Floods in the 

Skagit River Basin 

Washington

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1527

I AN 2 21962

Floods in the 

Skagit River Basin 

Washington

By JAMES E. STEWART and G. LAWRENCE BODHAINE

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1527

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1961
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

The U.9. Geological Survey Library has cataloged this publication as follows:

Stewart, James E 1933--

Floods in the Skagit Kiver basin, Washington, by James E. 

Stewart and G. Lawrence Bodhaine. Washington, U.S. Govt. 

Print. Off., 1961.

v, 65 p. illus., maps (part fold., part col. in pocket) diagrs., tables. 

24 cm. (U.S. Geological Survey. Water-supply paper 1527)

Bibliography: p. 63.

1. Floods Washington (State)-Skagit River basin. 2. Stream 

measurements Washington (State) I. Bodhaine, George Lawrence, 

1917- joint author. II. Title. (Series)

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington 25, D.C.
CONTENTS

Page

Abstract______________________________________ 1

Introduction._____________________________________________________ 1

Description of the basin____________________________________________ 4

Geography___ _______________________________________________ 4

Climate-_____________________________________________________ 6

Geology______________________________________________________ 8

Description of floods.______________________________________________ 9

Winter floods.________________________________________________ 9

Summer floods________________________________________________ 11

Duration of peaks.____________________________________________ 11

Short-duration flood of November 1949 _____________________ 11

Long-duration flood of February 1951___________---__________ 13

Effect of reservoirs. _ ___________________________________________ 14

Dikes on lower Skagit River___-___--___--_-_-__________________ 17

Flood profile-----------------__________.___________ 17

Flood plain.__________________________________________ 18

Flood damage_-------_---_--____--____________-_____________ 18

History of floods.___________________________________________ 20

Historic flood data ___________________________________________ 22

Indian legend flood of about 1815______________________________ 25

Tree-staining flood of about 1856--_----------_--___---__-_-___ 26

Floods of 1880, 1882, and 1894__________________________________ 27

Flood of November 1897______________________________ 27

Flood of November 1909___________________________ 28

Flood of December 1917____________________________ 29

Flood of December 1921________________________ 29

Flood of February 1932..__________________________ 29

Flood of November 1949___________________________ 30

Flood of February 1951______________________________ 30

Flood records.____________________________________________________ 31

Gaging station records------_______---_-_-_-_-____--___-__--__- 31

Skagit River near Hope, British Columbia.___________________ 32

Skagit River above Devils Creek, near Newhalem, Wash.______ 32

Beaver Creek near Newhalem, Wash______________--____-____ 33

Skagit River near Newhalem, Wash________________________ 33

Ruby Creek below Panther Creek, near Newhalem, Wash______ 34

Skagit River below Ruby Creek, near Newhalem, Wash-_______ 35

Ross Reservoir near Newhalem, Wash______________________ 35

Thunder Creek near Newhalem, Wash______-___---------___- 36

Diablo Reservoir near Newhalem, Wash______________________ 37

Skagit River at Reflector Bar, near Newhalem, Wash._________ 38

Stetattle Creek near Newhalem, Wash.______________________ 39

Skagit River at Newhalem, Wash__________________________ 40

in
IV CONTENTS

Flood records Continued

Gaging station records Continued Page

Skagit River above Alma Creek, near Marblemount, Wash_____ 41

Bacon Creek near Marblemount, Wash-.-____________________ 41

Skagit River at Marblemount, Wash_______________________ 42

Cascade River at Marblemount, Wash_______________________ 42

South Fork Sauk River near Barlow Pass, Wash.____________ 43

Sauk River above Whitechuck River, near Darrington, Wash___ 44

Sauk River at Darrington, Wash_-----------_-----------____ 44

Suiattle River near Mansford, Wash_________________________ 45

Sauk River near Sauk, Wash-_-_______--__-__--___--____-__- 46

Baker River below Anderson Creek, near Concrete, Wash______ 47

Lake Shannon at Concrete, Wash___---_--___---_-_---__--__- 48

Baker River at Concrete, Wash__ ___________________________ 49

Skagit River near Concrete, Wash___________________________ 50

Alder Creek near Hamilton, Wash___________________________ 51

Day Creek near Lyman, Wash______-___-___-______________- 51

Skagit River near Sedro Woolley, Wash._____________________ 52

East Fork Nookachamps Creek near Clear Lake, Wash_________ 52

Skagit River near Mount Vernon, Wash.__-________-__-_-__-_ 53

Frequency of floods--_---__--___-.___---_--_---_--_----_----_----_-- 53

Single station frequency-____-_______-_--_------_-_--_---------- 53

Frequency series------------------------------------------- 54

Plotting positions______-___--___---__--_----_----__---_-- 54

Historical data_____________-___--------------_--_-_------- 55

Fitting frequency graphs-_____-___--____-___----_-______--- 56

Regional frequency._________-_______-_____--_-_-------_-----_- 56

Selection of base period.__________-____--__-_-____-___--___ 57

Comparable means---------------------------------------- 57

Test for homogeneity____--_--_-_--------_----------------- 58

Combining records____________-__-_-__---_---__--_-_----- 58

Flood-frequency relationships.______________________________ 59

Flood-frequency curves.-______-___-____-____--__---_---__-- 60

Selected bibliography________________-__-_-__________--_-_-_-_--_-_ 63

Index.____________________________._____-_______-______-_-- 65

ILLUSTRATIONS

Page 

PLATE 1. Map of Skagit River basin showing location of gaging stations

and general features-______-_--__-----_----_--____- In pocket

2. Map of Skagit River basin showing major dike failures-- In pocket

3. Views of the flood of 1951 in vicirity of Conway,

Wash..____________________________-._-facing 2

4. Views of the flood of 1951 near Mount Vernon and

Hamilton________________________________.facing 3

FIGURE 1. Hydrographs of short duration flood peaks. _____ _____ 12

2. Hydrographs of long-duration flood peaks. _____-____-_- 13

3. Capacity curve for Ross Reservoir___-_____-_-_-___---_-_- 15

4. Hydrograph showing effect of dams on flood peaks-.._______ 16

5. Flood profiles.----------------------------------------- 18

6. Map showing area probably inundated by major flood....--- 19
CONTENTS V

Page 

FIGURE 7. Composite flood-frequency curve, Skagit River basin______ 58

8. Variation of mean annual flood with drainage area________ 60

9. Frequency of annual floods, Skagit River at Newhalem, Wash- 61

10. Frequency of annual floods, Cascade River at Marblemount,

Wash______---____-_____________- -_-_-____----_- 61

11. Frequency of annual floods, Sauk River at Darrington, Wash. 62

12. Frequency of annual floods, Baker River below Anderson

Creek, near Concrete, Wash----_-----_---____-------__- 62

13. Frequency of annual floods, Skagit River near Concrete,

Wash________________.. _____________ 62

14. Frequency of annual floods, Skagit River near Sedro Woolley,

Wash___________________.____________ 63

FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

By JAMES E. STEWART and G. LAWRENCE BODHAINE

ABSTRACT

According to Indian tradition, floods of unusually great magnitude harassed 

the Skagit River basin about 1815 and 1856. The heights of these floods were 

not recorded at the time; so they are called historical floods. Since the arrival 

of white men about 1863, a number of large and damaging floods have been 

witnessed and recorded.

Data concerning and verifying the early floods, including those of 1815 and 

1856, were collected prior to 1923 by James E. Stewart. He talked with many 

of the early settlers in the valley who had listened to Indians tell about the 

terrible floods. Some of these settlers had referenced the maximum stages of 

floods they had witnessed by cutting notches at or measuring to high-water 

marks on trees. In order to verify flood stages Stewart spent many weeks 

finding and levelling to high-water marks such as drift deposits, sand layers in 

coves, and silt in the bark of certain types of trees.

Gaging stations have been in operation at various locations on the Skagit 

River and its tributaries since 1909, so recorded peak stages are available at 

certain sites for floods occurring since that date. All peak discharge data 

available for both historical and recorded floods have been listed in this report.

The types of floods as to winter and summer, the duration of peaks, and the 

effect of reservoirs are discussed.

In 1899 Sterling Dam was constructed at the head of Gages Slough near Sedro 

Woolley. This was the beginning of major diking in the lower reaches of the 

Skagit River. Maps included in the report show the location of most of the 

dike failures that have occurred during the last 73 years and the area probably 

inundated by major floods. The damage resulting from certain floods is briefly 

discussed.

The report is concluded with a brief discussion of the U.S. Geological Survey 

method of computing flood-frequency curves as applied to the Skagit River 

basin. The treatment of single-station records and a means of combining these 

records for expressing regional significance are exemplified. Historical data are 

used in the development of both the single-station and the regional curves.

INTRODUCTION

Skagit River, the largest in northwestern Washington, rises in the 

main Cascade Range and empties into Skagit Bay near Mount 

Vernon. The total drainage area is about 3,100 square miles, of 

which 400 square miles are in Canada. A map of the area shows 

location and general features on plate 1.

1
2 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

The date of the first exploration of the Skagit Valley is unknown, 

but Hudson's Bay and Northwestern fur trappers probably started 

working the Skagit Valley about 1810. The first white settlement 

on the delta at Mount Vernon occurred about 1863. The actual 

settlement of the valley upstream from the delta started about 1878 

when gold was discovered on Ruby Creek, which empties into the 

Skagit River at the point where the river starts to break through 

the secondary Cascade barrier. With the impetus of excitement over 

gold, there was a comparatively rapid influx of population to the 

whole valley. However, the gold-boom settlement of about 5,000 

people on Ruby Creek died out within a very few years. The main 

increases in permanent valley population have occurred since the 

Northern Pacific Railway pushed northward across the Skagit delta 

in 1890, and have been attributable mainly to logging and lumbering, 

mining, and agriculture.

