63.8

69.9 68.5

48.145.9

54.2

56.4

58.9

65.7

47.6247.97

47.5147.94

46.2248.23

44.95

55.29

56.99

51.12

55.08

57.01

54.29

54.6753.23

59.13

59.35

59.52

60.72

60.93

63.5963.35

63.4262.02

62.85

62.21

63.27

65.2964.44

64.82

64.69

63.52

63.47

65.55

65.88

65.58

65.41 68.2365.85

66.16

66.3269.53

68.75 70.52

69.5169.44

70.3170.2869.41

69.7470.72

64.9368.75

70.6369.45

69.2166.63

68.4270.0366.92

45.73

45.96

47.57 45.4547.41 46.66

47.0146.86

48.12

49.82

50.4251.08

50.71

50.12

52.2451.63 51.86

49.6351.25 52.71

53.04 55.1356.28

57.02

55.71

55.21

56.18

56.17 56.0157.17

53.64

55.33

57.3556.04

58.7858.78

57.59

56.14

60.9158.01

60.51

60.45

58.32

63.11

63.4761.48

64.71

60.5959.29 61.4858.62

55.25

63.95

64.62

69.0868.99 69.14

65.67

66.61

67.47

67.51

68.54

68.5466.93

68.07

U.S. DEPARTMENT OF THE INTERIOR Prepared in cooperation with the SCIENTIFIC INVESTIGATIONS REPORT 2010–5177U.S. GEOLOGICAL SURVEY FEDERAL EMERGENCY MANAGEMENT AGENCY Magnitude and extent of flooding on Stillaguamish River—PLATE 7

science for a changing world Mastin, M.C., Gendaszek, A.S., and Barnas, C.R., 2010, Magnitude and Extent ofFlooding at Selected River Reaches in Western Washington, January 2009

Map showing magnitude and extent of January 2009 flooding on river mile 12.3 to 17.7, Stillaguamish River, Snohomish County, Washington. By

Mark C. Mastin, Andrew S. Gendaszek, and Christiana R. Barnas2010

3,0000 1,000 2,000 6,000 FEET4,000 5,000

0 500 1,000 1,500 2,000 METERS

3,0000 1,000 2,000 6,0004,000 5,000

0 500 1,000 2,000 2,500 METERS

9,000 FEET7,000 8,000

1,500

47.8

4

51.63

51.38

47.6

0

47.4

3

63.00

46.2

2

55.03

46.1

5

69.355.96

55.85

56.07

57.21

45.97

69.11

69.11

57.73

62.4

9

45.75

56.50

58.29

63.03

63.08

63.75

62.89

55.73

58.74

59.24

52.12

61.95

63.28

63.43

50.9

1

59.48

65.4

52.63

70.3

48.0

4

65.86

70.250.2

7

65.78

60.62

47.4

8

69.42

52.9

6

61.34

63.89

49.3

9

60.78

54.51

60.91

64.37

69.83

70.0969.98

68.54

67.98

53.1

9

66.43

54.02

68.9

8

48.12

68.9

8

47.84

51.38

55.03

Barrier preventing water surface interpolation

Estimated flood depth, in feet

EXPLANATION

High-water marksRiver centerline

Less than 2.01

2.01 to 4.00

4.01 to 6.00

6.01 to 10.00

10.01 to 14.00

14.01 to 24.00

63.89

Note: See belowRiver mile posts (RM)17

River centerline

47.51

46.66Used in final mapNot used

EXPLANATION

High-water marks, with elevation in feet above NAVD 88

1

GIS mask used to eliminate areas from the flood analysis

Stillaguamish

River

Potential water-surface contour in feet, interval is variable. Datum is NAVD 88

1313

1414

1515

151616

1717

1818

00

11

1

2

Note: Small unconnected mapped areas of inundation may or may not have been flooded.Note 1: Landowner says floodwaters did not come over Highway 530 at his property, but crossed highway farther to the west and came around from the south to near his home along the creek. His home did not flood.Note 2: Landowner says floodwaters did not come over the left river bank, but came onto his property from overbank flows farther upstream.Note 3: Water flowed over the highway at this location according to Max Albert, Stilliguamish Flood Control District.Note 4: The water-surface contours at the approximate locations where flood waters were thought to cross Highway 530 were extended to the likely southern limit of flooding so that the analysis would extend this far.Note 5: There were reports of flooding on this side of Highway 530 in this area from flow through culverts (Max Albert, Stilliguamish Flood Control District).Note 6: A large breech of the levee was found here (State Plane North, NAD 83 coordinates: 440,513.3 1,323,117.2)Note 7: A large breech of the levee was found here (State Plane North, NAD 83 coordinates: 440,695.2 1,321,290.3)

Source of aerial photography: National Agricultural Imagery Program, 2008

3

4

5

6

7

48°12'

48°11'

48°13'

48°12'

48°11'

122°12' 122°10' 122°08'

122°12' 122°09' 122°06'

High : 419.62 feet

Low : 27.95 feet

Lidar data–Hillshade and non-linear color scale

I-5

I-5

SR9

SR9

Arlington

A

B