PUBLIC NOTICE REQUEST FOR PERMISSION TO MODIFY A U.S. ARMY CORPS OF ENGINEERS PROJECT UNDER SECTION 408

Transcription

1 DEPARTMENT OF THE ARMY ROCK ISLAND DISTRICT CORPS OF ENGINEERS CLOCK TOWER BUILDING - PO BOX 2004 ROCK ISLAND, ILLINOIS Emergency Management Division PUBLIC NOTICE REQUEST FOR PERMISSION TO MODIFY A U.S. ARMY CORPS OF ENGINEERS PROJECT UNDER SECTION 408 TITLE: Green Bay Levee Height Alteration, at the Green Bay Drainage and Levee District No. 2, Lee County, Iowa. (Public Notice ID #2018-MM6) PUBLIC NOTICE COMMENT PERIOD: Begins: October 24, 2018 Expires: November 30, 2018 Interested parties are hereby notified that the US Army Corps of Engineers, Rock Island District (District), received a Department of the Army Section 408 permission application for work at or near a federally authorized flood risk management project of the United States, as described below and shown on attached figures. The District is soliciting comments from anyone having an interest in the requested levee alteration. Comments will become part of the District s administrative record and will be considered in determining whether to approve the requested alteration. Comments supporting, opposing, or identifying concerns are all welcome. Comments providing substantive information or a rationale for the commenter s position are the most helpful. This public notice is not a paid advertisement and is for public information only. Issuance of this notice does not imply District endorsement of the project as described. REQUESTER: In compliance with 33 USC 408 (Section 14 of the Rivers and Harbors Act of 1899; hereinafter Section 408), the Green Bay Levee & Drainage District No. 2, requested permission to retain the existing unapproved height increase and further increase the height of the federally-authorized locally owned and operated flood risk management project/levee. LOCATION: Green Bay Levee & Drainage District No. 2. (Green Bay) is located between the confluences of the Skunk River and Mississippi River at River Mile (RM) 395.9, and Lost Creek and the Mississippi River at RM in Lee County, Iowa (Figure 1). A portion of the unincorporated community of Wever, IA is located within the district. The leveed area is largely agricultural and residential development, but also includes the recently constructed Iowa Fertilizer Plant. The Flood Risk Management Project (FRMP) is located between Lock and Dam 18 and Lock and Dam 19 on the Mississippi River (Figure 2).

2 Other federally authorized locally owned and operated flood risk management systems upstream of Lock and Dam 19 (Figures 1 and 2): Two Rivers Levee & Drainage District Lower Unit Located on the right descending bank from Lock & Dam 20 at RM to approximately RM Henderson County Drainage District No. 1&2 Located on the left descending bank from Lock and Dam 20 at RM to Ellison Diversion Ditch at approximately RM Burlington North Bottoms Levee Located at the confluence of the Flint Creek and the Mississippi River at RM to approximately RM Other non-federally authorized locally operated and maintained flood risk management systems within pool 19 include (Figures 1 and 2): Niota Drainage and Levee District Located on the left descending bank from RM to Union Township Drainage and Levee District Located on the left descending bank of the Skunk River near the confluence with Mississippi River. Cities within Pool 19 include: Burlington, Iowa Gulf Port, Illinois Shokokon, Illinois Carman, Illinois Lomax, Illinois Dallas City, Illinois Pontoosuc, Illinois Niota, Illinois Fort Madison, Iowa Montrose, Iowa Nauvoo, Illinois Sandusky, Iowa Hamilton, Illinois Keokuk, Iowa Wever, Iowa West Burlington, Iowa REQUESTER S PROPOSED ACTION: The existing flood risk management project of Green Bay Levee & Drainage District No. 2 consists of earthen embankment main stem and tie-back levees, natural high ground, and interior drainage features such as drainage ditches, ponding areas, and pump stations. Green Bay proposes to increase the height of their levee in order to meet, at minimum, the FEMA accreditation requirements. This will include work along the mainstem Mississippi River Levee and tieback levees along the Skunk River and Lost Creek. Levees along the Skunk River and Lost Creek may need to be extended in order to tie into high ground. The federally authorized levee elevation is approximately at the 1% Annual Chance Exceedance (ACE) flood event plus 1 foot (approximately 100 year + 1 foot). Green Bay 2

