGS gage stations applying log-Pearson Type III statistical analyses to determine the discharge-frequency relationships (Reference 32). The discharges for the Eau Claire River within the City of Eau Claire were primarily computed by statistical analyses of available stream gaging records. The discharges were adopted from studies performed by the USACE St. Paul District, Ayres Associates and WDNR (References 10, 11, and 12). The hydrologic analysis for Otter Creek was obtained from the FIS for the unincorporated areas of Eau Claire County (Reference 4). Discharge-frequency relationships on Sherman Creek were developed at the Clairemont Avenue and the U.S. Highway 12 bridges based upon consideration of the results obtained using the following methods:

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1) Conger's regression equations using drainage area, main channel slope, and lake and marsh area as independent variables (Reference 13).

2) Weighted regional regression equations using drainage area, main channel

slope, and lake and marsh area as independent variables. 3) Regional weighted regression analysis using drainage area as the single

independent variable. 4) U.S. Department of Agriculture, Soil Conservation Service (SCS) TR-20

watershed computer program using the SCS 24-hour Type II storm (Reference 14). A 6-hour storm was also computed.

5) TR-20 watershed analysis using the derived normalized temporal pattern for

a 24-hour storm. 6) Drainage area comparison to USGS stream gage No. 5-3645 using the

optimum drainage area exponent derived from method 4. The possible effect of storage behind roadway constricting structures was evaluated by routing the adopted flood hydrographs through the cross drainage structures in the studied reach. The roadway structures located at U.S. Highway 12 a nd the upstream Clairemont Avenue crossing of Sherman Creek were the only locations where there was found to be a significant reduction in flood peak discharge. Further analysis of the U.S. Highway 12 crossing using the TR-20 model indicated that less than 2-percent reduction in flood discharge results from the impoundment of water behind U.S. Highway 12. To analyze the "split flow" condition between the upstream Clairemont Avenue bridge and the mouth of Sherman Creek, runoff hydrographs were developed. The term "split flow" as applied here refers to the fact that part of the flow from Sherman Creek flows overland directly to the Chippewa River, i.e., west of Clairemont Avenue, rather than following the typical valley section flow regime whose distances are plotted on water-surface profile sheets. A representative hydrograph for this analysis was computed by applying the SCS dimensionless unit hydrograph ratios to the flood peak discharge and the determined time to peak. The flood volumes of the hydrographs were determined by applying the average watershed runoff curve number value for Antecedent Moisture Condition II to the 6-hour precipitation amount having the same exceedence probability as the peak discharge being selected. A runoff hydrograph for the June 1980 f lood event was also computed to correlate the historical high water marks with computer water-surface profiles. The adopted discharge-frequency relationships for Sherman Creek were developed based on weighted results obtained from methods discussed above. For the portion of Sherman Creek that was annexed from the unincorporated areas of Eau Claire County, the discharges used were developed for the FISs for the unincorporated areas of Eau Claire County and the City of Eau Claire (Reference 2).

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The 2009 Countywide Analyses:

No hydrologic analyses were conducted for the streams within Eau Claire County as part of this countywide revision. This Countywide Analyses: A new hydrologic analysis was performed by the Wisconsin Department of Natural Resources (WDNR) in 2012 for the Lowes Creek Watershed and Upper Sherman Creek. Discharges were computed using the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) computer software, version 3.5.0 (Reference 33). F or each subbasin, runoff Curve Numbers (CNs) were estimated using SSURGO soils data and the WISCLAND landuse data (1992). Times of concentration were estimated using the TR-55 flowpath segment method. The rainfall distribution used was developed by the WDNR and is based on large storms in the State of Wisconsin from 1975 to 2003. For Sherman Creek;

1) Critical Duration of rainfall was also looked at to determine what duration of storms produced the highest peak discharge. Below the Chippewa/Eau Claire County boundary, the 96-hour storm was used. Above the county boundary, the 24-hour storm was used.

2) Flood storage was taken into account in two locations along this stream. The reaches modeled as storage reservoirs are regulated stormwater ponds or floodway areas. It is assumed that no major construction or filling will occur in these areas that would reduce the amount of available storage volume.

For Lowes; 1) Critical Duration of rainfall was also looked at to determine what

duration of storms produced the highest peak discharge. The 7-day storm was used throughout the entire reach.

2) Flood storage wasn’t taken into account. 3) For the reach of Lowes Creek below the STH 37 bridge, when flow

begins to overflow the left overbank, it leaves the Lowes Creek channel and enters directly into backwaters of the Chippewa River. This reduces the flow that enters the Chippewa River via the Lowes Creek channel. The summation of flows for both the main channel and the overflow channel equals the “full river section”, the same flow at STH 37 bridge.

The hydrologic method used for the approximate studied areas involved the use of the State of Wisconsin's multiple regression equations for ungaged basins. The derivation of these equations, the applicability, and the assumptions involved are described in Estimating Magnitude and Frequency of Floods in Wisconsin by J.F. Walker & W.R.Krug (Reference 34). These equations use basin size, main channel slope, soil permeability, and an areal factor as independent variables.

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A summary of the drainage area-peak discharge relationships for all of the streams studied by detailed methods is shown in Table 5, “Summary of Discharges”.

TABLE 5 – Summary of Discharges

Peak Discharges (cubic feet per second)

Flooding Source and Location

Drainage Area

(square miles)

10-Percent Annual Chance




0.2-Percent Annual Chance

BRIDGE CREEK At State Highway 27 35 * * * 2,650 *

CHIPPEWA RIVER

At Interstate 94 6,630 71,170 * 100,280 112,970 143,960

Downstream of the confluence of the Eau Claire River

6,620 71,000 * 100,000 113,000 143,500

At confluence of the Eau Claire River

5,710 67,600 * 94,200 106,000 132,800

CHIPPEWA RIVER - OVERFLOW CHANNEL

At wastewater treatment plant

* * * 2,300 5,700 18,200

EAU CLAIRE RIVER

At confluence with the Chippewa River

887 20,350 * 32,600 38,400 53,600

At confluence of Otter Creek

* 17,500 * 28,000 33,000 46,100

ELK CREEK * * * 3,500 4,100 *

LOWES CREEK

¼ mile Upstream of eastern I-94 Crossing 59.6 2,466 3,813 4,747 5,563 8,045

At Confluence with Willow Creek 52.4 2,312 3,515 4,348 5,064 7,220

At Confluence with Pine Creek 42.6 2,085 3,118 3,839 4,444 6,209

At Confluence with Clear Creek 35.2 1,736 2,602 3,235 3,748 5,243

At CTH HH 23.6 1,217 1,822 2,246 2,596 3,632

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TABLE 5 – Summary of Discharges (continued)

Peak Discharges (cubic feet per second)


Drainage Area

(square miles)






SHERMAN CREEK

At Clairemont Avenue bridge 19.7 1,345 * 2,315 2,800 4,145

Downstream of U.S. Highway 312 15.5 1,135 * 1,955 2,365 3,505

At Railroad Bridge 14.2 935 1,370 1,719 2,197 2,976

Below Outlet of Menard Strormwater Ponds 13.6 876 1,315 1,680 2,128 2,839

Above Confluence with Menard Strormwater Ponds 9.7 1,034 1,289 1,588 1,888 2,475

*Data not available

The stillwater elevation was determined for the 1-percent annual chance flood for Lake Eau Claire, and is provided in Table 6, "Summary of Stillwater Elevations."