The Skagit River valley has a history of floods that dates from 

about 1815. The basin has been subjected to several damaging 

floods since the year 1863 when it was first settled by white men. 

Indian legends indicate that even greater floods occurred in the nineteenth century prior to 1863. The exact elevations of all of these 

floods are not known, but their relative magnitudes have been fairly 

well determined by intensive research and study in the valley. A 

brief resume of the floods is as follows:

1. About 1815: Highest flood.

2. 1856: Second highest flood.

3. 1880, 1882, and 1894: Spring floods that inundated lower valley for long period.

4. November 16, 1896: Highest flood since the settlement of the valley in or 

about 1878 and probably the highest since 1856.

5. November 19, 1897: Floods everywhere higher than the 1896 flood, especially 

high from the mouth of the Cascade River to just below Birds view. In 

general, in this section of the river the 1897 peak has not been exceeded 

to date (1958). The 1897 flood rose with remarkable suddenness, due to 

a very warm Chinook wind and heavy rain. The Cascade, Sauk, and 

Baker Rivers were very high and caused a high peak in the Skagit River 

near the mouth of each stream. Owing to the sudden starting and stopping of flood conditions, the peaks were rapidly reduced by channel storage 

as the crest moved downstream.

6. November 16, 1906: Flood exceeded the 1897 flood in the diked districts on 

the delta, because of the dikes. In all other sections of the river the flood 

of 1906 was lower than that of 1897.

7. November 30, 1909: Since the settlement of the valley, this flood has exceeded 

all floods from the headwaters in Canada to the mouth of the Cascade 

River; the same is true from just below Birdsview to the sea, except where 

log jams forced the floods of 1897 and 1921 to higher elevations.

8. December 30, 1917: Flood was remarkable for the length of time it remained 

high, rather than for its peak stage. Comparable to 1896 and 1906 flood 

in regard to height. The damage on the delta was due partly to the long 

flood period producing a great deal of overflow after the dikes had broken.
GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1527 PLATE 3

4, Aerial view of Conway and vicinity.

B, North Fork distributary below the bridge on U.S. Highway 99, showing the break in the dike. Photographs

by U.S. Army Corps of Engineers.

FLOOD OF 1951 IN VICINITY OF CONWAY, WASH.
GEOLOGICAL SURVEY WATEK-SUPPLY PAPER 1527 PLATE 4

A, View upstream from Great Northern Railway bridge north of Mount Vernon.

B, Aerial view of town of Hamilton and valley downstream. Photographs by U.S. Army Corps of Engineers.

FLOOD OF FEBRUARY 1951 IN VICINITY OF MOUNT VERNON AND 

HAMILTON, WASHINGTON
INTRODUCTION 3

9. December 12, 1921: Flood was nearly as great as the flood of 1909 and in 

most of the basin was higher than the flood of 1917.

10. February 1932: Flood would have been much more serious if there had been 

no upstream storage. Peak at gaging station on Skagit River (in a canyon known locally as "The Dalles") near Concrete was estimated to have 

been reduced by 35,000 cfs. Natural discharge at The Dalles estimated 

to be about 40,000 cfs less than the 1917 flood.

11. November 1949: Upstream storage estimated to have reduced the peak at 

The Dalles near Concrete by 45,000 cfs. Under natural conditions this 

flood probably would have been greater than the 1932 flood and onlv 

slightly binaller than the 1917 flood.

12. February 1951: Estimated natural discharge less at The Dalles near Concrete 

than for any of the above floods. Because of the long duration of this 

flood, the crest reaching Mount Vernon had been reduced very little by 

channel storage and exceeded the 1949 flood at that location by about 2.5 

feet.

Major floods have caused considerable monetary damage, especially 

in the lower reaches of the valley. Estimates of known flood losses 

compiled by the U.S. Army Corps of Engineers total $4,850,000 from 

1894 to 1932. The number of lives lost is not known.

Floods of recent years have been less damaging because they have 

been of lesser magnitude and the power dams in the upper reaches of 

the river have provided some storage.

In 1922, as a result of damage from the 1921 and earlier floods, there 

was a desire by those suffering damage to have studies initiated as a 

preliminary step to possible flood protection measures. Dikes had 

been built to confine the lower reaches of the river but they offered 

protection only against the lesser floods. The first logical step was to 

determine the size of the floods to be controlled. Kepresentatives of 

Skagit County made arrangements with G. L. Parker, then district 

engineer of the U.S. Geological Survey Surface Water Branch at 

Tacoma, to determine the sizes of the floods. J. E. Stewart was given 

the assignment of compiling field data and writing a preliminary report, which was completed in 1923 but not published.

In the study for the 1923 report, redeterminations were made of the 

peak discharge of such floods as had occurred on the streams in the area 

since the beginning of streamflow records. Also, approximate calculations were made of the peak discharge of all the great floods that 

occurred between the time of the first white settlement of the Skagit 

Valley and the beginning of the streamflow records. In addition, field 

investigations and computations were made of the stage, discharge, and 

approximate dates of two great floods that occurred prior to the arrival 

of the first white settlers. The conclusion was reached that the 

earlier and greater of these two floods probably was as large or nearly 

as large as the greatest flood that has occurred here within the last 

several hundred years. Information of floods, occurring before 1863,
4 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

was handed down orally by the Indians, and by finding silt and stains 

in the bark of trees and sand deposits in protected coves along the 

stream.

The 1923 report recommended that certain areas be given early 

flood protection and that a warning system be installed. Also, suggestions were made as to some preliminary steps toward permanent 

flood protection. The pertinent data from the report written by J. E. 

Stewart are included in this report. Interest in the report was revived 

in 1942 by F. M. Veatch, who succeeded G. L. Parker as district 

engineer. As a result, some work on it was done in the Washington 

office during the next few years, chiefly by W. S. Eisenlohr, Jr. In 

1949 additional field data were obtained, and work was resumed to 

evaluate previous data. Most of this report was written by G. L. 

Bodhaine, Tacoma district. He used the basic data and reports of 

J. E. Stewart and recent data concerning floods hi the Skagit River 

basin.

The present report contains discussions of many features bearing on 

the magnitudes of past and present floods, of the geologic history as it 

may affect floods and flood evidence, and of dike failures and inundated 

areas. It also contains a regional flood-frequency study based on the 

methods most recently developed by the U.S. Geological Survey.

Good photographs of the earlier historic floods are not available, but 

pictures were obtained by the U.S. Army Corps of Engineers during 

the flood of February 1951. These pictures were taken at noon a few 

hours after the peak, which occurred at about 7 a.m. on February 11 

near Mount Vernon, and are presented as plates 3 and 4.

The photographs on plate 3 were taken in the area of the distributaries near the mouth of the river where dike breakage occurred. 

Plate 3 A shows the inundated area in the town of Conway and vicinity. 

Levee break on the North Fork distributary is shown in plate 3B.

Plate 4A shows the inundated area between the railroad bridge 

north of Mount Vernon (just upstream from the gaging station near 

Mount Vernon) and the town of Sedro Woolley. The flood at the 

town of Hamilton, about 12 miles upstream from Sedro Woolley, is 

shown in plage 45.

DESCRIPTION OF THE BASIN 

GEOGRAPHY

The Skagit River may properly be said to head in Skaist Creek, its 

most upstream tributary, of which the most northerly branch begins 

on the slopes of Skaist Mountain in British Columbia, Canada, about 

20 miles north of the international boundary. From there, the river 

flows in a generally southwestward direction for about 25 miles; 

thence about 7 miles in a generally southeastward direction to a point
DESCRIPTION OF THE BASIN 5

about 2 miles north of the international boundary; thence in a generally 

southward direction to a place in the State of Washington about 20 

miles south of the international boundary, where it turns southwestward and begins to break through the Skagit Range.

Through the Skagit Range the river flows in a deep, narrow, steep, 

and almost continuous canyon about 10 miles long. This section of 

the river is now the center of a great hydroelectric-power project of 

the city of Seattle. The project involves three major developments; 

namely, Ross (formerly Ruby), Diablo, and Gorge.

The Ross development at the head of the canyon involves a dam 

that, when completed, will raise the water more than 600 feet and 

create a reservoir with capacity of 3,450,000 acre-feet, completely 

controlling the normal river flow below that point and a powerhouse 

that ultimately will have a capacity of 360,000 kilowatts. At present, 

the dam is 540 feet high, provides 1,400,000 acre-feet of storage, and 

supplies water to 3 generators producing a total of 270,000 kilowatts.

The Diablo development is located at about the center of the 10- 

mile section of canyon. It involves a dam that raises the water 325 

feet and backs it to the toe of Ross dam, but there is a reservoir 

capacity of only 90,000 acre-feet because of the narrowness of the 

canyon. A powerplant of 132,000 kilowatt capacity has been completed and is in operation.

The Gorge powerplant now has a capacity of 108,000 kilowatts. 

The development consists of a temporary masonry diversion dam 

and 11,000 feet of 20.5-foot diameter tunnel which furnishes a head of 

294 feet at the powerhouse. The temporary diversion dam is now 

being replaced by a permanent dam more than 100 feet high which 

will back water to the toe of Diablo dam but will provide only about 

6,000 acre-feet of storage. The head on the Gorge plant will thereby 

be increased to 385 feet and the plant capacity, including the additional units being installed, will be 153,000 kilowatts.

The foregoing developments, mainly Ross, will materially reduce 

flood flows downstream and particularly reduce the smaller floods.

