CITY OF PORTLAND, OREGON MULTNOMAH, CLACKAMAS, AND WASHINGTON COUNTIES REVISED: NOVEMBER 26, 2010 Federal Emergency Management Agency Flood Insurance Study Number 410183V000B
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 may not contain all data available within the repository. It is advisable to contact the community repository located at 1221 SW 4 th Avenue, Room 230, Portland, OR 97204, for any additional data. As part of these studies, the format of the map panels changed. Previously, flood hazard information was shown on both the Flood Insurance Rate Map and Flood Boundary and Floodway Map. In the new format, all Base Flood Elevations, cross sections, zone designations, and floodplain and floodway boundary delineations are shown on the Flood Insurance Rate Map, and the Flood Boundary and Floodway Map has been eliminated. Some flood insurance zone designations were changed to reflect the new format. Areas previously shown as Zones A1-A30 were changed to Zone X (unshaded). In addition, all zone designations and reach determinations were removed from the profile panels in the Flood Insurance Study report. Part of all of this FIS may be revised and republished at any time. In addition, part of this FIS may be revised by a Letter of Map Revision process, which does not involve republication or redistribution of the FIS. It is, therefore, the responsibility of the user to consult with community officials and to check the community repository to obtain the most current FIS report components. This FIS report was revised on November 26, 2010. Users should refer to Section 10.0, Revisions Descriptions, for further information. Section 10.0 is intended to present the most up-to-date information for specific portions of this FIS report. Therefore, users of this FIS report should be aware that the information presented in Section 10.0 supercedes information in Sections 1.0 through 9.0 of this FIS report.
10.0 REVISIONS DESCRIPTIONS...35 10.1 First Revision...35
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Flooding Source and Location Table 2. Summary of Elevations 10-Percent-Annual- Chance Elevation (Feet NAVD) 2-Percent-Annual- Chance 1-Percent-Annual- Chance 0.2-Percent-Annual- Chance Columbia River At Vancouver, Washington (RM 106.5) 25.8 29.9 31.6 35.2 Force Lake In vicinity of North Victory Boulevard & North Force Avenue --1 --1 14.0 --1 Internal Drainage - NE 33rd Basin North of NE Elrod Road approximately between NE 33rd Drive and NE Airport Perimeter Drive --1 --1 17.0 --1 Approximately 150 feet east of Peninsula Drainage Canal --1 --1 15.0 --1 Approximately 550 feet North of NE Elrod Drive 350 feet West of NE 33rd Drive --1 --1 15.0 --1 Approximately 270 feet South East of the intersection between NE Elrod Road and NE 33rd Drive --1 --1 15.0 --1 South of NE Elrod Road approximately between NE 33rd Drive and NE Airport Perimeter Drive --1 --1 13.0 --1 Peninsula Drainage District No. 1 In vicinity of North Force Avenue & North Broadacre Street --1 --1 14.0 --1 Willamette River At Morrison Bridge (RM 12.8) 25.5 30.2 32.3 37.2 --1 Data Not Available 11
FLOODING SOURCE CROSS SECTION DISTANCE 1 COLUMBIA RIVER A B C D E F G H I J K FLOODWAY 1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION SECTION MEAN WITHOUT WITH WIDTH 4 REGULATORY 2 AREA VELOCITY FLOODWAY 3 FLOODWAY 3 INCREASE (FEET) (SQ.FEET) (FEET/SEC.) (FEET NAVD) (FEET NAVD) (FEET NAVD) (FEET) 102.17 3,233 / 321 222,371 2.5 30.4 31.1 31.7 0.6 104.43 3,630 / 204 184,160 3.1 31.0 31.3 32.0 0.7 105.63 3,423 / 2,166 5 164,083 3.4 31.4 31.5 32.5 1.0 106.42 3,285 / 2,153 5 147,137 3.8 31.6 31.6 32.6 1.0 107.39 4,594 / 3,481 5 189,801 3.0 31.9 31.9 32.9 1.0 109.49 4,360 / 3,177 204,990 2.8 32.3 32.1 33.1 1.0 110.17 4,000 / 3,080 161,601 3.5 32.4 32.2 33.1 0.9 111.15 4,619 / 1,847 185,625 3.0 32.7 32.4 33.3 0.9 112.93 7,245 / 1,661 191,008 3.0 33.0 32.7 33.6 0.9 115.02 4,292 / 1,322 161,790 3.5 33.6 33.2 34.1 0.9 116.10 4,773 / 883 178,406 3.2 33.9 33.4 34.3 0.9 1 Miles Above Mouth 2 Elevations based on combined stage-frequency curve 3 Elevations based on HEC-2 Model calibrated to approximate 100-year combined-stage frequency curve 4 Width/width within City of Portland 5 Width does not include island TABLE 4 FEDERAL EMERGENCY MANAGEMENT AGENCY CITY OF PORTLAND, OR (MULTNOMAH, CLACKAMAS, AND WASHINGTON COS.) FLOODWAY DATA COLUMBIA RIVER
(MULTNOMAH, CLACKAMAS, AND WASHINGTON COS.)