TABLE 6 – Summary of Stillwater Elevations

ELEVATION (Feet NAVD)







LAKE EAU CLAIRE

* * * 911 * *Data not available

3.2 Hydraulic Analyses

Analyses of the hydraulic characteristics of flooding from the sources studied were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. Users should be aware that flood elevations shown on the FIRM represent rounded whole-foot elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the Floodway Data tables in the FIS report. For construction and/or floodplain management purposes, users are encouraged to use the flood elevation data presented in this FIS in conjunction with the data shown on t he FIRM.

Locations of selected cross sections used in the hydraulic analyses are shown on the Flood Profiles (Exhibit 1). F or stream segments for which a floodway was

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computed (Section 4.2), selected cross section locations are also shown on t he FIRM (Exhibit 2).

Flood profiles were drawn showing the computed water-surface elevations for floods of the selected recurrence intervals.

For each community within Eau Claire County that has a previously printed FIS report, the hydraulic analyses described in those reports have been compiled and are summarized below. Pre-Countywide Analyses: For the backwater analyses of Bridge Creek, cross sections were obtained from field survey. Additional cross sections were estimated from adjacent surveyed sections and topographic maps (Reference 15). Structural geometry and elevations for bridges were also obtained from field survey.

The starting water-surface elevations were determined by the slope-conveyance method. Water-surface elevations for the 1-percent annual chance flood were computed using WSPRO, a step-backwater program (Reference 16). For the portions of the Chippewa River, Eau Claire River and Sherman Creek within the unincorporated areas of the county, the elevations, cross sections, and structural geometry data were obtained from field surveys. The starting water-surface elevations used for the Chippewa River and Elk Creek analyses in the unincorporated areas of the county were based on water-surface profile data presented in the Dunn County, Wisconsin FIS (Reference 6). Water surface elevations of the selected recurrence intervals for Chippewa River were computed using the HEC- 2 step-backwater computer program (Reference 17). For the portion of the Chippewa River in the City of Eau Claire, water surface elevations were started approximately 5 miles downstream of the city’s corporate limits using data from the county and other studies (References 11 and 18). Upstream of Dells Dam, the starting water-surface computations were based on an elevation-discharge rating curve of an old timber dam, which is approximately 150 feet upstream of Dells Dam. This timber dam caused higher water-surface elevations during high flow periods than if it was not in place (References 10 and 19). The top elevation of Dells Dam is at the normal pond level. The actual top of the dam is at elevation 806.9 feet with a gate sill elevation of 733.9 feet. Upstream of Dells Dam, the river profiles are based on hi storical flood records and previous studies, because the river makes a sharp bend within the "lake type" flow regime area of the river (References 10, 20 and 21). Between Grand Avenue and the footbridge downstream, the flows from the Chippewa River flood First Avenue. Sensitivity studies to evaluate whether this area was in the flood fringe versus the floodway were done. The results of the analysis showed that the impacts would be minimal and in agreement with then current State laws.

15

When the Chippewa River reached approximately 771.9 feet, flow from the river entered the overflow channel adjacent to the wastewater treatment plant. The discharges for the split flow into the overflow channel in the area of the wastewater treatment plant are recorded in Table 5, “Summary of Discharges.” Since the energy grade line of the flows at the entrance and exit sections of the overflow channel, for full river flow conditions must be equal, a series of trial computations for various discharges for the main and overflow channel sections were done. The overflow and main channel discharges versus energy grades were then plotted. The flows that balanced with the energy grade lines were used for the final flow distribution and subsequent verification of water-surface profile elevations. For February 4, 1998 revision, cross sections for the Chippewa River and the restudied portion of Sherman Creek within the City of Eau Claire were determined using aerial photographs at a scale of l"=100', with a contour interval of 2 feet (Reference 2). The methodology used to determine starting water-surface elevations and water surface elevations of selected recurrence intervals in the prior study was maintained. Starting water-surface elevations on the Eau Claire River in the City of Eau Claire were determined by the slope-area method. Cross section data and pertinent bridge data for the Eau Claire River were a combination of previous survey data and cross sections from a previous study. The data used from the previous FIS started at the mouth of the river, and stopped upstream of the Dewey Street bridge. The additional cross section and bridge data upstream of Dewey Street were surveyed in the fall of 1980 to supplement bridge drawings obtained from the U.S. Highway 53 project from the Wisconsin Department of Transportation (Reference 25). Starting water surface elevations for the reach of Sherman Creek in the unincorporated areas of the county were based on data presented in the study done for the City of Eau Claire (Reference 8). T he water surface elevations of the selected recurrence intervals were computed using HEC-2 step backwater computer program (Reference 17). For the reach of Sherman Creek in the City of Eau Claire, water-surface elevations between the upstream Clairemont Avenue bridge and the mouth were computed using HEC-2 and Puls routing analysis method to account for the split flow condition that exists. A HEC-2 analysis was made from the mouth of Sherman Creek upstream to Clairemont Avenue to compute the wedge storage that exists in this area; flood flow storage in this area is not at uniform elevations. The Puls routing was made to account for reduction in flood peak flows due to any storage available. Input to the computer program used for Puls routing consisted of inflow hydrographs and elevation-storage-outflow data. The starting water-surface elevations at the mouth are based upon slope-area method and low Chippewa River conditions. Results of the HEC-2 analysis were used to develop the wedge storage available downstream of Clairemont Avenue. The storage curve for the Puls routing was developed at the railroad, Menomonie Street, and at Clairemont Avenue. Flows into Half Moon Lake were added to the downstream railroad rating curve values to obtain the composite rating curve for used in the routings.