3 raised the levee to approximately 2 feet higher than the federally authorized elevation, and is currently above the.2% ACE (100 year + 3 feet) elevation. The newly proposed levee elevation would be approximately three (3) feet higher than the authorized elevation (.2% ACE (approximately 100 year + 4 feet event). At a minimum, Green Bay would like to retain the existing elevation profile (.2% ACE (100 year + 3 feet). (See Figure 3, 4, and 5 for proposed levee profiles along the Skunk River, Mississippi River, and Lost Creek). Final levee dimensions (width), material, and borrow locations would be determined upon completion of final design by the applicant. Typical levee improvements would include compacted earthen fill placed on top and on the landside levee slopes. The applicant would determine the final dimensions upon final design and will be required to follow and comply with the National Environmental Policy Act (NEPA) process. PURPOSE AND NEED: The Green Bay Levee and Drainage District No. 2 identified the purpose of the project is to manage flood risk within the leveed area and reduce flood operation and maintenance cost to Green Bay. The following information was provided by Green Bay, as submitted in the 22 August 2018 Green Bay Levee & Drainage District #2 Model Submittal report (August Report), and summarized for this public notice: (Please note the data below has not been independently verified by the Rock Island District) Since the flood of 1993, when the levee was overtopped, Green Bay has experienced four flood events in which they constructed emergency measures to raise their levee. The most serious flooding was in 2008 when the water levels were above the 1993 measurements and reached record levels. At that time a major push-up was required to prevent the overtopping of the main stem system. After the event, major levee repairs cost over $1.7 million of local and Federal money to complete. Within the leveed area there are thirty-four (34) homesteads, thirteen (13) farmsteads and operations consisting of 15,138 acres of prime farmland including livestock numbering in the thousands. The combined value of these personal assets is over $134 million with a potential loss of $17 million in growing crops, stored grain and livestock in the event of a levee overtopping. Green Bay also protects a local grain Cooperative river terminal. This facility has twelve full time employees and an at-risk property value of $4.5 million, and at times throughout the year has corn and soybeans stored at a value of $21 million. This river terminal services farmers and grain elevators in the four (4) surrounding counties in Southeast Iowa. Also, located within Green Bay s boundary of protection is the Iowa Fertilizer Company. The facility has a total investment of over $3.2 billion, and the plant employs 221 local people. Flooding at or above the 1993 and 2008 water surface elevations may cause a plant shutdown due to the loss of access via roads located within the leveed area. Depending upon the time of flooding, a plant closure could affect the agricultural nitrogen production and distribution throughout the Midwest. This plant is currently servicing a 400 mile radius that incorporates portions of Iowa, Illinois, and Missouri. It also is a major producer of Diesel Exhaust Fluid (DEF) for the central part of the United States. Diesel Exhaust Fluid is a product used in diesel engines throughout the country for cleaner exhaust emissions. In summary, at any given time Green Bay protects seventy-three (73) adult residents plus an unknown number of children, 233 full time jobs, $3.3 billion of fixed assets and equipment, $38 million of perishable inventory, and $17 million estimated loss of business per week of operation. 3