The drainage area where the river emerges from its canyon section 

at the Gorge powerplant is about 1,160 square miles. After leaving 

the canyon section, the Skagit River within a distance of 20 miles 

is enlarged by the Cascade, the Sauk, and the Baker Rivers, its three 

largest tributaries. Near the mouth of the Sauk River, the Skagit 

River changes its general direction from southwest to west. It 

emerges upon its delta plain about 35 miles farther downstream near 

the city of Sedro Woolley, where the drainage area is about 3,000 

square miles. At Sedro Woolley, the river again changes its course 

to southwest and flows along the southeastern and landward side of 

its delta. Finally, it divides into typical delta distributaries and
6 FLOODS IN THE SKAGFT RIVE-R BASIN, WASHINGTON

empties into Skagit Bay which lies nearly east of the Straits of Juan 

de Fuca. The Skagit River delta is about 45 miles south of the 

international boundary.

The following table shows the locations of various features with 

respect to the mouth of the Skagit River at Skagit Bay:

Location

Miles 

above 

mouth

0.0

7.0

10.2

H e

17.4

21.1

f»A 1

Af\ O

AA ^

52.6

55.0

65.7

76.6

77.2

81.4

Location

Diablo Dam... _______________

Miles 

above 

mouth

84.2

92.2

95.3

98.5

99.3

99.6

100.9

103.8

104.0

104.8

106.0

108.8

116.1

134.0

138.8

Many times in the past, the river in its lower course, even upstream 

from the delta, has abandoned its channel and many of these abandoned channels remain as sloughs through which a little water flows, 

even during low river stages.

CLIMATE

The climate of the North Pacific coastal region, in which lies the 

greater portion of the Skagit basin, is mild and moderately moist 

owing to the prevailing westerly air currents that advance inland 

from the Pacific Ocean, and to the shielding effects of the Cascade 

Range, which serve to exclude and deflect the cold continental air 

towards the east. The prevailing westerly air currents cross vast 

reaches of the ocean, and acquire much water vapor and a temperature 

near that of the sea. The air currents receive their warmth and moistness from the general currents of the ocean rather than from the 

Japanese current, the Kuroshio, which curves northward into Alaskan 

waters. As a result of the rather steady influx of marine air the 

winters are comparatively warm and the summers cool. Extremes 

of heat or cold are moderate and of short duration, and the daily 

range of temperatures is small.

The main river valley lies very nearly along latitude 48° 30' which 

is slightly north of the northern tip of Maine and approximately in 

the latitude of St. Johns, Newfoundland. The midwinter temperatures are similar to those on the Atlantic coast at latitudes several 

hundred miles farther south.

Heavy rains or snows, especially in winter, occur when the moistureladen winds encounter the cool higher altitudes of the Coast and
DESCRIPTION OF THE BASIN

Cascade Ranges. Large quantities of snow seldom fall at sea level. 

During especially warm winter weather, rain may prevail up to elevations of nearly 6,000 feet. When combined with melting snow, 

the rains often result in severe floods in the lower, heavily settled 

section of the Skagit River valley.

The climatological stations within the Skagit basin are, in general, 

at low elevations; therefore, the actual temperature and precipitation 

at high elevations are not known. The following table shows meteorological data for stations in the Skagit basin, including data for the 

warmest, coldest, wettest, and driest months:

Station

Elevation 

in feet 

above mean 

sea level

30 

56 

270 

525 

550

Mean temperature (°F)

Jan.

39.1 

37.7 

35.2 

33.5 

34.1

Aug.

61.6 

62.1 

64.9 

65.8 

62.6

Annual

50.6 

50.4 

50.9 

50.3 

48.7

Mean precipitation 

(inches)

July

0.67 

1.36 

1.13 

1.29 

1.27

Dec.

4.00 

6.35 

9.32 

12.00 

13.63

Annual

26.6 

45.5 

60.8 

72.6 

76.0

The average annual depth of runoff from the Skagit basin above 

Concrete is about 74 inches. Therefore, the average annual rainfall 

over the basin must be about 94 inches because evaporation, transpiration and other losses generally are considered to consume approximately 20 inches of the rainfall in this type of country.

The upper or southward-flowing section of the Skagit River and 

its tributary basin lie between ridges of the Cascade Range and are 

somewhat isolated from the coastal marine climate. The minimum 

altitude of that section of the river is about 1,200 feet; and, consequently, the winter snow is retained until spring and summer to a 

greater extent than in the lower section of the river. Furthermore, 

before reaching the upper part of the basin, the atmosphere, in passing 

over the first ridges of the Cascade Range, becomes considerably 

depleted of its heat and moisture. As a result of the natural isolation 

afforded the upper part of the basin, the runoff is much less than from 

the lower area. For comparison the runoff at several gaging stations 

for the period 1941-55 is listed below:

Station 

Skagit River near Hope________-______-_-..-____--_-.

Skagit River at Newhalem____. ____________________

Skagit River near Concrete__-___-________--_____---.

Skagit River near Mount Vernon______-_____-___-_-_.

Sauk River near Sauk_____________________________

Cascade River at Marblemount.-__________-____._-_.

Baker River at Concrete... _________________________

Runoff Drainage area 

(inches) (square miles')

38.6

50. 1

74.2

70. 7

81.5

80.9

115.2

357

1, 160

2,700

3,060

714

171

297
8 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

Several prominent mountain peaks border the Skagit basin in the 

ramifying branches of the Cascade Range. The two highest peaks 

are Mount Baker, 10,800 feet, and Glacier Peak, 10,400 feet. Several 

peaks are more than 9,000 feet and many more than 8,000 feet. 

Owing to the high altitude and heavy precipitation, the higher peaks 

are mantled with glaciers and snow fields which are productive of a 

heavy runoff during the summer and fall periods of low rainfall.

GEOLOGY

Prior to the glacial epochs, the Sauk and Suiattle Rivers formed a 

part of the Stillaguamish drainage basin.

During the glacial ages, the Skagit basin was much more heavily 

mantled with local ice than at present. In addition, the Skagit delta 

was overrun by an invasion of ice from Canada. The Canadian ice 

sheet, augmented by local glaciers in the State of Washington, pushed 

southward through the Puget Sound area between the Cascade Range 

and the Coast Ranges until it passed latitude 47° N., and established 

its terminal moraine a short distance north of Centralia, nearly 170 

miles south of the Canadian border. The Skagit River was blocked 

not only by this tremendous glacier near its mouth, but also further 

upstream near the town of Concrete where a large local glacier came 

down the Baker River valley.

The dam formed by one of the glaciers forced the Skagit River to 

cross a pass, now occupied by the lower Sauk valley, into the Suiattle 

River basin. During a portion of this glacial epoch, while the ice 

dam held, the entire Skagit River above Concrete poured across the 

Skagit-Suiattle divide and thence down the Stillaguamish River. The 

ice dam probably held for many thousands of years and during this 

time the Skagit-Suiattle pass was rapidly cut down to form a regular 

river channel. After the glacial epoch, the Skagit River returned to 

its old lower valley and was able to capture the Suiattle and Sauk 

Rivers from the Stillaguamish River through the new channel cut 

through the Skagit-Suiattle divide.

In the Puget Sound region there were great changes in elevation 

during the glacial epochs. Geologists have stated that during various 

geologic eras this region probably has been as much as 1,000 feet 

higher and perhaps 300 feet lower than it is at the present time. 

During the various glacial actions the stream valleys became deeply 

filled with glacial drift. It may be nearly 1,000 feet to bedrock in 

the old river channel on the Skagit delta. Construction projects 

have shown about 110 feet of depth to bedrock at Gorge Dam and 

about 30 feet to bedrock at Ross Dam.

The most abundant rocks in the Skagit valley between Marblemount and Sedro Woolley are unmetamorphosed andesite and basalt
DESCRIPTION OF FLOODS 9

associated with unmetamorphosed to slightly metamorphosed sedimentary rocks such as slate, greywacke and subordinate amounts of 

limestone, and low-grade metamorphosed equivalents, such as phyllite 

and green schist. All these rocks are pre-Tertiary. Tertiary sandstones are less abundant. There are local small outcrops of serpentinite. Higher up in the valley from Marblemount up are metaquartz diorite, schist with minor serpentinite pods, quartz diorite and 

granodiorite, and gneiss of the Skagit volcanic formation of Daly 

(1912).

In many places the sandstones are completely covered by glacial 

debris. Throughout the valley, there are many clay deposits in the 

hillsides. Some coal is present in the lower reaches of the valley.

DESCRIPTION OF FLOODS

The Skagit River is subject to two distinct types of floods winter 

and summer. In the past, most of the exceptional winter floods have 

occurred in November or December; the summer floods in May or 

June.

The largest flood during the winter of 1878-79 occurred on March 

17, 1879, and the largest flood during the winter of 1914-15 occurred 

on April 2, 1915. Since the arrival of the first white settlers, these 

two floods, produced by factors that ordinarily bring about winter 

floods, occurred on the latest dates known for winter floods.

The earliest date that a crest of a true summer flood is known to 

have occurred was May 11, 1910. A recent early summer flood 

occurred on May 13, 1949. On the basis of the assumption that these 

are the latest winter and the earliest summer floods that are likely to 

occur, a time interval of about a month is all that exists between the 

two types of floods.

In summer when the lowlands are overflowed, the crops are damaged by the long continued high stages of the snow-melt floods. 

However, winter floods cause the greatest overall damage because the 

crest heights of the winter floods are higher on the average than those 

of the summer floods.