16

Flow was assumed to overflow into Half Moon Lake at elevation of 774.0 feet; thus, if this levee was raised, even higher elevations could be expected in flooded areas before flows enter Half Moon Lake. The Sherman Creek analyses did not account for the possible effects of blocked bridge openings, such as occurred in June 1980 a nd might occur during future high flow periods when brush and other debris clog the upstream faces of the bridges. The historical 1980 flood water-surface profiles were matched assuming blocked conditions that occurred, as well as flow into Half Moon Lake. FEMA guidelines require that water-surface profiles be developed for open channel (unblocked) conditions. Thus, it was necessary to deviate from the historical flood analysis for the theoretical floods. The routing and backwater results indicate that: (1) the 10-percent annual chance flood peak flow would not be attenuated due to storage; (2) flow is within the main Sherman Creek channel; and (3) no flow would enter Half Moon Lake. The 2-percent annual chance flood would be attenuated approximately 0.04 foot; that is, the storage available affects the routing only slightly at this frequency. At the 1-percent and 0.2-percent annual chance flood frequencies, storage would have no effect at all; however, the flow into Half Moon Lake is significant and does affect the water-surface levels. In short, the lake acts as a p artial safety valve downstream of Clairemont Avenue in reducing the water-surface elevations. The routing and HEC-2 analyses provided the starting water-surface elevations at the upstream side of Clairemont Avenue. A comparison of the modeled 1980 flood to recorded high water marks showed close agreement. The effect of debris blocking the flow at the railroad bridge was investigated. Two conditions were looked at: (1) complete blockage of the channel area such that only weir flow is allowed; and (2) blockage of all but 75 percent of the area within the left two spans of the structure. The latter condition approached the actual June 1980 event; the results indicated that the 1-percent annual chance flood would be approximately 0.87 foot higher for condition (1) and 0.65 f oot higher for condition (2) at the upstream side of the Clairemont Avenue bridge than if no obstruction blockage occurred at the railroad bridge. In short, documented historical events show that debris, and thus blockage of hydraulic structures (i.e., bridges), impede the flows and result in higher water-surfaces than with open channel conditions. Despite the extensive analysis for the lower portions of Sherman Creek, the analysis was valid only for low flows along the Chippewa River. The water-surface profiles in Exhibit 1 showed that backwater from the Chippewa River had a significant effect in this area. For City of Eau Claire’s February 4, 1998 FIS revision, portions of Sherman Creek were annexed from the unincorporated areas of the county; the cross section, elevation, and structural geometry data were obtained from field surveys. The starting water-surface elevations for Sherman Creek were based on data presented in previous study (Reference 23), and the water-surface elevations were computed using the HEC-2 model (Reference 17).

17

The 2009 Countywide Analysis:

The original HEC-2 model for the Chippewa River starting at the Dunn and Eau Claire County boundary, upstream to Interstate 94 was converted to HEC-RAS model (Reference 24) by WDNR. This new HEC-RAS model was utilized for floodplain boundaries, profiles and FDTs for Chippewa River.

The hydraulic analysis for Sherman Creek was revised to incorporate Clairemont Avenue road improvements completed in 1991. As part of this improvement the flows were rerouted through a 560’ long box culvert along the southwest side of Clairemont Avenue to bypass Half Moon Lake. This model was revised by Owen Ayers and Associates, Inc. and was utilized for profiles and FDTs for Sherman Creek starting from its confluence with the Chippewa River to 800 feet upstream of Menomonie Street. This Countywide Analysis: Channel cross sections were obtained from field survey for Lowes and Sherman Creeks. The City of Eau Claire’s 2007 2-ft topographic data and DTM was used for the Lowes and Sherman Creeks overbank areas (Reference 35). Structural geometry and elevation data for bridges and road sections were obtained from field survey. Water-surface elevations for floods of the selected recurrence intervals for Lowes Creek were computed through use of the USACE HEC-RAS computer program. A new HEC-RAS model was created for Lowes Creek and the Lowes Creek Overflow Channel, extending from County Highway HH to the confluence with the Chippewa River. The Lowes Creek Overflow Channel extends from 2,100 feet downstream of Wisconsin Highway 37 to the confluence with Taylor Creek. Starting water surface elevations for Lowes Creek and Lowes Creek Overflow Channel were determined using the 10-year water surface elevation of the Chippewa River.

Water-surface elevations for floods of the selected recurrence intervals for the Sherman Creek were computed through use of the USACE HEC-RAS computer program. A new HEC-RAS model was created for this reach of Sherman Creek, starting below US Highway 312 in Eau Claire County and extending upstream to the Sherman Creek headwaters upstream of State Highway 29. The starting water surface elevation for Sherman Creek is based on the existing flood study on Sherman Creek in Eau Claire County below US Highway 312. Roughness factors (Manning's "n") used in the hydraulic computations were chosen by engineering judgment and were based on field observations of the streams and floodplain areas. Table 7, “Summary of Roughness Coefficients,” shows the channel and overbank “n” values for all streams studied by detailed methods.

18

TABLE 7 – SUMMARY OF ROUGHNESS COEFFICIENTS

Stream Bridge Creek

Channel “n”

0.035-0.042

Overbank “n”

0.038-0.060 Chippewa River Chippewa River Overflow Channel Eau Claire River Elk Creek Lowes Creek Sherman Creek

0.024-0.033 *

0.030 0.025-0.060 0.04-0.055 0.033-0.045

0.060-0.140 *

0.080-0.090 0.030-0.120 0.04-0.190 0.035-0.160

* Data not available

Except where ice-jam analyses were performed, the hydraulic analyses were based on unobstructed flow. T he flood elevations shown on the profiles are thus considered valid only if hydraulic structures remain unobstructed, operate properly, and do not fail.

3.3 Vertical Datum

All FIS reports and FIRMs are referenced to a specific vertical datum. The vertical datum provides a starting point against which flood, ground, and structure elevations can be referenced and compared. Until recently, the standard vertical datum in use for newly created or revised FISs and FIRMs was the National Geodetic Vertical Datum of 1929 (NGVD 29). With the finalization of the North American Vertical Datum of 1988 (NAVD 88), many FIS reports and FIRMs are being prepared using NAVD 88 as the referenced vertical datum.

Flood elevations shown in this FIS report and on the FIRM are referenced to the NAVD 88. These flood elevations must be compared to structure and ground elevations referenced to the same vertical datum. S ome of the data used in this revision were taken from the prior effective FIS reports and FIRMs and adjusted to NAVD88. The datum conversion factor from NGVD29 to NAVD88 in Eau Claire County is 0. For additional information regarding conversion between the NGVD and NAVD, visit the National Geodetic Survey website at www.ngs.noaa.gov, or contact the National Geodetic Survey at the following address:

Vertical Network Branch, N/CG13 National Geodetic Survey, NOAA Silver Spring Metro Center 3 1315 East-West Highway Silver Spring, Maryland 20910 (301) 713-3191

http://www.ngs.noaa.gov/

19

Temporary vertical monuments are often established during the preparation of a flood hazard analysis for the purpose of establishing local vertical control. Although these monuments are not shown on the FIRM, they may be found in the Technical Support Data Notebook associated with the FIS report and FIRM for this community. Interested individuals may contact FEMA to access these data. To obtain current elevation, description, and/or location information for benchmarks shown on this map, please contact the Information Services Branch of the NGS at (301) 713-3242, or visit their website at www.ngs.noaa.gov.