4 CHANGES IN WATER SURFACE PROFILE: In accordance with EC the applicant completed a hydraulic system performance analysis. The changes in levee heights may permanently alter water surface profiles for flood events between approximately the 0.5% Annual Chance Exceedance (ACE) (200-year) flood event and greater than the 0.2% ACE (500-year) flood event. Changes in water surface elevation at or below the 1% ACE (100- year) event are not anticipated based on the completed hydraulic modeling. Attached to this public notice are a series of figures depicting the maximum water surface impact between the authorized levee elevations and the proposed top of levee elevations. The impact, or difference, is calculated by determining the river flow that would just overtop the proposed top of levee. This flow is then simulated in a computer-generated hydraulic model to determine the water surface profile (water surface elevations along the river) based on the proposed levee condition. The process is repeated using the same flow used in the proposed condition scenario but with the authorized top of levee elevations to generate a new water surface profile. The hydraulic impacts or differences are calculated by subtracting the model results for the authorized levee condition from the proposed levee condition. A positive number means the water surface will be higher with the proposed levee in place. The following information was provided by the Levee and Drainage District #2 as submitted in the 22 August 2018 Green Bay Levee & Drainage District #2 Model Submittal report (August Report) and summarized for this public notice: (Please note that the data below has not been independently verified by the Rock Island District) In Carman, Illinois some houses and buildings that would have otherwise been free from water at ground level could receive water with this project during the worst case modeled flood event. The potential changed conditions may affect, seven (7) houses, four (4) detached garages and/or sheds, twelve (12) additional properties would have the potential for additional flooding in their yards when compared to the federally-authorized condition. The proposed Green Bay levee alteration could also inundate Illinois Route 522 (Carman Rd.) near Carman, Illinois, U.S. Highway 34 near Gulfport, Illinois, and/or U.S. Highway 61 near the Skunk River, Iowa. At Illinois 522 and U.S. 34, the highways are inundated for events at or above the 0.2% ACE (500-year). These roads would need to be closed due to overtopping prior to reaching the elevation of the proposed Green Bay levee improvements. Additional water has the potential to cover the inundated sections of Carman Road and U.S. Highway 34 due to the potential increase in water surface elevations. U.S. Highway 61 does not appear to overtop for any of the modeled events. There are also structures that would be inundated during a flood event with the federallyauthorized Green Bay levee height increase. These primarily occurred at Carman, Shokokon, Lomax, Dallas City, near Wever, and Burlington. These already inundated structures will receive an additional amount of water depending on the increase in water surface elevations for the specific event at their location. Also, the sections of highway that would already be inundated by the authorized condition may also receive additional depth of water. (See Inundation and Water Depth Maps) LOCATION MAP(S)/DRAWING(S): See maps below for locations and changes in inundation. 4

5 REGULATORY AUTHORITY: The District will review the alteration request according to the provisions of Section 14 of the Rivers and Harbors Act of 1899 (33 U.S.C. 408). The Green Bay Levee and Drainage District No. 2 has the responsibility to acquire all other permissions or authorizations required by federal, state, and local laws or regulations, including any required permits from the US Army Corps of Engineer s Regulatory Program under Section 10 of the Rivers and Harbors Act of 1899 (33 USC 403), Section 404 of the Clean Water Act (33 USC Section 1344) and/or Section 103 of the Marine Protection, Research and Sanctuaries Act of 1972 (33 USC 1413). The compliance determination for any Section 10/404/103 permit decision associated with the proposed alteration is separate from and will not be included in the Section 408 compliance determination. An approval under Section 408 does not grant any property rights or exclusive privileges nor does it authorize any injury to the property or rights of others. EVALUATION: Engineering Circular (EC) outlines several factors the District uses to decide whether to grant the requested permission for project modification under Section 408. The decision will reflect the national concern for both protection and utilization of important resources. The benefit which reasonably may be expected to accrue from the proposal must be balanced against its reasonably foreseeable detriments. Review of the requests for modification will be reviewed by the District technical review team using the following factors: 1. Impair the Usefulness of the Project Determination. The review team will determine if the proposed alteration would limit the ability of the federally authorized project to function as authorized, or would compromise or change any authorized project conditions, purposes or outputs. The decision whether to approve a request for modification would be based on a determination of no impairments. 2. Injurious to the Public Interest Determination. The review team will review the proposed alterations to determine the probable impacts, including cumulative impacts, on the public interest. The team s evaluation of the proposed alteration s probable impacts to the federally-authorized project may have on the public interest requires a careful weighing of all those factors relevant in each particular case. Factors relevant to the public interest depend upon the type of Federally-authorized project being altered and may include, but are not limited to, such things as conservation, economic development, historic properties, cultural resources, environmental impacts, water supply, water quality, flood hazards, floodplains, residual risk, induced damages, navigation, shore erosion or accretion, and recreation. The decision whether to approve an alteration will be determined by the consideration of whether benefits are commensurate with risks. If the potential detriments are found to outweigh the potential benefits, the District may determine the proposed alteration is injurious to the public interest. 3. Environmental Compliance. A decision on a Section 408 request is a federal action, and therefore subject to the NEPA and other environmental compliance requirements, including the National Historic Preservation Act, and Endangered Species Act. While the District ensures environmental compliance, the requester is providing all information the District identifies as necessary to satisfy all applicable federal laws, executive orders, regulations, policies, and ordinances. 5