WINTER FLOODS

Large winter floods in the Skagit River basin are caused by water 

released through the action of strong and long-continued winds which 

bear warm moistureladen atmosphere from the Pacific Ocean to the 

Cascade Range; this action causes precipitation and snowmelt. These 

winds are known locally, at least, as "chinook" winds and are caused 

by air currents blowing toward the center of an area of low barometric 

pressure.
10 FLOODS IN THE SKAGIT RIVEiR BASIN, WASHINGTON

Dr. Charles F. Brooks, secretary of The American Meteorologic 

Society, in No. 117 of "Why the Weather," states,

The chinook is the warm wind of the northwest. Its name is that of a tribe of 

Indians from the direction of whose camp the warm southwest wind reached the 

trading post, Astoria, at the mouth of the Columbia River. The use of the name 

soon spread to all warm winds in winter in the Northwest; and now the term is 

applied mostly to warm winds descending onto the Great Plains after passing 

over the Rocky Mountains.

Precipitation is produced during a chinook when the air currents, 

as they are being forced up and over a mountain barrier, reach a 

higher altitude than the condensation level.

The floodwater released through the action of a chinook is composed 

of both rainwater and water from melted snow and ice. The rainwater and part of the water from snow and ice are from precipitation 

that occurs during the chinook in the form of rain, snow, and sleet. 

The remainder of the floodwater results from the melting of old snow 

and ice, which consists not only of snow but also of rainwater that has 

been absorbed and entrapped by the snow during earlier occurrences of 

precipitation.

A rainfall-runoff study for the Skagit River, based on discharge 

records at Sedro Woolley and precipitation records in the upper part 

of the basin, at and near Reflector Bar, was made by J. E. Stewart. 

This study shows that during the years 1909-23 the average yearly 

runoff in inches at Sedro Woolley was very nearly equal to the average 

precipitation at the upper basin sites. This indicates that a much 

heavier precipitation must have occurred at higher altitudes in order 

to provide the additional amount of water lost through evaporation, 

transpiration, retention, and ground water. These data show extremely heavy precipitation and high runoff during the months in 

which the greater floods occurred. For example, the precipitation in 

November 1909 was 27.7 inches and the runoff was 12.5 inches; in 

December 1917 the precipitation was 29.8 inches (7.4 inches occurring 

December 27-29) with a runoff of 14.1 inches; and in December 1921, 

12.8 inches of precipitation (10.21 inches occurring December 10-12) 

produced a runoff of 13.3 inches, which indicates the melting of large 

quantities of snow accumulated during the previous two months of 

heavy precipitation. These examples show that winter floods result 

almost entirely from the large quantities of precipitation that occur 

during a storm, but are supplemented to some extent by the melting 

of previously deposited snow.

Four of the highest floods for which the exact date of occurrence is 

known were in November in the years 1896, 1897, 1906, and 1909. 

Two other high floods occurred in December in 1917 and 1921. 

Precipitation records at Vancouver, Wash., show that the great flood 

of 1856 also occurred in December.
DESCRIPTION OF FLOODS 11

The flood profiles of the great winter floods vary in shape depending 

upon the length of time the flood lasts (short- or long-duration storm) 

and on the time of day the flood crests from the larger tributaries 

enter the main river channel.

SUMMER FLOODS

The crests of summer floods are caused mainly by the hot summer 

sun melting the glaciers and the snowfields in the high sparsely 

timbered or open areas. The crests of the summer floods are probably 

swelled to a minor degree by snowmelt from the heavily timbered 

regions which lie just below the glaciers and adjacent snowfields.

The peak stages of the greatest summer floods are considerably 

lower than those for the great winter floods. The summer floods, 

however, are of much longer duration and are greater in volume than 

the winter floods. The crops are growing at the time of summer 

floods and, if the dikes break, the great damage done is accentuated by 

the fact that the long duration and great volume of the floods prevent 

repairing of the dikes. The greatest summer flood was that of 1894 

comparing closely with those of 1880 and 1882. For two weeks the 

flood of 1894 remained higher than the highest peak of any of the 

recent summer floods. The flood of 1880 remained at a high stage for 

more than a month.

DURATION OF PEAKS

The duration of the flood peaks in the upper part of Skagit River is 

an important factor in determining whether the flood will be destructive in the lower reaches. This may be especially true of the large 

floods that do not quite reach the stages and discharges of the known 

great floods. The peaks of the floods of November 1949 and February 

1951 were selected to demonstrate this point. The peaks would have 

been considerably higher had there been no storage in the power 

reservoirs upstream, but this would not affect the comparison of the 

duration of the two peaks.

SHORT-DURATION FLOOD OF NOVEMBER 1949

The flood of November 1949 is a good example of the flattening of a 

flood crest as it moves downstream. The hydrographs of the peak 

that occurred at the gaging stations near Concrete and near Mount 

Vernon are shown in figure 1. Channel storage had a marked effect 

on the sharpness of the peak by the time the crest reached Mount 

Vernon. The peak discharge of 153,000 cfs near Concrete was reduced to 114,000 near Mount Vernon.

Precipitation records in the basin at time of this flood partly explain 

the reduction in crest in the lower reaches of the channel. The Sedro 

Woolley precipitation gage indicates that very little rainfall occurred

577864 61 2
12 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

160

Skagit River near Mount Vernon

20

27 28 29

NOVEMBER 1949

FIGURE 1. Hydrographs of short-duration flood peaks.

in the lower part of the basin. Weather records show that there was 

no snow on the ground as far upstream as Diablo Dam, and that the 

minimum and maximum temperatures at Diablo Dam were 39° and 

58°, respectively. The precipitation data are shown in the following 

table:
DBaOKIPTION OF FLOODS 13

November 1949

23.. 

2i.. .............................

25...............................

26..............................

271 

28 2

29.. . ..- .

Precipitation, in inches

Diablo Dam

2.00 

1.50 

1.67 

.95 

4.05 

.71 

.67

Skagit 

powerplant

1.03 

.93 

.68 

4.21 

.72 

.60 

.46

Marblemount

0.65 

.60 

.75 

2.57 

1.18 

.81 

.17

Concrete

0.43 

.32 

1.17 

1.43 

1.73 

.46 

.20

Sedro 

Woolley

0.09 

.37 

.46 

.28 

.32 

.29 

.09

i Peak near Concrete.

" Peak near Mount Vernon.

LONG-DURATION FLOOD OF FEBRUARY 1951

The flood of February 1951 is a good example of a flood crest of long 

duration. The peak near Concrete lasted many hours longer than the 

peak of November 1949 although it did not reach as great a discharge. 

The hydrographs of the crests that occurred at the gaging stations near 

Concrete and near Mount Vernon are shown on figure 2. It can be

140

Skagit River nea Mount Vernon

Skagit River n ar Concrete /

60

10 . 11 

FEBRUARY 1951

12 13

FJQUBE 2. Hydrographs of long-duration flood peaks.
14 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

seen that the duration of the peak reduced the effect of channel storage 

and that the peak downstream was increased by a large contribution 

from the low elevations.

Weather records show that on February 7, 15 inches of snow was on 

the ground. By February 11 this was reduced to 5 inches. No snow 

was on the ground at or downstream from Concrete. The temperature 

at Diablo Dam during the flood ranged from a minimum of 33° to a 

maximum of 53°. The precipitation data are shown in the following 

table:

February 1951

1. ...............................

8... ... .......

9. ...............................

10 i n^......... ............ ......

12.... ...... ...........

Precipitation, in inches

Diablo Dam

1.82 

2.61 

6.21 

3.76 

.61 

0

Skagit 

powerplant

0.67 

1.39 

3.02 

5.77 

2.89 

T

Marblemount

1.54 

2.29 

4.67 

2.76 

.43 

0

Concrete

1.03 

.80 

2.42 

1.10 

1.11 

0

Sedro 

Woolley

0.42 

.50 

1.83 

1.11 

.28 

0

1 Peak near Concrete.

2 Peak near Mount Vernon.

The large amount of precipitation in the lower reaches of the basin 

accounts for a part of the increase in peak discharge as the flood 

progresses downstream. Snowmelt would have added materially to 

the peak, if snow had been on the ground when the rain began.

EFFECT OF RESERVOIRS

The reservoirs in the upper Skagit River basin have had a material 

effect on the peak discharge of the river occurring since the dams 

were constructed. The dam on Baker River at Concrete was constructed in 1926 and has had an effect on many peak flows in Skagit 

River. Diablo Dam was constructed in 1930, and practically all 

peaks since that date have been reduced somewhat by storage in 

Diablo Reservoir. The first level in the construction of Ross Dam 

was completed in 1940, and all peaks since that date have been 

affected to some degree by storage in Ross Reservoir. By August 

1949, Ross Dam had been raised two more levels and was capable of 

reducing the peak to a great extent on all but the largest floods at 

that point. If Ross Dam is ever raised to its proposed ultimate 

height, another 125 feet, it will be capable of almost completely controlling the entire flow from the 980 square miles of the Skagit River 

drainage basin upstream from the dam. The amount flood peaks 

would be diminished is not known, but it may be assumed that the 

flow of all except extreme peaks would be considerably reduced. In 

all probability even peak flows as great as those of 1815 and 1856 

would be reduced by an appreciable amount.
DESCRIPTION OF FLOODS 15

1700

1600

1300

Proposed maximum level

0 4 8 12 16 20 24 28 32 36 

CAPACITY, IN 100,000 ACRE-FEET

FIGURE 3. Capacity curve for Boss Reservoir.

The storage capacity curve for Ross Reservoir at the present 

height of Ross Dam is shown in figure 3. The capacity at watersurface elevation 1,600 feet is 1,400,000 acre feet. The additions of 

only 125 feet of height, to elevation 1,725 feet, would increase the 

capacity to 3,450,000 acre-feet, or to more than double its present 

capacity.