4.0 FLOODPLAIN MANAGEMENT APPLICATIONS

The NFIP encourages State and local governments to adopt sound floodplain management programs. T o assist in this endeavor, each FIS report provides 1-percent-annual-chance floodplain data, which may include a combination of the following: 10-, 2-, 1-, and 0.2-percent-annual-chance flood elevations; delineations of the 1- and 0.2-percent-annual-chance floodplains; and a 1-percent-annual-chance floodway. This information is presented on the FIRM and in many components of the FIS report, including Flood Profiles, Floodway Data tables, and Summary of Stillwater Elevation tables. Users should reference the data presented in the FIS report as well as additional information that may be available at the local community map repository before making flood elevation and/or floodplain boundary determinations. 4.1 Floodplain Boundaries

To provide a national standard without regional discrimination, the 1-percent-annual-chance flood has been adopted by FEMA as the base flood for floodplain management purposes. T he 0.2-percent-annual-chance flood is employed to indicate additional areas of flood risk in the community. For each stream studied by detailed methods, the 1- and 0.2-percent-annual-chance floodplain boundaries have been delineated using the flood elevations determined at each cross section. Between cross sections within Eau Claire County, the boundaries were interpolated using topographic maps at a scale of 1:24000 with a contour interval of 20 and 10 feet (Reference 15 and 22). For the City of Eau Claire, the 1- and 0.2-percent annual chance floodplain boundaries for the Chippewa River and the restudied portion of Sherman Creek were interpolated between cross sections using aerial photographs at a s cale of 1”=100', with a contour interval of 2 feet (Reference 2). For the 2009 c ountywide study, the 1- and 2-percent annual chance floodplain boundaries were digitally converted from the previously effective FIRMs except for a section on the Chippewa River, located in Township 26N, Range 10W, Sections 4-8, and a section on t he Eau Claire River, located in Township 27N, Range 8W, Sections 17-20. These reaches have been delineated using digital base map information provided by Eau Claire County. T his data includes orthophotography and contours at two foot intervals from year 2000, reference to the Wisconsin State Plane coordinate system, NAD 83 horizontal datum and NAVE 88 vertical datum.

http://www.ngs.noaa.gov/

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The 1- and 0.2-percent annual chance floodplain boundaries are shown on the FIRM (Exhibit 2). On this map, the 1-percent annual chance floodplain boundary corresponds to the boundary of the areas of special flood hazards (Zones A and AE), and the 0.2-percent annual chance floodplain boundary corresponds to the boundary of areas of moderate flood hazards. I n cases where the 1- and 0.2-percent floodplain boundaries are close together, only the 1-percent annual chance floodplain boundary has been shown. S mall areas within the floodplain boundaries may lie above the flood elevations but cannot be shown due to limitations of the map scale and/or lack of detailed topographic data. For the streams studied by approximate methods, only the 1-percent annual chance floodplain boundary is shown on the revised FIRM (Exhibit 2).

4.2 Floodways Encroachment on f loodplains, such as structures and fill, reduces flood-carrying capacity, increases flood heights and velocities, and increases flood hazards in areas beyond the encroachment itself. One aspect 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 assist local communities in this aspect of floodplain management. Under this concept, the area of the 1-percent annual chance 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 1-percent annual chance flood can be carried without substantial increases in flood heights. Minimum federal standards limit such increases to 1.0 foot, provided that hazardous velocities are not produced. However, Wisconsin has established a more strict policy and does not allow any increase in the regional flood height for flood-fringe developments. The floodways in this FIS are presented to local agencies as minimum standards that can be adopted directly or that can be used as a basis for additional floodway studies.

The floodways presented in this FIS were computed for certain stream segments on the basis of equal conveyance reduction from each side of the floodplain. Floodway widths were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. T he results of the floodway computations are tabulated for selected cross sections (Table 8). The computed floodways are shown on the FIRM (Exhibit 2). In cases where the floodway and 1-percent annual chance floodplain boundaries are either close together or collinear, only the floodway boundary is shown.

Portions of the floodways for Chippewa River, Eau Claire River, Elk Creek and Sherman Creek extend beyond the county boundary.

Near the mouths of streams studied in detail, floodway computations are made without regard to flood elevations on the receiving water body. Therefore, "Without Floodway" elevations presented in Table 8 for certain downstream cross sections of the Eau Claire River and Lowes Creek are lower than the regulatory flood elevations

21

in that area, which must take into account the 1-percent annual chance flooding due to backwater from other sources.

Encroachment into areas subject to inundation by floodwaters having hazardous velocities aggravates the risk of flood damage, and heightens potential flood hazards by further increasing velocities. A listing of stream velocities at selected cross sections is provided in Table 8, "Floodway Data." In order to reduce the risk of property damage in areas where the stream velocities are high, the community may wish to restrict development in areas outside the floodway. The area between the floodway and 1-percent annual chance 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 1-percent annual chance by more than 1.0 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 1, “Floodway Schematic.”

FIGURE 1 – FLOODWAY SCHEMATIC

CROSS SECTION DISTANCE1 WIDTH(FEET)

SECTIONAREA

(SQUAREFEET)

MEANVELOCITY(FEET PERSECOND)

REGULATORY WITHOUTFLOODWAY

WITHFLOODWAY INCREASE

CHIPPEWA RIVERA 256,310 8,875 78,291 1.6 761.4 761.4 761.4 0.0B 260,160 4,458 50,477 2.9 762.5 762.5 762.5 0.0C 264,060 2,364 27,137 4.6 763.8 763.8 763.8 0.0D 269,060 3,447 36,520 3.1 765.8 765.8 765.8 0.0E 271,610 3,816 38,500 3.0 766.7 766.7 766.7 0.0F 273,885 4,667 42,827 2.7 767.4 767.4 767.4 0.0G 276,150 5,769 58,353 2.3 768.3 768.3 768.3 0.0H 283,140 4,583 36,970 3.1 770.4 770.4 770.4 0.0I 286,940 5,136 49,817 2.3 771.6 771.6 771.6 0.0J 291,920 4,789 66,111 2.0 772.4 772.4 772.4 0.0K 295,400 891 16,639 7.1 772.7 772.7 772.7 0.0L 296,850 834 13,086 8.6 773.2 773.2 773.2 0.0M 298,500 1,530 21,970 5.1 774.6 774.6 774.6 0.0N 300,250 953 18,060 6.3 774.8 774.8 774.8 0.0O 300,565 529 13,325 8.5 774.8 774.8 774.8 0.0P 301,315 697 17,121 6.6 775.4 775.4 775.4 0.0Q 302,915 1,085 23,945 4.7 776.0 776.0 776.0 0.0R 303,465 778 17,664 6.4 776.1 776.1 776.1 0.0S 303,640 696 16,555 6.8 776.1 776.1 776.1 0.0T 303,750 669 13,712 8.2 776.1 776.1 776.1 0.0U 304,640 646 13,029 8.7 776.3 776.3 776.3 0.0V 306,015 917 16,106 7.0 776.7 776.7 776.7 0.0W 307,065 1,200 17,005 6.6 777.1 777.1 777.1 0.0X 308,115 796 14,476 7.8 777.4 777.4 777.4 0.0Y 308,765 575 12,751 8.9 777.9 777.9 777.9 0.0