6 Based on information provided by the applicant to date, the District will require the Green Bay Levee and Drainage District No. 2 to prepare an environmental assessment (EA) addressing local and Mississippi River system wide impacts. The Green Bay Levee and Drainage District No. 2 would prepare the EA documentation prior to alteration of the Green Bay Flood Risk Management Project. 4. Technical Analysis. The District is working closely with the requestor to ensure all required technical plans, maps, drawings, and specifications are provided and complete. A District-led Agency Technical Review (ATR) team is determining any potential adverse impacts to the District-authorized flood protection system. SOLICITATION OF COMMENTS: The District is soliciting comments from the public; Federal, state, and local agencies and officials; Indian Tribes; and other interested parties in order to consider and evaluate the impacts of the proposed activity. The District will consider any comments received to determine whether to issue, modify, condition or deny a permission for this proposal. To make this decision, the District will assess impacts on endangered species, historic properties, water quality, general environmental effects, and other public interest factors listed above. The District will use the comments to determine the need for a public hearing and to determine the overall public interest of the proposed activity. The materials submitted as part of the Section 408 request become part of the public record and are thus available to the general public under the procedures of the Freedom of Information Act (FOIA). Individuals may submit a written request to obtain materials under FOIA or make an appointment to view the project file at the Rock Island District Corps of Engineers, Office of Counsel, Rock Island Arsenal, Rock Island, Illinois. The District presumes all parties receiving this notice will wish to respond to this public notice; therefore, a lack of response will be interpreted as meaning there is no objection to the project as described. COMMENT SUBMISSION AND ADDITIONAL INFORMATION: Written comments on the described work should reference the Public Notice number found in the Title heading near the top of this notice. Comments must reach this office no later than the above expiration date of the Public Notice to become part of the record and be considered in the decision. Comments or requests for additional information should be mailed or ed to the following address: MVR408@usace.army.mil U.S. Army Corps of Engineers Emergency Operations Clock Tower Building P.O. Box 2004 Rock Island, Illinois ATTN: Paul St. Louis 6

7 Figure 1 - Mississippi River Pool 19 Overview Lock & Dam 18 Iowa Missouri Illinois Two Rivers Levee & Drainage District Lower Unit Burlington North Bottoms Levee Henderson County Drainage District No. 1 Henderson County Drainage District No. 2 Union Township East Union Township West Green Bay Levee & Drainage District No. 2 Niota Drainage & Levee District Lock & Dam Miles Esri, HERE, DeLorme, MapmyIndia, OpenStreetMap contributors, and the GIS user community, Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

8 Figure 2 - Green Bay Levee & Drainage District No. 2 Overview U.S. HWY 61 RM Iowa Fertilizer Plant RM Pump Station New_Shapefile Union Township East Union Township West Green Bay Levee & Drainage District No. 2 Niota Drainage & Levee District Miles Esri, HERE, DeLorme, MapmyIndia, OpenStreetMap contributors, and the GIS user community, Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

9 537 Corps of Engineers Plot of Green Bay Submitted Profiiles Levee Profile with SUBMITTED Proposed (100 yr + 4 ft) Green Bay Geometry (ft) 536 Levee Profile with USACE Authorized Green Bay Geometry (ft) Levee Profile with SUBMITTED Existing Green Bay Geometry (ft) 2007 NLD (ft) 535 Levee Profile with USACE Existing Green Bay Geometry based on 2016 NLD (ft) 1% (100yr) Water Surface Profile Elevation MSL Mississippi River River Mile

10 560 Corps of Engineers Plot of Green Bay Submitted Profiles Levee Profile along Skunk River with SUBMITTED Proposed (100 yr + 4 ft) Green Bay Geometry (ft) Levee Profile along Skunk River with USACE Authorized Green Bay Geometry (ft) 1% (100yr) Water Surface Profile Elevation MSL Skunk River River Mile

11 555 Corps of Engineers Plot of Green Bay Submitted Profiles Levee Profile along Lost Creek with SUBMITTED Proposed (100 yr + 4 ft) Green Bay Geometry (ft) Levee Profile along Lost Creek with USACE Authorized Green Bay Geometry (ft) 1% (100yr) Water Surface Profile Elevation MSL Lost Creek River Mile