During the floods of November 1949 and February 1951, Lake 

Shannon was held at practically a constant level at the time of the 

peaks, so the Baker River peaks were not appreciably reduced by 

storage. However, during both floods Diablo and Ross Reservoirs 

stored large volumes of flow, and the peak discharges on the Skagit 

River at the gaging station near Concrete were substantially reduced. 

It has been estimated that the peak flow of the November 1949 

flood at the gage near Concrete was reduced by 45,000 cfs owing to 

storage in the two main-stem reservoirs. This indicates a natural 

peak discharge of 200,000 cfs near Concrete which probably would 

have been of disastrous proportions in the lower valley even if the 

effect of channel storage on the sharp peak was considered. An 

estimate has been made that the peak discharge of the February 1951 

flood at the gage near Concrete was reduced 13,000 cfs by upstream 

storage. If this flow had not been stored, it probably would have 

increased the peak at Sedro Woolley and at Mount Vernon to about 

158,000 cfs as a result of the long peak, which also might have proved 

disastrous to the lower valley. The crest of the February 1951 flood
16 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

was at the top of the dikes in several places so an additional 13,000 

cfs probably would have caused a failure at some point.

A study of the effect of upstream storage on the peak of the 

February 1932 flood at the gaging station near Concrete was made 

by G. L. Parker. Figure 4 shows the computed results. Diablo 

Dam and Baker Dam were the only ones in existence in the basin 

at that time, but their reservoirs apparently reduced the peak by 

a large amount. Diablo Reservoir stored about 26,000 cfs of the 

peak flow and Lake Shannon accounted for about 35,000 cfs which 

shows a total reduction of 61,000 cfs. This peak, also, could have 

produced disastrous results downstream under natural conditions.

The more recent floods have been quite small in comparison to the 

great floods of the past. Even though the present dams could con200

149,000 cfs estimated discharge 

147,000 cfs actual discharge

27 

FEBRUARY 1932

FIGFBE 4. Hydrographs showing effect of dams on flood peak.
DESCRIPTION OF FLOODS 17

ceivably reduce a great peak by many thousands of cubic feet per 

second, the total peak discharge of an extreme flood would be so 

great as to cause tremendous damage to the valley, especially to the 

area west of Sedro Woolley.

DIKES ON LOWER SKAGIT RIVER

Diking is knowc to have been practiced in the lower reaches of 

Skagit River in the early 1890's. In general, it was due to the efforts 

of individuals who were interested in keeping the summer floods 

away from their seeded farm land. Some areas near the river mouth 

were completely surrounded by dikes at an early date. In the 

beginning, the dikes were not very high but were raised to a sufficient 

elevation to confine minor floods to the river channel.

A map showing the locations of most of the major dike failures is 

shown as plate 2. Many breaks occurred downstream from Avon 

during the years 1894 and 1897.

In 1899 Sterling Dam was constructed at the head of Gages Slough 

which was a distributary of the Skagit River from the northern part 

of Sterling Bend. This was the commencement of major diking in 

the vicinity of Burlington and Sedro Woolley. Since that date, the 

entire river from near Burlington to Skagit Bay has been diked. 

These dikes have been strengthened almost continually and especially 

after each major flood.

During the February 1951 flood, the water surface was approximately at the top of the dike in two places near Burlington. Yet 

the peak discharge for this flood at the gaging station near Mount 

Vernon (at the highway bridge 1% miles north of town) was only 

144,000 cfs. This indicates the great possibility that future floods 

will breach these dikes and flood the lowlands. The dikes near the 

mouth did fail in several places in 1951.

The map of the lower reaches of Skagit River, plate 2, shows the 

location of most of the dike failures that have occurred during the 

last 73 years. From the location of these breaks, it is quite easy to 

determine approximately the areas that were inundated during each 

flood. The dike failures were not all detrimental to the landowners. 

Many dikes that normally protected low lying land along the shores 

of Puget Sound from salt water were breached to release Skagit 

River floodwater to Skagit and Padilla Bays, thereby preventing 

farmland from remaining submerged for a long period of time.

FLOOD PROFILE

Enough flood data are available to make a rough flood profile for 

the reach of channel from mile 7 to mile 21 (see log on page 6) and 

this profile can be extended to mile 50 (gage near Concrete).
18 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

10 15 20 25 30 35 40 45 

DISTANCE ALONG SKAGIT RIVER. !N MILES

FIGURE 5. Flood profiles.

Profiles for several floods are shown on figure 5. These profiles 

were obtained from the Corps of Engineers, U.S. Army, and are 

based on data obtained from the Great Northern Railway Company. 

A 1951 flood was confined by the dikes throughout this reach of 

channel, so below Sedro Woolley its profile is not parallel with the 

profile for the 1921 flood when the dikes in this area failed.

FLOOD PLAIN

A map showing the area that probably would be inundated by 

floods of the magnitude of those that occurred in 1815 and 1856 is 

shown on figure 6. Lesser floods would still cover a great part of 

this area as the flood of 1909 did inundate the greater part of it. 

This map was copied from a print of an old map obtained in 1945 

from the Skagit County Engineer. The source of the map is unknown 

but it has been checked and found to be quite accurate in detail.

FLOOD DAMAGE

Considerable damage results from the greater floods in the valley. 

The area upstream from Concrete sustains a comparatively small 

amount of damage and the greatest amount occurs downstream from 

Sedro Woolley.

The U.S. Army Corps of Engineers, summarized the total flood 

damage at about $4,850,000 for the floods of 1894, 1906, 1909, 

1917, 1921, and 1932. The two greatest losses were in 1894 and 1909
C

R. 3 E. R.4E. R. 5 E. R. 6 E. 

FIOUKE 6. Map showing area probably inundated b
20 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

with estimates of $1,500,000 for each flood. The average annual loss 

during the period 1894 to 1932 was $127,500. The above figures 

were obtained from House Document 187, 73d Congress (U.S. 

Congress, House of Representatives, 1933).

The damage from the flood of 1949 has been estimated as $587,000 

based on 1951 prices. It is interesting to note that the 1909 flood 

damage, based on 1951 prices, has been estimated as $6,600,000, or 

about 4 times the original figure. This shows that floods of great 

magnitude would now cause large monetary damage and have a 

serious effect on the economy of the valley.

HISTORY OF FLOODS

Settlers first arrived in Skagit Valley about 1878. At that tune 

they noticed that the bark on all of the larger fir and cedar trees, 

and on all of the spruce trees more than 1.5 feet in diameter was 

stained up to a certain height. The cause of this staining was the 

subject of much discussion until, in 1879, one of the oldest Sedro 

Woolley Indians described how the trees had been stained by an 

extremely high flood that occurred when he was a small boy. 1 The 

flood evidently made a deep impression upon him, because it came 

quickly and terribly one winter night. The flood probably caught 

the Indians asleep because in this old Indian's camp they barely 

escaped with their lives. They had no time to save their smoked 

salmon and dried venison. Apparently all the Indian camps along 

the river had the same experience because during that winter the 

Indians nearly starved. No doubt there was some loss of life, as 

there have been traditions handed down of drownings during the 

great flood.

From the estimated age of the Indian who remembered the flood, 

it was determined that this flood occurred between the years 1805 

and 1825. The middle year of the period, 1815, is used as a convenient 

designation in referring to this flood of Indian legend.

The stain on the bark of the fir and cedar trees was quite clear 

in 1878 but it dimmed rapidly, so that by 1900, it was no longer 

noticeable except on a very few trees. From the rapid dimming of 

the stains it appears that those visible in 1879 must have been caused 

by a flood more recent than "about 1815." During the flood of 

1909, Johnny Towne, an old Sauk Indian, told a white man that he 

had seen a much higher flood when he was a boy. In 1923 an Indian, 

thought to be 90 years old, told a Mr. James Cochraham that he 

remembered a flood several feet higher than the floods of 1909 and 

1921. He did not remember any flood that had drowned Indians,

1 Story was told to J. E. Stewart in June 1918 by Mr. Hart who lived on the right bank, between wagon 

and railroad bridges, in Sedro Wolley and had heard the Indian's story in 1879.
HISTORY OF FLOODS 21

although in his younger days he had known old Indians who 

remembered such a flood.

It would appear that a flood higher than that of 1909 had stained 

the fir and cedar trees prior to the coming of the white man but 

subsequent to the Indian legend flood of about 1815. Physical evidence of that flood was discovered in 1923 at The Dalles near Concrete. At that point there is a sandbar bench on the north side of 

the head of the canyon. The highest floods since the arrival of the 

white man have not covered this bar to a depth of more than two 

feet. On this bench were a number of young fir trees apparently 

all of the same age and much younger than the surrounding trees. 

A plausible explanation of this phenomena is that the bar was cleared 

of all trees during a large flood. In February 1923 one of the trees 

was cut down and found to have 62 rings at a stump height of 2.5 

feet. It was estimated that it would take four years for such a tree 

to attain a height of 2.5 feet, and the tree would have been 66 years 

old in 1922, the last year of its growth. The flood that cleared the 

trees from the bar could have occurred as late as 1857, allowing a 

year for error, but probably occurred earlier. It is assumed that this 

flood caused the stains on the trees noted by the settlers in 1878.

At Vancouver, Wash., precipitation records are available for the 

years 1849-68, 1888-92, and 1898 to date (1958). During these 80 

years of record the total monthly precipitation exceeded 10 inches 

only 19 times, and with one exception, it was always in either November, December, or January. Of these 19 months of high precipitation, 6 occurred in the 6-year period 1852-57 with the total precipitation for 2 consecutive months exceeding 20 inches 4 times during 

this period. Although there may be little direct relation between 

precipitation in the Skagit River basin and that at Vancouver, Wash., 

yet such unusually heavy precipitation at a point even that close lends 

support to the evidence of a large flood on the Skagit River "about 

1856."

