Puget Sound Floodplains Mapping Project. Presented by CORE GIS March 18, 2011

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1 Puget Sound Floodplains Mapping Project Presented by CORE GIS March 18, 2011

2 Acknowledgements This project was conducted for the National Wildlife Federation, with funding from NWF and the Mountaineers Foundation

3 Project Background In 2004, NWF filed a successful lawsuit (NWF v. FEMA), asking the federal government to assess whether NFIP harms ESA-listed salmon. The resulting Biological Opinion 1 (BiOp) concluded that NFIP jeopardizes the continued existence of salmon and orcas in Puget Sound and therefore must be modified. The federal analysis estimates that if changes are not made, the NFIP program could be responsible for a 30% decline in wild Chinook in Puget Sound waters. 1 The Biological Opinion is officially titled Endangered Species Act Section 7 Consultation Final Biological Opinion and Magnuson-Stevens Fishery Conservation and Management Act Essential Fish Habitat Consultation: Implementation of the National Flood Insurance Program in the State of Washington Phase One Document Puget Sound Region, prepared by National Marine Fisheries Service Northwest Region, September 22, 2008.The BiOp can be downloaded at:

4 What did we set out to do? Help NWF ensure that the 2008 FEMA Floodplain Biological Opinion (BiOp) is implemented Produce maps and analyses for NWF to use in communicating floodplain issues to decision makers and the public

5 How did we do it? Maps Flood locations and severity Flood damages in dollars Repetitive loss, severe repetitive loss areas Floodplain loss over time and floods over time Development in floodplains over time Salmon habitat in floodplains Habitat in floodplains Hotspots Presence of PHS habitat polygons Presence of PHS points Percent impervious surface Number of structures

6 How did we do it? Analysis Statistics Flood costs Repetitive loss properties Floodplain delineation loss/change over time Assessed improvement value Floodplain Development Structures on parcels intersecting floodplains

7 Federal Flood Damage Public Assistance to Counties Total = $135,211,638

8 NFIP Payments by City, Total = $153,987,483

9 Repetitive Loss Properties Repetitive Loss Structure--An NFIP-insured structure that has had at least two paid flood losses of more than $1,000 each in any 10- year period since 1978.

10 Severe Repetitive Loss Properties A Severe Repetitive Loss Property is one: (a) That has at least four NFIP claim payments (including building and contents) over $5,000 each, and the cumulative amount of such claims payments exceeds $20,000; or (b) For which at least two separate claims payments (building payments only) have been made with the cumulative amount of the building portion of such claims exceeding the market value of the building.

11 Flood Frequency and Heights Above Flood Stage

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13 Measuring floodplain loss DFIRM maps are replacing the Q3 maps Where has floodplain been lost since the original delineations were made? Intersected Q3 and DFIRM to determine What stayed the same? Where was floodplain lost? Where was floodplain gained?

14 Floodplain loss over time Cedar River

15 Problems with measuring floodplain loss DFIRM updates still underway some counties Effective, some Intermediate, some Preliminary Changes may be actual floodplain loss; may be improvements in floodplain delineation methods The curse of the missing data acronyms! PMR: Physical Map Revision SOMA: Summary of Map Amendments LOMC: Letter of Map Change LOMR: Letter of Map Revision LOMA: Letter of Map Amendment CLOMR: Conditional Letter of Map Revision Etc Some are digital; most are not; all hard to find

16 Floodplain development over time, v1 Used NOAA CCAP to measure change in development between 1992 and 2006 This did not work out very well

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20 Floodplain development over time, v2 Using County Assessor data, indentified all parcels intersecting the union of Q3 and DFIRM floodplains across 8 counties Some counties provided data identifying whether or not a structure existed in parcels Where that information was absent, we used improvement value to represent a structure Using year built, mapped structures by decade Problems: parcel intersecting floodplain does not necessarily mean structure is located within floodplain; could be adjacent, uphill, etc Year built: ambiguity of effective vs actual

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22 7,209 Structures

23 5,384 Structures

24 8,188 Structures

25 7,358 Structures

26 28,139 Structures

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36 Assessed Improvement Value of All Properties Intersecting Floodplains Total Assessed Improvement Value of Properties Intersecting Floodplains 10/22/2010 County Number of Structures Market Improvement Value Grays Harbor 11,036 1,515,311,110 Thurston 5,095 1,374,376,950 Pierce 13,677 4,364,968,100 King 10,729 9,245,264,862 Snohomish 11,847 2,612,607,000 Skagit 11,279 2,401,292,127 Whatcom 8,822 1,861,419,216 Cowlitz 3,262 1,200,729,460 Kitsap 2, ,980,240 Mason 1 8,718 1,182,648,332 Lewis 2 5,932 1,363,250,703 Pacific 3 10,943 1,072,484,600 TOTAL 72,485 $ 23,375,239,365 1 Based on 2009 data 2 Based on 2007 data 3 Pacific county data should be consdired provisional due to the ambiguous nature of the assessed value field--there is only one field, called 'assessed' and it is unclear if this represents total assessed value, assessed land value, or assessed building value

37 Salmon Habitat

38 Hotspot Analysis 1. Percent impervious surface (from USGS NLCD) 2. Number of cells containing structures within a 10x10 cell moving window (cells containing a structure were coded 1, all others 0; the moving analysis window calculates a focal mean for each cell based on the surrounding 10x10 window) Resultant grid has a potential value range of 0-1, rescaled to using the formula ([GRID] - MYMIN) * ((NEWMAX - NEWMIN)/(MYMAX - MYMIN)) + NEWMIN 3. Percent of landscape covered by one or more priority habitat/species polygon within a 10x10 cell moving window 4. Number of cells containing PHS points within a 10x10 cell moving window (cells containing a PHS point were coded 1, all others 0; the moving analysis window calculates a focal mean for each cell based on the surrounding 10x10 window) Resultant grid has a potential value range of 0-1, rescaled to using the formula ([GRID] - MYMIN) * ((NEWMAX - NEWMIN)/(MYMAX - MYMIN)) + NEWMIN 5. The four grids all have a scale of 0-100; they were added together and divided by 4 to yield the final hotspot result.

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42 Questions!