1FEET ABOVE MOUTH

1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD 88)FLOODWAYFLOODING SOURCE

FEDERAL EMERGENCY MANAGEMENT AGENCY

EAU CLAIRE COUNTY, WI AND INCORPORATED AREAS

FLOODWAY DATA

CHIPPEWA RIVER

TAB

LE 8


SECTIONAREA

(SQUAREFEET)




CHIPPEWA RIVER(CONTINUED)

Z 309,290 653 12,204 9.3 777.9 777.9 777.9 0.0AA 310,115 600 12,626 8.9 778.3 778.3 778.3 0.0AB 310,573 567 13,749 8.2 779.4 779.4 779.4 0.0AC 310,865 693 13,612 8.3 779.4 779.4 779.4 0.0AD 311,361 740 15,091 7.5 780.4 780.4 780.4 0.0AE 311,640 860 15,770 7.2 780.4 780.4 780.4 0.0AF 313,015 764 14,389 7.9 780.6 780.6 780.6 0.0AG 313,749 557 14,119 8.0 781.5 781.5 781.5 0.0AH 314,215 532 13,512 8.4 781.5 781.5 781.5 0.0AI 314,721 483 12,999 8.7 781.7 781.7 781.7 0.0AJ 315,165 479 12,875 8.8 781.8 781.8 781.8 0.0AK 315,993 458 11,461 9.2 782.0 782.0 782.0 0.0AL 316,161 500 10,950 9.7 782.1 782.1 782.1 0.0AM 316,257 516 12,572 8.4 782.5 782.5 782.5 0.0AN 316,821 666 17,473 6.1 783.3 783.3 783.3 0.0AO 317,091 597 15,817 6.7 783.3 783.3 783.3 0.0AP 317,249 570 14,864 7.1 783.3 783.3 783.3 0.0AQ 318,176 520 13,393 7.9 783.3 783.3 783.3 0.0AR 319,056 527 13,028 8.1 783.7 783.7 783.7 0.0AS 319,876 722 22,952 4.6 784.6 784.6 784.6 0.0AT 320,540 655 14,106 7.5 784.6 784.6 784.6 0.0AU 321,006 565 11,472 9.2 784.6 784.6 784.6 0.0AV 321,676 586 13,673 7.8 785.2 785.2 785.2 0.0AW 322,726 722 16,631 6.4 796.7 796.7 796.7 0.0



FLOODWAY DATA

CHIPPEWA RIVER

1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD 88)FLOODWAYFLOODING SOURCE

1FEET ABOVE MOUTH

TAB

LE 8


SECTIONAREA

(SQUAREFEET)




CHIPPEWA RIVER(CONTINUED)

AX 323,2561 694 15,015 7.1 796.7 796.7 796.7 0.0AY 323,5591 712 13,717 7.7 796.9 796.9 796.9 0.0AZ 323,9361 729 13,341 7.9 797.0 797.0 797.0 0.0BA 324,7961 558 11,571 9.2 797.1 797.1 797.1 0.0BB 327,8961 983 12,397 8.6 799.0 799.0 799.0 0.0BC 336,3171 1,982 20,523 5.2 799.9 799.9 799.9 0.0BD 340,2571 1,757 20,811 5.1 801.3 801.3 801.3 0.0BE 342,6571 1,557 19,602 5.4 801.9 801.9 801.9 0.0BF 345,4571 588 11,949 8.9 802.4 802.4 802.4 0.0BG 346,6571 1,355 19,038 5.6 803.7 803.7 803.7 0.0

CHIPPEWA RIVEROVERFLOW CHANNEL

A 4751 249 2,255 2.5 773.8 773.8 773.8 0.0B 1,0901 347 1,420 4.0 774.3 774.3 774.3 0.0

EAU CLAIRE RIVERA 4202 180 3133 12.3 781.9 773.93 773.9 0.0B 8802 180 3550 10.8 781.9 778.13 778.1 0.0C 1,1902 270 4923 7.8 781.9 780.43 780.4 0.0D 1,5302 215 4366 8.8 781.9 781.33 781.3 0.0E 2,7802 3654 4440 8.6 783.7 783.7 783.7 0.0F 3,8302 205 3523 10.9 784.2 784.2 784.2 0.0G 4,8752 290 4740 8.1 786.5 786.5 786.5 0.0

1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD 88)FLOODWAY

CHIPPEWA RIVER 4SKEWED SECTION (265 FOOT EFFECTIVE FLOW WIDTH)

FLOODING SOURCE

1FEET ABOVE MOUTH 2FEET ABOVE CONFLUENCE WITH CHIPPEWA RIVER 3ELEVATIONS COMPUTED WITHOUT CONSIDERATION OF BACKWATER EFFECTS FROM



FLOODWAY DATA

CHIPPEWA RIVER - CHIPPEWA RIVER OVERFLOW CHANNEL - EAU CLAIRE RIVER

TAB

LE 8

CROSS SECTION DISTANCE1 WIDTH (FEET)

SECTION AREA

(SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY WITHOUT FLOODWAY

WITH FLOODWAY INCREASE

EAU CLAIRE RIVER (CONTINUED)

H 6,260 275 4,715 8.1 787.4 787.4 787.4 0.0I 7,815 360 4,962 7.7 788.4 788.4 788.4 0.0J 8,110 300 5,060 7.6 788.9 788.9 788.9 0.0K 9,890 445 7,236 4.6 790.4 790.4 790.4 0.0L 10,405 315 4,763 6.9 790.5 790.5 790.5 0.0M 12,205 260 4,101 8 791.4 791.4 791.4 0.0

N-O2

P 29,620 1,179 9,583 3.0 810.1 810.1 810.1 0.0Q 30,995 531 5,949 5.0 810.2 810.2 810.2 0.0R 33,442 490 4,853 6.3 811.3 811.3 811.3 0.0S 36,452 427 4,807 5.6 813.0 813.0 813.0 0.0