FLOODING SOURCE CROSS SECTION DISTANCE 1 JOHNSON CREEK A B C D E F G H I J K L M N O P Q R S T U V W X Y Z FLOODWAY 1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION SECTION MEAN WITHOUT WITH WIDTH REGULATORY INCREASE AREA VELOCITY FLOODWAY FLOODWAY (FEET) (SQ.FEET) (FEET/SEC.) (FEET NAVD) (FEET NAVD) (FEET NAVD) (FEET) 1.187 73 924 9.1 49.0 49.0 49.3 0.3 1.284 107 1,574 5.0 50.7 50.7 51.0 0.3 1.426 67 588 10.0 52.1 52.1 52.9 0.8 1.514 100 414 7.8 57.7 57.7 57.7 0.0 1.574 152 799 2.7 60.0 60.0 60.0 0.0 1.646 88 609 4.8 60.4 60.4 60.4 0.0 1.715 122 256 5.2 60.9 60.9 60.9 0.0 1.988 50 1,021 8.7 70.0 70.0 70.2 0.2 2.097 65 523 6.8 71.8 71.8 71.9 0.1 2.225 51 549 9.4 73.8 73.8 74.0 0.2 2.310 52 644 7.6 75.9 75.9 76.1 0.2 2.385 37 285 9.9 76.9 76.9 77.3 0.4 2.498 40 348 8.1 82.4 82.4 82.8 0.4 2.628 94 429 6.6 84.3 84.3 85.0 0.7 2.680 80 510 5.5 87.1 87.1 87.2 0.1 2.836 52 333 8.5 91.0 91.0 91.5 0.5 3.022 40 1,033 94 9.4 96.4 96.4 97.1 07 0.7 3.139 43 1,351 6.6 106.3 106.3 106.9 0.6 5.616 48 416 7.1 194.0 194.0 194.7 0.7 5.730 40 643 4.8 195.0 195.0 196.0 1.0 5.826 39 219 13.5 195.7 195.7 195.7 0.0 5.922 191 855 3.5 199.4 199.4 199.4 0.0 5.982 50 564 5.3 199.4 199.4 199.4 0.0 6.256 50 928 3.2 202.3 202.3 202.7 0.4 6.361 70 1,263 2.4 202.3 202.3 203.2 0.9 6.552 60 709 4.2 202.8 202.8 203.8 1.0 1 Miles Above Mouth TABLE 4 FEDERAL EMERGENCY MANAGEMENT AGENCY CITY OF PORTLAND, OR (MULTNOMAH, CLACKAMAS, AND WASHINGTON COS.) FLOODWAY DATA JOHNSON CREEK
FLOODING SOURCE CROSS SECTION DISTANCE 1 JOHNSON CREEK (cont.) BA BB BC BD BE BF WIDTH 2 FLOODWAY 1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION SECTION MEAN WITHOUT WITH REGULATORY AREA VELOCITY FLOODWAY FLOODWAY INCREASE (FEET) (SQ.FEET) (FEET/SEC.) (FEET NAVD) (FEET NAVD) (FEET NAVD) (FEET) 11.614 129 / 129 718 3.6 249.9 249.9 250.5 0.6 11.733 130 / 88 694 3.7 250.3 250.3 251.2 0.9 11.823 129 / 61 819 3.1 250.9 250.9 251.8 0.9 11.928 155 / 0 3 710 3.6 251.8 251.8 252.6 0.8 11.969 57 / 1 543 4.7 254.2 254.2 255.1 0.9 12.099 79 / 6 808 3.1 255.3 255.3 255.9 0.6 1 Miles Above Mouth 2 Width/width within City of Portland 3 Entire width outside City of Portland TABLE 4 FEDERAL EMERGENCY MANAGEMENT AGENCY CITY OF PORTLAND, OR (MULTNOMAH, CLACKAMAS, AND WASHINGTON COS.) FLOODWAY DATA JOHNSON CREEK
FLOODING SOURCE CROSS SECTION DISTANCE 1 WILLAMETTE RIVER A B C D E F G H I J K L M N O P Q R S T U V W X Y Z WIDTH FLOODWAY 1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION SECTION MEAN WITHOUT WITH REGULATORY AREA VELOCITY FLOODWAY 2 FLOODWAY 2 INCREASE (FEET) (SQ.FEET) (FEET/SEC.) (FEET NAVD) (FEET NAVD) (FEET NAVD) (FEET) 0.38 1,600 / 846 4 85,130 3.1 30.8 29.4 30.2 0.8 1.52 1,700 / 756 4 113,090 2.3 30.9 29.5 30.3 0.8 3.03 2,073 / 1,273 4 110,545 2.4 30.9 29.6 30.4 0.8 3.50 1,896 110,822 3.4 30.9 29.6 30.4 0.8 4.54 1,710 116,277 3.2 31.0 29.7 30.5 0.8 5.00 1,716 103,773 3.6 31.2 29.7 30.5 0.8 6.00 1,420 85,079 4.4 31.2 29.8 30.6 0.8 6.70 1,417 80,505 4.7 31.2 29.9 30.7 0.8 7.00 1,440 82,091 4.5 31.3 30.0 30.8 0.8 7.68 1,870 123,102 3.0 31.4 30.3 31.1 0.8 8.40 2,045 122,118 3.1 31.4 30.4 31.2 0.8 9.66 1,697 98,255 3.8 31.5 30.5 31.2 0.7 11.00 1,023 68,973 5.4 