From the description by early settlers, the flood of November 16, 

1896, was the highest that had occurred since the beginning of the 

settlement in 1878. The heights of the intermediate floods in the 

springs of 1880, 1882, and 1894 and the fall seasons of 1879, 1882, 

1883, and 1887 are known only within a foot or two and principally in 

relation to the flood of 1896.

The flood of November 19, 1897 was higher than the flood of 1896 

at all points. It was especially high in the reach from Cascade River 

to a short distance below Birdsview where, in general, it remains the 

highest flood since 1878.

The flood of November 16, 1906 is not well remembered although 

it severely damaged the draw span of the Great Northern Railway
22 FLOODS IN THE SKAOIT RIVEiR BASEST, WASHINGTON

bridge and destroyed one span of the highway bridge in Mount 

Vernon. It was on the latter bridge that a Mr. H. Peterson lost his 

life by running into the turning bar while trying to escape from the 

imperiled bridge. This flood was not so high as the flood of 1897 

except in certain districts on the delta where the confining effects of 

the dikes caused higher stages.

The flood of November 1909 was the largest flood on the Skagit 

River since the coming of the white man in 1878, except for the reach 

from Cascade River to a short distance below Birdsview where it was 

surpassed by the flood of November 1897. Higher stages may also 

have occurred at other points during other floods as a result of log jams.

Evidence indicates that the flood of December 30, 1917 was comparable to those of 1896 and 1906 with respect to crest height. The 

damage on the delta was largely the result of the sustained flood flows 

inundating large areas after the dikes had broken.

The flood of December 12, 1921 was nearly as great as the flood of 

1909 and was higher than that of 1917 except where some abnormal 

local condition prevailed.

It has been estimated that the natural discharge of the February 27, 

1932 flood near Concrete (corrected for effect of upstream storage) 

would have been about the same as the discharge of the floods of 1896 

and 1906 (U.S. Congress, 1933).

It has been estimated that the natural discharge of the November 27, 

1949 flood near Concrete (corrected for effect of upstream storage) 

would have been about the same as the discharge of the 1917 flood.

The flood of February 10, 1951 reached a stage at the gage near 

Concrete only 1.8 feet lower than the flood of 1949 and 6.7 feet lower 

than the flood of 1917.

The long period since 1921 without the occurrence of a destructive 

flood does not indicate that the chances of a devastating flood have 

decreased in any way. The size of floods to be expected in the future 

are discussed in sections on flood types and frequencies.

HISTORIC FLOOD DATA

The data for historic floods were taken directly from notes and 

statements of J. E. Stewart, the co-author of this publication. He 

spent considerable time in the field obtaining high-water marks and 

making studies of flood flows. Some of the statements in this section 

are similar to those made previously under the section on history, but 

they are repeated here in order to present the data on how the stages 

were obtained with other pertinent data concerning the floods.

Available data for the 1917 and 1921 floods are included in this 

section for comparative purposes.
HISTORY OF FLOODS 23

The gage heights for all floods at all stations are based on the maximum height reached by the surging water. This method became 

necessary because the height of all the earlier and some of the recent 

floods could be determined only in this manner. The resulting gage 

heights and discharges are somewhat greater than they would have 

been if the mean of the surges was used as is done at the present time. 

Data for several sites are given below.

Skagit River at Reflector Bar near Marblemount, Wash. 

[See gaging station 10, page 38.]

Date of flood

1815. ....... __ .. ....... _ ......

1856 . ...... . ... 

December 29, 1917 _________________

December 12, 1921. ______ . ________

Stewart's data

Elevation 

(feet)

20.5 

18.5 

12.5 

15.4 

12.5 

14.5

Discharge 

(cfs)

115, 000 

95,000 

48,000 

70,000 

43,000 

63,000

Gaging station data

Gage height 

(feet)

12.0 

14.1

Discharge 

(cfs)

37,300 

58,000

The flood dated 1815 probably occurred between 1805 and 1825. 

This is based on the age of an Indian interviewed in 1879 concerning 

that flood.

The flood dated 1856 did not occur after 1857 and probably not 

before 1850. This is known by precipitation data and by the age 

of trees on a bench that was cleared by this flood.

The stages of the 1815 and 1856 floods were determined near the 

gage from the elevation of Mgh-water marks on canyon walls and 

from flood sand deposited by those floods.

The stage of the 1909 flood was determined from drift and flood 

sand at, and upstream from, the gage.

Cascade River near Marblemount, Wash, 

[This site is about 6 miles upstream from Cascade Elver at Marblemount, gaging station 16, page 42.]

Discharge 

(cfs)

46, 000

40, 000

26, 000

32, 000

1815....__.___.__. 

1897___.-._._____. 

November 29, 1909. 

December 1917__.

Date offload

Elevation 

(feet)

22.0

20.0

15. 0

17.2

The 1909 flood peak was published in 1911 in Water-Supply Paper 

272 (Stevens and others) as 31,700 cfs.

Early settlers stated that the river was much higher in 1897 than 

it was in 1909; also, that it was much higher in 1917 than in 1909.

The Cascade Kiver emptied into the Skagit Kiver at a point upstream from its present confluence until during the 1897 flood when 

its course was changed to the present location.
24 FLOODS IN THE SKAGIT RIVEiR BASIN, WASHINGTON

Sank River at Darrington, Wash.

[Gaging station 19, page 44.]

Elevation Discharge 

Date offload (feet) (cfs)

1815__--__---____-____-_________________________ 18.0 48,000

1897___________._____.______________ 17.0 44,000

November 1909_____________________________ 16.0 40,000

December 29, 1917_._________________________ 15.0 36,000

Studies of river banks, including bars left from old channels, indicate 

that stages from 2 to 3 feet higher than 1917 have occurred. The 

flood of 1815 probably was not more than 1 foot higher than the 1897 

flood.

The flood of 1897 was higher than the 1909 flood on the Cascade 

Kiver to the north and the South Fork Skykomish River to the south, 

so it probably was higher on the Sauk.

The crest of the 1909 flood was obtained from a comparison by the 

gage observer of the relative stages of the 1909 and 1917 floods in 

his garden.

Baker River below Anderson Creek, near Concrete, Wash.

[Gaging station 22, page 47.]

Elevation Discharge 

Date offload (feet) (cfs)

1815__-_________-_____..___-_________________-__-__ 16.0 50,000

1897______________________________________________ 13.5 36,700

1909___-______-___________________________-____-_- 15.3 46,200

December 29, 1917______________________________ 13.7 36,800

December 12, 1921__________________________ 10.8 23,600

The great flood of 1815 probably reached a gage height of 16.0 feet.

The flood of 1897 probably was about the same height as the 1917 

flood, or possibly slightly lower.

The crest of the 1909 flood was obtained from drift marks on trees 

and from the high water beach line.

Skagit River near Concrete, Wash.

[Gaging station 25, page 50.]

Elevation Discharge 

Date offload (feet) (cfs)

1815__-____-_.__-_____-__________-_-._______ 56.6 500,000

1856________________________________ 44.6 350,000

November 19, 1897___-_________________-_------_-__ 38.4 275,000

November 30, 1909_________________________ 36.4 260,000

December 30, 1917_____________________________-_-._ 33.0 220,000

December 13, 1921__________________________.____-__ 34.9 240,000

The stage for the 1815 flood was determined from the maximum 

height of flood sand found just above The Dalles and about 300 feet 

upstream from the present gage.

The stage of the 1856 flood was determined from its high-water 

mark left on the canyon wall in The Dalles at the present gage site.

The floods of 1897 and 1917 have been dated on the assumption 

that the floods occurred shortly after midnight.
HISTORY OF FLOODS 25

The stages for the floods of 1897,1909, and 1917 have been estimated 

from flood marks about 1 mile upstream. The stage of the 1897 flood 

is not as certain as the stages for the other two floods.

Skagit River near Sedro Woolley, Wash.

[Gaging station 28, page 52.]

FUevation Discharge 

Date of flood (feet) (ds)

1815______________________________________________ 63.5 400,000

1856____________________________________ 60.0 300,000

November 16, 1896_________________________ 54.8 185,000

November 19, 1897_________________________________ 54.9 190,000

November 16, 1906__-----_-_-________________ 547 180,000

November 30, 1909-____.____________________ 56.5 220,000

December 30, 1917_________-__-__________________.__ 54.1 195,000

December 13, 1921...______________________ 54.3 210,000

The stage for the 1815 flood has been estimated from the height of 

the flood plain, from the stage and discharge at The Dalles, and by 

comparison with the stages of the 1856 and 1909 floods.

The stages of floods from 1815 to 1869, except that of 1856, are 

unknown. However, they were all of a lower crest stage than the 

flood of 1856. It is fairly certain, also, that the stages of any floods 

between 1856 and 1869 were lower than that of the 1909 flood.

There were no floods from 1869 to 1895 as great as those in 1896 

and 1906 according to statements of the early settlers.

The stage for the 1897 flood was determined from its relation to 

the 1896 flood about one quarter of a mile upstream.

The discharges for all floods except those in 1909, 1917, and 1921 

are, to a large extent, based on comparative stages and discharges at 

other points.

INDIAN LEGEND FLOOD OF ABOUT 1815

Reflector Bar (Diablo Dam). The stories which were told by the 

Indians support the evidence that the highest flood marks not 

associated with a more recent flood, and still visible when J. E. 