12 Maximum Potential for Change in Water Surface Profiles Maximum Potential for Change in Water Surface Profiles After Improving Green Bay Levee & Drainage District #2 Elevations from Authorized Conditions (1954) to Proposed Condition (2018)* Two Rivers Levee & Drainage District Lower Unit Henderson County Drainage District 1& Green Bay Levee & Drainage District # Iowa Illinois Missouri *Flood fighting efforts during 1993 and 2008 flood events exceeded the Proposed Condition in most locations. Feet 0 15,000 30,000 60,000 Esri, HERE, DeLorme, MapmyIndia, OpenStreetMap contributors, and the GIS user community, Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

13 Estimated Potential for Change in Water Surface Profiles Estimated Potential for Change in Water Surface Profiles After Improving Green Bay Levee & Drainage District #2 Elevations from As-Built (1963) to Proposed Condition (2018)* - Approximate 2008 Profiles Two Rivers Levee & Drainage District Lower Unit Henderson County Drainage District 1& Green Bay Levee & Drainage District # Iowa Illinois Missouri *Flood fighting efforts during 1993 and 2008 flood events exceeded the Proposed Condition in most locations. Feet 0 15,000 30,000 60,000 Esri, HERE, DeLorme, MapmyIndia, OpenStreetMap contributors, and the GIS user community, Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

14 Two Rivers Levee & DD Lower Inundation Comparison For an event over the 500 year flood event North Section (Sheet 1 of 2) Drainage District Boundary Proposed 100 Year + 4' Levee ,500 3,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

15 Two Rivers Levee & DD Lower Inundation Comparison For an event over the 500 year flood event South Section (Sheet 2 of 2) Drainage District Boundary Proposed 100 Year + 4' Levee ,500 3,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

16 Henderson Districts 1 & 2 Inundation Comparison For an event over the 500 year flood event Drainage District Boundary Proposed 100 Year + 4' Levee 0 2,500 5,000 10,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

17 Burlington Industrial Levee Inundation Comparison For an event over the 500 year flood event Drainage District Boundary Proposed 100 Year + 4' Levee ,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

18 Burlington Inundation Comparison For an event over the 500 year flood event Proposed 100 Year + 4' Levee ,500 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

19 Shokokon Inundation Comparison For an event over the 500 year flood event Proposed 100 Year + 4' Levee ,020 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

20 Carman Inundation Comparison For an event over the 500 year flood event (Modeled Event Comparable to 1993 Flood x 1.2) Proposed 100 Year + 4' Levee Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

21 Carman Inundation Comparison For an event over the 500 year flood event 0 Proposed 100 Year + 4' Levee ,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

22 Lomax Inundation Comparison For an event over the 500 year flood event 0 Proposed 100 Year + 4' Levee 500 1,000 2,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

23 Union Township West Inundation Comparison For an event over the 500 year flood event 0 Drainage District Boundary Proposed 100 year + 4' Levee 500 1,000 2,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

24 Union Township East Inundation Comparison For an event over the 500 year event Drainage District Boundary Proposed 100 year + 4' Levee ,000 2,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

25 Green Bay Levee & DD No. 2 Inundation Comparison For an event over the 500 year event Drainage District Boundary Proposed 100 year + 4' Levee 0 3,750 7,500 15,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

26 Dallas City Inundation Comparison For an event over the 500 year flood event East Section (Sheet 2 of 2) Proposed 100 Year + 4' Levee ,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

27 Dallas City Inundation Comparison For an event over the 500 year flood event West Section (Sheet 1 of 2) 0 Proposed 100 Year + 4' Levee ,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

28 Pontoosuc Inundation Comparison For an event over the 500 year flood event West Section (Sheet 1 of 2) Proposed 100 Year + 4' Levee ,000 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

29 Niota Levee & Drainage District Inundation Comparison For an event over the 500 year flood event Drainage District Boundary Proposed 100 Year + 4' Levee ,200 2,400 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

30 Fort Madison Inundation Camparison For an event over the 500 year flood event East End (Page 2 of 2) Proposed 100 Year + 4' Levee ,200 2,400 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community

31 Fort Madison Inundation Comparison For an approximate 500 year flood event West End (Page 1 of 2) Proposed 100 Year + 4' Levee ,200 2,400 Feet Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community