31.6 30.6 31.4 0.8 11.72 928 54,397 6.9 31.7 30.6 31.4 0.8 11.94 740 53,452 7.0 31.7 30.8 31.5 0.7 12.30 1,144 70,636 5.3 32.0 31.3 32.1 0.8 12.62 849 60,729 6.2 32.1 31.3 32.1 0.8 12.99 1,197 67,540 5.6 32.3 31.7 32.4 0.7 13.16 1,295 69,242 5.4 32.4 31.8 32.5 0.7 13.33 1,378 66,329 5.7 32.4 31.8 32.6 0.8 13.51 1,339 69,350 5.4 32.5 31.9 32.7 0.8 13.73 1,339 69,350 5.4 32.6 32.0 32.7 0.7 13.84 1,371 73,934 5.1 32.7 32.1 32.9 0.8 14.00 1,585 73,405 5.1 32.7 32.2 32.9 0.7 14.90 1,611 3 68,291 5.5 33.1 32.7 33.2 0.5 15.66 2,948 3 122,470 3.1 33.3 33.0 33.9 0.9 1 Miles Above Mouth 2 Elevations computed without consideration of influence from Columbia River 3 Width does not include island 4 Width/width within City of Portland TABLE 4 FEDERAL EMERGENCY MANAGEMENT AGENCY CITY OF PORTLAND, OR (MULTNOMAH, CLACKAMAS, AND WASHINGTON COS.) FLOODWAY DATA WILLAMETTE RIVER
FLOODING SOURCE CROSS SECTION DISTANCE 1 WILLAMETTE RIVER (cont'd) AA AB AC AD WIDTH FLOODWAY 1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION SECTION MEAN WITHOUT WITH REGULATORY AREA VELOCITY FLOODWAY 2 FLOODWAY 2 INCREASE (FEET) (SQ.FEET) (FEET/SEC.) (FEET NAVD) (FEET NAVD) (FEET NAVD) (FEET) 16.01 1,385 59,269 6.33 33.5 33.0 33.9 0.9 16.33 1,405 69,924 5.36 33.6 33.4 34.3 0.9 16.62 1,165 54,209 6.92 33.9 33.6 34.5 0.9 16.74 1,415 74,793 5.01 34.2 34.2 35.1 0.9 1 Miles Above Mouth 2 Elevations computed without consideration of influence from Columbia River TABLE 4 FEDERAL EMERGENCY MANAGEMENT AGENCY CITY OF PORTLAND, OR (MULTNOMAH, CLACKAMAS, AND WASHINGTON COS.) FLOODWAY DATA WILLAMETTE RIVER
The area between the floodway and 100-year floodplain boundaries is termed the floodway fringe. The floodway fringe encompasses the portion of the floodplain that could be completely obstructed without increasing the WSEL of the 100-year flood more than 1 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 1. Figure 1. Floodway Schematic 5.0 INSURANCE APPLICATION For flood insurance rating purposes, flood insurance zone designations are assigned to a community based on the results of the engineering analyses. These zones are as follows: Zone A Zone A is the flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the FIS by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no BFEs or depths are shown within this zone. Zone AE Zone AE is the flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the FIS by detailed methods. Whole-foot BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Zone AH Zone AH is the flood insurance rate zone that corresponds to the areas of 100-year shallow flooding (usually areas of ponding) where average depths are between 1 and 3 feet. Whole-foot BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. 29