Stewart made his investigations over a hundred years later, were left 

by a flood that occurred "about 1815." Mr. Frank Davis found 

where sand had been deposited on the ground in a gulch near the 

present Diablo Dam at an elevation of 22 feet about the datum of the 

former gaging station at Reflector Bar. It was assumed from the 

nature of the deposit that the sediment had been left by the stream 

during a high flood. On the south side of Canyon Diablo opposite the 

gulch, J. E. Stewart found a dim mark on the canyon wall at an elevation of 21.3 feet that marked the height to which some flood had washed 

the rock clean. He also found deposits of flood sand in crevices of the 

rock wall at the mouth of Canyon Diablo as high as 20.8 feet, Reflector 

Bar gage datum, and a small piece of bark apparently left by a flood 

in a rock crevice nearly as high. A deposit of sand and gravel was
26 FLOODS IN THE SKAGIT RIVBR BASIN, WASHINGTON

found on the right bank at the upper end of Reflector Bar that 

probably had been left by the river during a flood. This deposit was 

of clean material devoid of leaves, dirt, logs, and humus when viewed 

by Stewart in 1918. The cleanness was considered an indication that 

the deposit was not much more than 100 years old. An excavation 

was made on the bar near the ranger station quite a long distance 

from the point where the river would overflow the bank. Alternate 

layers of sand and charcoal were revealed which showed that floods 

large enough to deposit sand on the bar that far back from the river 

had occurred several times previously. The charcoal found between 

the layers of sand probably was produced by forest fires.

The deposit of fresh sand was very coarse, almost small gravel, and 

extended about 600 feet back from the bank. For a flood to carry the 

sand that far, it would have had to overtop the bank by a least a foot. 

An estimation that the flood overtopped the bank by 1.5 feet gives a 

gage height of 19.5 feet. A gage height of about 20 feet for the flood 

was obtained by averaging the flood evidence at Reflector Bar and by 

taking the slope of the water surface into consideration.

Rockport. The magnitude of the 1815 flood is supported further by 

a legend among the Indians at Rockport that a number of their tribe 

were drowned on the bench where the Cuthbert ranch is located, during 

a great flood that occurred at night. This bench is at least 15 feet 

above the floodmark of 1917.

Concrete. At The Dalles, L. J. Wright, Assistant County Engineer 

of Skagit County, found deposits of flood sand on the ground in the 

small northside gulch which lies back of an old cabin at the head of 

the canyon. This deposit corresponds to a gage height of 69.3 feet 

present datum.

Sedro Woolley. Stewart estimated that this flood probably exceeded 

the flood of 1909 by about 7 feet and covered the highest ground in the 

town of Sedro Woolley with 1.5 feet of water. This would be equivalent to 10 feet of water in the present business district. Also, a stage 

of 63.5 feet (gage datum) is indicated for the 1815 flood.

TREE-STAININQ FLOOD OF ABOUT 1856

During his investigations in 1918, Stewart found that the marks of 

the 1856 flood were so easily and frequently found that its crest could 

be traced throughout the valley more easily than those of the floods of 

1896, 1897, and 1906. In most places it was marked only by sand in 

the deep crevices of the bark of old cedar trees. There was no mud in 

the bark of the fir trees, because of the rapid rate at which they shed 

their bark. The stains formerly in the bark of the cedar trees had 

apparently faded by weathering or had been dissipated by the growth 

of the trees.
HISTORY OF FLOODS 27

Reflector Bar. In 1923 near Reflector Bar, Stewart observed a 

deposit of fresh flood sand, 3.5 feet above the crest of the flood of 1909, 

that he believed indicated the crest of the flood of 1856. On that basis 

it was estimated that the flood reached a stage of 18.5 feet at the gage.

Concrete. On the north rock wall close to the mount of The Dalles 

near Concrete a distinct high-water line at a gage height of 57.3 feet 

(present datum) was visible in 1923.

Birdsview. Charles Presentine settled on his ranch above Birdsview in 1876. He found the ground surface, where his buildings now 

stand, underlain by very fresh-looking leaves and grass. The leaves 

and grass had been covered by sediment deposited by a flood that 

covered the flat to an unknown depth. The flat has not been overflowed since.

Mr. Kemmerick, an early settler, noted fresh flood sand inside hollow 

logs at his ranch below Birdsview. The logs were above any later 

floods. The fact that the logs were old and hollow when the sand was 

was deposited showed the flood to be recent; otherwise, the logs 

probably would have rotted away before Mr. Kemmerick saw them.

Sedro Woolley. In 1897 the stain marks of 1856 still could be found 

on the trees with little difficulty. The crest heights of the floods of 

1896 and 1897 were within 0.1 foot of each other. After one of those 

floods Mr. Hart 2 measured up from the high-water mark to the tree 

stains and found the distance to be exactly 4.0 feet. Mr. E. J. Woods, 

a former gage reader at the Northern Pacific Railway bridge, saw only 

one tree after the flood of 1909 with the crest mark of the old flood on 

it, and that was 3.5 feet higher than the 1909 floodmark. Later that 

tree was burned, but in January 1918 Stewart found an old cedar tree 

in which mud from the tree-staining flood was found in the bark 3.5 

feet above the 1909 floodmark. Both the latter trees were about two 

miles downstream from the Hart ranch at Sedro Woolley. As the 

gage height of the 1909 flood is 56.5 feet, the gage height of the 1856 

flood would be about 60 feet.

FLOODS OF 1880, 1882, AND 1894

The summer floods of 1880, 1882, and 1894 are remembered for the 

long periods during which the bottom lands around Mount Vernon 

were inundated.

FLOOD OF NOVEMBER 1897

This flood was the highest since the valley was settled in 1878. The 

river rose with remarkable suddenness, because a very warm chinook 

was accompanied by heavy rains. The Cascade, Sauk, and Baker 

Rivers were unusually high, which caused a high peak in the Skagit

* See footnote p. 20. . 

577864 ^1 3
28 FLOODS IN THE SKAGIT RIVEiR BASIN, WASHINGTON

River near the mouth of each stream. The chinook stopped suddenly 

after 36 hours; and, as a result, the peaks were rapidly reduced by 

channel storage as they passed down the Skagit River.

Reflector Bar. At Reflector Bar this flood was of about the same 

magnitude as that of 1917. Both floods put about one foot of water 

over the floor of an old cabin on the Davis ranch 1.5 miles below 

Reflector Bar.

Marblemount. Below Cascade River at Marblemount the flood of 

1897 was 1.3 and 2.2 feet higher than the floods of 1909 and 1917, 

respectively, as measured between high-water marks made by residents 

at Marblemount during each flood. The difference was caused by an 

enormous flood in Cascade River in 1897.

Rockport. The flood of 1897 is the highest ever observed by white 

men; however the amount by which it exceeded the floods of 1909 and 

1917 is unknown.

Concrete. Stewart found two floodmarks near Concrete for the 

flood of 1897. One, on a barn on the right bank about a mile upstream from Concrete, was transferred by levels to the footing of a 

hotel in Concrete on which the other floodmark had been made in 

1909. The difference between the two marks was 5 feet. After 

allowing 2 feet for the slope of the water surface, the flood of 1897 

was estimated to be 3 feet higher than the flood of 1909. Later, in 

1922, Stewart ran levels to a stump that a Mr. Magnus Miller stated 

was 1.5 feet out of water during the flood of 1897. From these levels 

the flood of 1897 was found to be 3.6 feet higher than the flood of 1909 

at Concrete.

The flood elevations in Concrete probably were affected to a considerable extent by the flow of Baker River. The relationship between the two floods at that point may have been quite different 

from the relationship at the gaging station site.

FLOOD OF NOVEMBER 1909

When Stewart made his investigations in 1918, the drift from the 

1909 flood still lay along the river and was but slightly rotted. Drift 

for a previous higher flood could not be found; this indicated that 

none had occurred within the period required for drift to decay and 

disintegrate, perhaps 50 years.

Reflector Bar. At Reflector Bar several distinct high-water marks 

were found by Stewart. One, on the front door of the Davis ranch 

house l)s miles below the gage, was found to be 2.4 feet higher than 

the crest elevation obtained for the 1897 and 1917 floods at a nearby 

cabin. This stage was confirmed by the high-water mud lines still 

visible in 1918 on the rock wall of Canyon Diablo 700 feet above the 

gage and by the height of a drift log 100 feet below the gage.
HISTORY OF FLOODS 29

Newhalem. The observer at the gaging station at Newhalem (near 

Marblemount) estimated the crest gage height the following morning 

from drift at the gage. This stage was checked in 1918 by Stewart 

using a hand level.

Concrete. In 1918 Stewart found many marks of the flood of 

1909 in and near Concrete. The footing of a hotel near the cement 

plant was just reached by the water. There were oil marks 4.5 feet 

above the floor on the outside galvanized siding of an old Washington 

Cement Plant shop building; these marks were referred to as being 

"as plain as though made yesterday."

FLOOD OF D1C1MBEB 1917

The flood of December 1917 was remarkable for the length of time 

it remained high, rather than for the height which it reached.

The gaging station at Reflector Bar was in operation; therefore, a 

good record of the flood was obtained at that point. As shown in 

the description of the flood of 1909, the crest was 2.5 feet below that 

of 1909.

FLOOD OF DECEMBER 1921

Gaging stations were in operation below Ruby Creek, at Reflector 

Bar, at Newhalem, and near Sedro Woolley at the time of the 1921 

flood. Gage heights for the flood at those places are part of the 

gaging-station records.

Concrete. Stewart made extensive studies of this flood at The 

Dalles near Concrete. He visited the place while the floodmarks still 

were so clear that the profile of the flood could be determined within 

one or two tenths of a foot. At The Dalles the Skagit River flows 

through a relatively narrow canyon for a short distance. Conditions 

there are fairly satisfactory for the computation of the peak flow by 

the contracted-opening method. Just below The Dalles is a straight 

reach of channel which is suitable for the computation of flow by the 

slope-area method. Stewart obtained the data for both types of 

measurements; the upper end of the rating curve for this gaging station is based on those computations.