LOWES CREEKA 1,949 1,437 7,460 0.9 772.6 771.33 771.33 0.0B 2,971 1,310 7,113 0.9 772.6 771.73 771.73 0.0C 3,669 740 1,807 3.3 772.6 771.73 771.73 0.0D 4,433 558 8,481 1.5 777.8 777.8 777.8 0.0E 5,935 311 1,773 4.9 778.4 778.4 778.4 0.0F 6,127 239 1,430 5.3 779.8 779.8 779.8 0.0G 6,461 179 1,849 5.0 781.0 781.0 781.0 0.0H 7,149 431 2,879 2.4 782.5 782.5 782.5 0.0I 8,171 118 961 5.8 784.4 784.4 784.4 0.0J 10,193 415 2,691 2.3 788.3 788.3 788.3 0.0K 11,181 174 1,156 4.8 791.0 791.0 791.0 0.0

1FEET ABOVE CONFLUENCE WITH CHIPPEWA RIVER 2NO FLOODWAY DATA COMPUTED

AND INCORPORATED AREAS

FLOODING SOURCE FLOODWAY 1-PERCENT-ANNUAL-CHANCE FLOODWATER SURFACE ELEVATION (FEET NAVD88)

3ELEVATION COMPUTED WITHOUT BACKWATER EFFECTS FROM CHIPPEWA RIVER

TAB

LE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATAEAU CLAIRE COUNTY, WI

EAU CLAIRE RIVER - LOWES CREEK


SECTION AREA

(SQUARE FEET)




LOWES CREEK(CONTINUED)

L 12,350 186 3,161 3.1 795.5 795.5 795.5 0.0M 13,655 108 852 6.5 797.9 797.9 797.9 0.0N 14,343 495 3,886 1.6 800.6 800.6 800.6 0.0O 14,767 633 4,445 1.3 800.9 800.9 800.9 0.0P 15,126 580 3,175 1.8 801.1 801.1 801.1 0.0Q 16,921 87 700 8 802.5 802.5 802.5 0.0R 17,227 78 690 8.1 804.1 804.1 804.1 0.0S 17,757 407 1,752 3.2 806.2 806.2 806.2 0.0T 17,889 454 1,424 4.1 806.3 806.3 806.3 0.0U 18,178 403 1,521 3.9 807.7 807.7 807.7 0.0V 20,146 802 4,952 1.1 811.1 811.1 811.1 0.0W 22,184 537 3,083 2.1 812.3 812.3 812.3 0.0X 23,854 407 2,903 2.6 815.6 815.6 815.6 0.0Y 24,005 210 2,159 4.0 816.6 816.6 816.6 0.0Z 25,852 476 3,827 1.5 819.9 819.9 819.9 0.0

AA 27,840 108 890 6.3 821.6 821.6 821.6 0.0AB 28,868 606 4,005 1.5 823.8 823.8 823.8 0.0AC 30,783 734 3,718 1.6 826.5 826.5 826.5 0.0AD 31,740 419 2,171 2.6 827.9 827.9 827.9 0.0AE 32,379 175 1,259 4.4 829.2 829.2 829.2 0.0AF 33,740 422 2,264 2.5 831.9 831.9 831.9 0.0AG 34,829 317 1,953 2.9 835.8 835.8 835.8 0.0AH 35,367 94 996 5.6 837.6 837.6 837.6 0.0AI 36,365 327 2,990 1.9 839.1 839.1 839.1 0.0

AND INCORPORATED AREAS


1FEET ABOVE CONFLUENCE WITH CHIPPEWA RIVER

TAB

LE 8


LOWES CREEK


SECTION AREA

(SQUARE FEET)





AJ 37,304 624 5,263 1.1 839.8 839.8 839.8 0.0AK 39,202 552 3,840 1.3 841.0 841.0 841.0 0.0AL 40,183 580 3,280 1.5 841.7 841.7 841.7 0.0AM 42,115 430 3,076 1.8 843.3 843.3 843.3 0.0AN 44,214 510 2,700 1.9 844.9 844.9 844.9 0.0AO 46,350 425 2,969 1.7 847.4 847.4 847.4 0.0AP 48,130 439 3,276 1.6 849.4 849.4 849.4 0.0AQ 49,051 460 2,667 1.9 850.5 850.5 850.5 0.0AR 51,297 566 3,475 1.5 852.9 852.9 852.9 0.0AS 52,287 445 2,946 1.7 854.0 854.0 854.0 0.0AT 54,343 568 4,269 1.2 857.0 857.0 857.0 0.0AU 55,360 496 3,005 1.7 858.1 858.1 858.1 0.0AV 56,316 216 4,298 3.3 860.1 860.1 860.1 0.0AW 56,447 314 5,052 2.0 862.2 862.2 862.2 0.0AX 56,717 481 3,307 1.5 862.5 862.5 862.5 0.0AY 57,790 456 3,481 1.5 863.6 863.6 863.6 0.0AZ 58,760 445 3,227 1.4 864.5 864.5 864.5 0.0BA 60,943 632 3,393 1.3 866.5 866.5 866.5 0.0BB 62,013 556 2,908 1.5 867.6 867.6 867.6 0.0BC 64,015 454 2,607 1.7 870.9 870.9 870.9 0.0BD 66,056 537 3,053 1.5 873.6 873.6 873.6 0.0BE 68,276 681 3,116 1.4 876.8 876.8 876.8 0.0BF 70,485 535 3,011 1.5 879.7 879.7 879.7 0.0BG 72,461 688 2,838 1.6 882.0 882.0 882.0 0.0



TAB

LE 8


LOWES CREEKAND INCORPORATED AREAS


SECTION AREA

(SQUARE FEET)





BH 74,480 482 2,287 1.9 886.2 886.2 886.2 0.0BI 76,243 728 3,392 1.3 889.3 889.3 889.3 0.0BJ 77,670 546 2,862 1.6 890.9 890.9 890.9 0.0BK 78,629 186 2,208 4.6 891.9 891.9 891.9 0.0BL 78,779 216 3,571 3.0 893.8 893.8 893.8 0.0BM 79,470 501 3,433 1.3 894.9 894.9 894.9 0.0BN 80,473 537 3,589 1.2 895.4 895.4 895.4 0.0BO 81,540 617 3,655 1.3 896.3 896.3 896.3 0.0BP 81,949 591 3,514 1.4 896.6 896.6 896.6 0.0BQ 83,597 624 3,308 1.1 897.5 897.5 897.5 0.0BR 85,647 530 2,533 1.5 899.4 899.4 899.4 0.0BS 87,739 421 2,387 1.6 902.7 902.7 902.7 0.0BT 88,922 539 2,391 1.6 904.7 904.7 904.7 0.0BU 91,050 428 2,363 1.6 907.1 907.1 907.1 0.0BV 92,909 639 3,129 1.2 909.4 909.4 909.4 0.0BW 94,780 466 2,645 1.4 912.7 912.7 912.7 0.0BX 97,224 560 3,250 1.2 916.7 916.7 916.7 0.0BY 98,111 211 1,390 3.4 918.6 918.6 918.6 0.0BZ 98,262 230 920 2.8 919.7 919.7 919.7 0.0