41. http://www.census.gov 42. U.S. Department of the Army, Corps of Engineers, Portland District, Johnson Creek, Flooded Area Update, December 1999. 43. U.S. Department of the Army, Corps of Engineers, Portland District, Crystal Springs Creek, Flooded Area Update, March 2001. 44. U.S. Department of the Army, Corps of Engineers, Hydrologic Engineering Center, HEC-HMS Hydrologic Modeling System, Version 1.0, Davis, California, March 1998. 45. Federal Emergency Management Agency, Guidelines and Specifications for Flood Hazard Mapping Partners, February 2002. 46. U.S. Department of the Army, Corps of Engineers, Portland District, Peninsula Drainage District No. 1, Detailed Product Report, Section 205, September 1996. 47. Philip Williams and Associates, Ltd., for City of Portland, FEMA Physical Map Revision Application for Johnson Creek, superseded LOMR Case No. 00-10-173P, January, 1, 2000. 48. City of Milwaukie, Federal Emergency Management Agency MT-2 Form 1, Appeals to Johnson Creek LOMR Case No. 00-10-173P, May 3, 2001. 49. Puget Sound LiDAR Consortium/Puget Sound Regional Council, Bare Earth LiDAR ASCII Points, Scale 1:12,000, Contour Interval 2 feet, Aerial Survey of March 13, 2004. 34
10.0 REVISIONS DESCRIPTIONS This section has been added to provide information regarding significant revisions made since the original FIS report was printed. Future revisions may be made that do not result in the republishing of the FIS report. To assure that users are aware of all revisions, it is advisable to contact the community repository of flood hazard data located at the City of Portland, Bureau of Environmental Services, 1221 SW 4 th Avenue, Room 230, Portland, OR, 97204. 10.1 First Revision [November 26, 2010] For this revision, the floodplain boundaries within the City of Portland for the Columbia River, Columbia Slough, and a portion of the Willamette River were revised based on 2 foot contour interval topographic data developed from LiDAR data created by the Puget Sound LiDAR Consortium (Reference 49). The data can be used at a horizontal scale of 1:12,000 (1 inch = 1,000 feet) or smaller. WEST Consultants, Inc. performed this work for the Federal Emergency Management Agency (FEMA), under Contract No. EMS-2001-CO-0068 and completed it in August 2008. The FIRM panels being revised are 0020, 0040, 0060, 0080, 0085, 0105, 0110, 0120, and 0140. The results of this revision were reviewed at the final CCO Meeting held on April 7, 2010. All problems raised at that meeting have been addressed in this revision. This revision also incorporates three Letters of Map Revision (LOMR). LOMR case number 05-10-0477P, dated July 20, 2005, revised BFEs for the Peninsula Drainage District No. 1 as shown on panels 0080 and 0085. Table 2 Summary of Elevations has been updated to reflect this data. LOMR case number 07-10-0004P, dated January 28, 2008, revised SFHA boundaries and BFEs for the area east of the Peninsula Drainage Canal and west of NE Airport Perimeter Road as shown on panels 0085 and 0105. Table 2 Summary of Elevations has been updated to reflect this data. LOMR case number 08-10-0276P, dated January 21, 2009, revised SFHA boundaries and BFEs along Johnson Creek in the vicinity of cross sections L through Q. This revision covers part of panels 0184 and 0203, which are not being revised at this time, however, the FDT, Profiles, and DFIRM DB do include this updated data. Other than the above LOMRs, no new engineering analyses were incorporated as part of this revision. 35
SOUTHEAST 82ND AVENUE
CITY OF PORTLAND MULTNOMAH COUNTY MULTNOMAH COUNTY CITY OF PORTLAND