SHERMAN CREEKA 2,200 170 690 4.1 784.1 784.1 784.1 0.0B 2,600 219 820 3.4 786.6 786.6 786.6 0.0C 3,900 73 470 6.0 794.7 794.7 794.7 0.0



TAB

LE 8


LOWES CREEK - SHERMAN CREEKAND INCORPORATED AREAS


SECTION AREA

(SQUARE FEET)




SHERMAN CREEK(CONTINUED)

D 5,700 224 952 2.9 806.4 806.4 806.4 0.0E 6,320 296 1,455 1.9 809.0 809.0 809.0 0.0F 8,710 94 391 7.2 819.3 819.3 819.3 0.0G 11,510 128 662 4.2 836.9 836.9 836.9 0.0H 13,027 70 523 5.4 843.0 843.0 843.0 0.0I 16,257 197 1,128 2.4 861.6 861.6 861.6 0.0J 19,240 114 448 6.0 863.9 863.9 863.9 0.0K 23,490 149 608 4.5 881.3 881.3 881.3 0.0L 24,824 456 2,023 1.3 884.6 884.6 884.6 0.0M 26,650 331 1,691 1.5 885.9 885.9 885.9 0.0N 28,220 278 876 2.9 887.2 887.2 887.2 0.0O 29,949 635 1,815 1.4 888.4 888.4 888.4 0.0P 30,775 800 2,078 1.2 888.8 888.8 888.8 0.0Q 31,664 213 2,320 4.4 890.1 890.1 890.1 0.0R 31,932 111 3,640 2.6 892.0 892.0 892.0 0.0S 32,370 306 1,973 1.2 892.1 892.1 892.1 0.0T 32,625 198 1,094 2.0 892.1 892.1 892.1 0.0U 32,763 120 874 2.7 893.7 893.7 893.7 0.0V 33,124 109 1,234 3.4 894.0 894.0 894.0 0.0W 33,441 125 3,547 2.4 894.2 894.2 894.2 0.0X 33,664 209 8,025 1.8 895.8 895.8 895.8 0.0Y 34,231 1,060 13,529 0.6 895.9 895.9 895.9 0.0Z 34,850 1,372 11,157 0.6 895.9 895.9 895.9 0.0

TAB

LE 8


SHERMAN CREEKAND INCORPORATED AREAS




SECTION AREA

(SQUARE FEET)




SHERMAN CREEK(CONTINUED)

AA 35,289 1,532 12,921 0.5 895.9 895.9 895.9 0.0AB 35,840 1,580 15,208 0.4 895.9 895.9 895.9 0.0AC 36,832 955 12,415 1.7 896.0 896.0 896.0 0.0AD 37,363 698 7,790 1.5 896.4 896.4 896.4 0.0



TAB

LE 8


SHERMAN CREEKAND INCORPORATED AREAS

31

5.0 INSURANCE APPLICATIONS

For flood insurance rating purposes, flood insurance zone designations are assigned to a community based on the results of the engineering analyses. The zones are as follows:

Zone A is the flood insurance rate zone that corresponds to the 1-percent annual

chance floodplains that are determined in the FIS by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no ba se flood elevations or depths are shown within this zone.

Zone AE Zone AE is the flood insurance rate zone that corresponds to the 1-percent annual

chance floodplains that are determined in the FIS by detailed methods. I n most instances, whole-foot base flood elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone.

Zone X Zone X is the flood insurance rate zone that corresponds to areas outside the 0.2-

percent floodplain, areas within the 0.2-percent floodplain, and to areas of 1-percent annual chance flooding where average depths are less than 1 foot, areas of 1-percent annual chance flooding where the contributing drainage area is less than 1 square mile, and areas protected from the 1-percent annual chance flood by levees. N o base flood elevations or depths are shown within this zone.

6.0 FLOOD INSURANCE RATE MAP The FIRM is designed for flood insurance and floodplain management applications. For flood insurance applications, the map designates flood insurance rate zones as described

in Section 5.0 and, in the 1-percent annual chance floodplains that were studied by detailed methods, shows selected whole-foot base flood elevations or average depths. I nsurance agents use the zones and base flood elevations in conjunction with information on structures and their contents to assign premium rates for flood insurance policies.

For floodplain management applications, the map shows by tints, screens, and symbols, the

1- and 0.2-percent annual chance floodplains. Floodways and the locations of selected cross sections used in the hydraulic analyses and floodway computations are shown where applicable.

The 2009 countywide FIRM presents flooding information for the entire geographic area of

Eau Claire County. P reviously, separate FHBMs and/or FIRMs were prepared for each identified flood-prone incorporated community of the county. Historical data relating to the maps prepared for each community, up to and including the 2009 c ountywide FIS, are presented in Table 7 "Community Map History."

TA7 – COMMUNITY MAP HISTORY

COMMUNITY NAME

INITIAL IDENTIFICATION

FLOOD HAZARD BOUNDARY MAP REVISIONS DATE

FIRM EFFECTIVE DATE

FIRM REVISION DATE

Altoona, City of

January 9, 1974 June 18, 1976 September 1, 1978

February 18, 2009 None

Augusta, City of

May 10, 1974

April 30, 1976 May 4, 1989 None

Eau Claire County,

(Unincorporated Areas)

January 12, 1973

None

January 12, 1973

July 1, 1974

May 14, 1976 August 16, 1993

Eau Claire, City of

(Dual County Community) (Chippewa County)

September 20, 1974 September 24, 1976 June 1, 1977 January 17, 1985 February 4, 1998

Fairchild, Village of February 18, 2009 None February 18, 2009 None

Fall Creek, Village of

May 24, 1974 September 24, 1976 September 1, 1986 None

TAB

LE 9



COMMUNITY MAP HISTORY

33

7.0 OTHER STUDIES

A FIS has not been prepared for the contiguous community of City of Eau Claire, Chippewa County, Wisconsin. Information pertaining to revised and unrevised flood hazards for each jurisdiction within Eau Claire County has been compiled in this FIS. T herefore, this FIS supersedes all previously printed FIS reports, FIRMs, and or FHBMs for all of the incorporated areas within Eau Claire County.

8.0 LOCATION OF DATA

Information concerning the pertinent data used in preparation of this FIS can be obtained by contacting Federal Insurance and Mitigation Division, FEMA Region V, 536 S outh Clark Street, Sixth Floor, Chicago, Illinois 60605.

9.0 BIBLIOGRAPHY AND REFERENCES

1. Federal Emergency Management Agency, Flood Insurance Study, City of Augusta, Wisconsin, Washington D.C., May 4, 1989.

2. City of Eau Claire, Department of Public Works and Utilities, Engineering Division, City of

Eau Claire. Wisconsin: Flood Plain Study, Scale l"=l00', Contour Interval 2 feet. March 29, 1993.

3. Federal Emergency Management Agency, Federal Insurance Administration, Flood

Insurance Study, Chippewa County, Wisconsin (Unincorporated Areas). Washington, D.C., February 4, 1998.

4. U.S. Department of Housing and Urban Development, Federal Insurance Administration,

Flood Insurance Rate Map, Eau Claire County, Wisconsin (Unincorporated Areas), Washington, D.C., (Flood Insurance Rate Map only), May, 1976.

5. U.S. Department of Agriculture, Soil Conservation Service, Floodplain Management Study,

Lake Eau Claire, Eau Claire County, Wisconsin, April 1984.

6. U.S. Department of Housing and Urban Development, Federal Insurance Administration, Flood Insurance Study, Dunn County, Unincorporated Areas, Wisconsin, October 1981.

7. U.S. Department of Commerce, Bureau of the Census. (2010, 2000) Census of

Population, Number of Inhabitants, Wisconsin, Washington, D.C.

8. U.S. Army Corps of Engineers, St. Paul District, Interim Survey (feasibility) Report for Flood Control, Chippewa River at Eau Claire, Wisconsin, March 1975.

9. U.S. Geological Survey, Water Resources Investigations Report 80-1214, Techniques for

Estimating Magnitude and Frequency of Floods for Wisconsin Streams. D.H. Conger, 1981. 10. U.S. Army Corps of Engineers, St. Paul District, Flood Insurance Study. City of Eau Claire,

Wisconsin, December 1976.DE

34

11. Ayres Associates. Floodway Analysis for the Chippewa River in the Vicinity of the

Proposed Allied Health Center Facility at the University of Wisconsin-Eau Claire, July 1980.

12. Watson, R. Wisconsin Department of Natural Resources. City of Eau Claire Flood

Insurance Study. Letter of Communication to Dr. Brian R. Mrazik, Acting Chief, Federal Emergency Management Agency, July 25, 1983.

13. U.S. Department of the Interior, Geological Survey, Open-File Report, Estimating

Magnitude and Frequency of Floods in Wisconsin. D.H. Conger, 1971. 14. U.S. Department of Agriculture, Soil Conservation Service, Technical Release No. 20.

Computer Program for Project Formulation. Hydrology, 1965. 15. U.S. Geological Survey, 7.5 Minute Series Topographic Maps. Scale 1:24000 Contour

Interval 20 Feet: Augusta West, Contour Interval 10 Feet: Augusta East, 1968; 16. U.S. Department of Transportation, Federal Highway Administration, Report No.

FHWA/RD-86/108, Bridge Waterways Analysis Model: Research Report. J.C. Shearman, W.H. Kirby, V.R. Snyder, and H.N. Flippo, July 1986.

17. U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC-2 Water Surface

Profiles, Computer Program 723-X6-L202A. Davis, California, May 1984.

18. American Materials Corporation, Shoreline Restoration Study. Ayres Associates, 1977.

19. Northern States Power Company, Report on Inspection Dells Hydro. Draft Copy, July 1980.

20. U.S. Army Corps of Engineers, St. Paul District, Flood Plain Information Report. Chippewa River and Duncan Creek, Chippewa Falls, Wisconsin, September 1970.

21. U.S. Army Corps of Engineers, St. Paul District, Flood Plain Information Report. Chippewa

River, Eau Claire, Wisconsin, January 1965.

22. U.S. Department of the Interior, Geological Survey. (Eau Claire East, Wisconsin, 1972; Elk Creek Lake, Wisconsin, 1972; Fall Creek, Wisconsin, 1972; Eau Claire West, Wisconsin, 1972). 7.5-Minute Series Topographic Maps. Scale 1:24,000, Contour Interval 10 Feet.

23. Federal Emergency Management Agency, Flood Insurance Study, City of Eau Claire, Eau

Claire and Chippewa Counties, Wisconsin. Washington, D.C. July 17, 1984 (FIS), January 17, 1985 (FIRM).

24. U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC-RAS River Analysis

System. Davis, California, 2001.

25. Wisconsin Department of Transportation, General Plan for U.S. Highway 53 Bridges Over the Eau Claire River, 1969

35

26. City of Eau Claire. (1974). Topographic Mapping (16 sheets). Scale l"=l00', Contour Interval 2 Feet.

27. U.S. Department of Housing and Urban Development, Federal Insurance Administration. (April 1976). Flood Hazard Boundary Map. City of Augusta, Eau Claire County, Wisconsin.

28. U.S. Department of the Interior, Geological Survey. (1961-1981). Water Resources Data for Wisconsin.

29. U.S. Department of the Interior, Geological Survey. Water Supply Paper No. 1308.

30. Wisconsin Department of Natural Resources. (2004). Wisconsin’s Floodplain Management Program. Chapter NR 116, Register No. 584.

31. Wisconsin Legislative Reference Bureau. (2005). State of Wisconsin 2005 - 2006 Blue Book.

32. Federal Emergency Management Agency, Federal Insurance Administration, Flood Insurance Study, Dunn County, Wisconsin (Unincorporated Areas). Washington, D.C., August 16, 1996.

33. U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC-HMS Hydrologic Modeling System, version 3.5, August 2010.

34. U.S. Geological Survey. J.F. Walker & W.R.Krug, (2003). Water Resources Investigations Report 03-4250, Techniques for Estimating Magnitude and Frequency of Floods for Wisconsin Streams

35. City of Eau Claire, Wisconsin; 2007-06 Aerial Photography and 2-FT Topographic Mapping including Digital Terrain Model (DTM) data. June 1, 2007.

36. U.S. Army Corps of Engineers, Hydrologic Engineering Center. (2010). HEC-RAS River Analysis System, Version 4.1.0 Davis, California.

37. U.S. Department of Commerce. (1963). Technical Paper 40, Rainfall Frequency Atlas of the United States.

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U.S.

HIG

HWA Y

312 M

ENAR

DS R

OAD

R AIL

ROA D

10T H

STR

E ET

CITY

OF

EAU

CLAI

R E

EAU

CLAI

RE C

OUNT

Y

LEGEND0.2% ANNUAL CHANCE FLOOD1% ANNUAL CHANCE FLOOD2% ANNUAL CHANCE FLOOD

10% ANNUAL CHANCE FLOODSTREAM BED


4% PROFILE NOT AVAILABLE BELOW THIS POINT

EAU

CLAI

RE C

OUNT

Y

CHIP

PEW

A CO

UNTY

CULVERT

CULVERT

CULVERT

CULVERT


eau claire county, wisconsin - starr team · eau claire county, wisconsin, and incorporated areas ....

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