FLOOD OF FEBRUARY 1932

The flood of February 1932 would probably have been much more 

serious if there had been no upstream storage. The storage probably 

reduced the peak by about 35,000 cfs at the gaging station near 

Concrete. In the lower reaches of the river, between Sedro Woolley 

and Mount Vernon, the dikes failed in two places and caused flooding 

of farm land and many homes. Also, several dike failures occurred 

along the distributaries near the mouth.
30 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

Two gages were in operation along the main stem during this flood 

and good records were obtained at these points. The gages were 

located at Newhalem and at The Dalles near Concrete. The crest 

at Newhalem, which was affected to some extent by storage, was only 

1.4 feet below that of the 1921 flood. The crest at the gage near 

Concrete has been listed as being 5.7 feet lower than that of the 1917 

flood, but again upstream storage was a factor.

FLOOD OF NOVEMBER 1949

The flood of November 1949 would probably have been among 

those causing considerable damage if there had been no upstream 

storage. The storage in the power reservoirs has been estimated to 

have reduced the crest at the gaging station near Concrete by about 

45,000 cfs. The peak near Concrete was of short duration, and there 

was only a moderate amount of inflow between Concrete and Mount 

Vernon. Channel storage reduced the peak in the lower reaches of 

the channel to a point where the diked channel was able to carry the 

peak flow without danger of a major dike failure. There were two 

minor breaks near the mouth.

Several gages were in operation along the main stem during this 

flood so good records were obtained at those points. Gages were in 

operation at Newhalem, at Marblemount, near Concrete, and near 

Mount Vernon. The crest near Concrete was 4.9 feet lower than 

that of the 1917 flood and 0.8 foot higher than the crest of the 1932 

flood.

Immediately following the 1949 flood, a slope-area reach was laid 

out and high-water and other field data obtained at the approximate 

site of J. E. Stewart's reach just below The Dalles near Concrete. 

These data were used to verify the value of the channel roughness 

coefficient, n, at this site for use in estimating the validity of the 

results obtained by Stewart.

FLOOD OF FEBRUARY 1951

The flood of February 1951 was almost as high as the flood of 1949 

at the gage near Concrete and was higher at the gage near Mount 

Vernon. The effect of upstream storage was much less for this flood 

than for some of the others and has been estimated to be about 13,000 

cfs for the peak at the gage near Concrete. However, this peak was 

of quite long duration and a large amount of inflow occurred between 

Concrete and Mount Vernon so that channel storage had very little 

effect in reducing the peak stage in the lower reaches of the channel. 

In at least two places between Sedro Woolley and Mount Vernon the 

river reached the top of the dike. In one place the dike sprung a
FLOOD RECORDS 31

leak, but this dike did not fail, and as a result there was only minor 

damage in that area. However, several dike failures occurred on the 

distributaries near the mouth, and considerable areas of land and 

many homes were inundated.

Several gages were in operation along the main stem of the river 

during this flood so good records were obtained at those points. 

Gages were in operation at Newhalem, above Alma Creek near Marblemount, at Marblemount, near Concrete, near Sedro Woolley (unpublished), and near Mount Vernon.

FLOOD RECORDS

Kecords of maximum flood stages and discharges that have been 

obtained at gaging stations operated in the Skagit River basin for 

five or more years are presented in the following tables. They are 

of two kinds: records of historic floods, based largely on the investigations of J. E. Stewart; and records obtained during the period of 

operation of the gaging stations, when continuous records were 

obtained.

The order of listing gaging-station records begins with the most 

upstream main-stem station, near Hope, British Columbia, and 

proceeds downstream along the main stem. All stations on a tributary 

entering above a main-stem station are listed before that station, and 

if a tributary enters between two main-stem stations, it is listed 

between them. The gaging stations are numbered in the above 

order and may be located by number on plate 1.

GAGING STATION RECORDS

The information on the following pages for each gaging station for 

which records are shown consists of a station description and a list 

of flood peaks.

The station description gives information as to location, drainage 

area, type of gage and elevation of gage datum, how well the stagedischarge relation is defined, remarks concerning effects of diversion 

and regulation, and other pertinent information.

Flood peaks listed for periods of gaging station operation are the 

maximum momentary peaks that occurred each water year, the year 

beginning October 1 and ending September 30. Also listed are stages 

and discharges for historical floods, including all those that occurred 

prior to time of beginning of systematic collection of data. A 

horizontal line across the year column indicates a break in the period 

of record and one across the gage height column indicates a change 

in datum.
32 FLOODS IN THE SKAGIT RIVEB BASIN, WASHINGTON

1. Skagit River near Hope, British Columbia, International gaging station

Location. Lat 49°02'50", long 121°05'45", on left bank just downstream from

Galena Creek, 4 miles upstream from the international boundary, and 27

miles southeast of Hope, British Columbia. 

Drainage area. 357 sq mi. 

Gage. Water-stage recorder. Altitude of gage is 1,670 ft (from topographic

map). Prior to October 1934, water-stage recorder at site 550 ft downstream

at different datum.

Stage-discharge relation. Defined by current-meter measurements below 6,500 cfs. 

Remarks. Records furnished by Canadian Department of Resources and

Development.

Annual peak stages and discharges of Skagit River near Hope, British Columbia

Water year

1915. 

1916 

1917 

1918 

1919 

1921 

1922 

1935 

1936 

1937 

1938

1939 

1940 

1941 

1942 . . ....

1943 

1944 

1945 

1946 

1947 

1948 

1949 

1950 

1951... 

1952 

1953 

1954.... 

1955 

Date

Apr. 4, 1915-.. 

June 17, 1916 _ . . .. 

May 29, 1917 ..... 

June 10, 1918 

May 26, 1919 

June 7, 1921 

Jan. 25, 1935 

May 31, 1936 

JuneS, 1937. __ - ___ _____________

May 26, 1938-. 

May 16, 1939 

May 24, 1940.. _ . 

May 2, 1941 

May 26, 1942 __ .... _

May 27, 1943 

May 29, 1944. - 

May 30, 1945. _ 

May27, 1946.. 

TVTflxr Q 104.7

May 28, 1948 

May 16, 1949 _ - 

June 21. 1950 

May 24, 1951 _ ... 

May 19, 1952 

June 13, 1953... 

May 19, 1954 

June 12, 1955 ______ . _ ----- _ . ____

Gage height 

(feet)

8.83

7.90

8.84

8.71

8.17

6.52

5.15

7.49

8.12

6.46

8.60

8.85

8.47

10.75

10.20

12.20

10.49

10.21

10.58

11.95

11.96

Discharge 

(ob)

U,280

17,560

15,920

15,980

15,140

16,920

16,850

6,560

5,070

6,570

6,370

5,440

2,990

1,560

4,440

5,420

2,510

5,560

5,960

5,630

9,720

6,850

10, 200

5,560

4,970

5,720

6,820

9,760

i Maximum dally.

2. Skagit River above Devils Creek, near Newhalem, Wash.

Location. Lat. 48°50'30", long 121°02'20", in W# sec. 30, T. 39 N., R. 14 E., 

on left bank 2 miles upstream from Devils Creek, 9}£ miles upstream from 

Ross Dam, and 15 miles northeast of Newhalem.

Drainage area. 650 sq mi, approximately, of which 400 sq mi is in Canada.

Gage. Water-stage recorder. Altitude of gage is 1,410 ft (from river-profile

map).

Stage-discharge relation. Defined by current-meter measurements below 6,600 cfs 

and extended by logarithmic plotting.
FLOOD RECORDS 33

Annual peak stages and discharges of Skagit River above Devils Creek, near Newhalem,

Wash.

Water year

1940 

1941...........................

1942. - -.-.-... _ _

1943_ 

1944..-.-.. ...............

1945. ....................

Date

May 24, 1940 

Oct. 21, 1940.... . . 

Dec. 3, 1941.. - .- _ - _

June 10, 1943 

May 16, 1944... __ .. 

May31, 1945 

Gage height 

(feet)

5.55

4.58

6.20

6.80

4.84

7.27

Discharge 

(cfs)

5,900

4,210

6,570

8,220

4,630

9,140

3. Beaver Creek near Newhalem, Wash.

Location.~La,t 48°46'40", long 121°04/20", in S}'2 sec. 14, T. 38 N., R. 13 E. 

(unsurveyed), on left bank three-quarters of a mile upstream from Ross 

Reservoir, 3 miles north of Ross Dam on Sakgit River, and 10}^ miles northeast of Newhalem.

Drainage area. 52 sq mi, approximately.

Gage. Water-stage recorder. Altitude of gage is 1,600 ft (from river-profile 

map).

Stage-discharge relation. Defined by current-meter measurements below 2,000 cfs 

and extended by logarithmic plotting.

Annual peak stages and discharges of Beaver Creek near Newhalem, Wash.

Water year

1940 

1941 

1942 

1943 

1944 

1<MS

1946 

1947 

1948 

Date

May 24, 1940 

Oct. 19, 1940 

Dec. 2, 1941.- 

July 4, 1943 

Dec. 3, 1943 . 

A/TO-IT 91 1Q4K

Oct. 26, 1945 

Oct. 25, 1946 

May 28, 1948 

Gage height 

(feet)

4.97

7.34

7.76

5.11 

4.63 

5.32

7.57

5.33

6.37

Discharge 

(cfs)

1,320

3,540

3,980

1,550 

1,280 

1,680

3,760

1,760

2,490

4. Skagit River near Newhalem, Wash. 

[Published as "above Ruby Creek, near Marblemount" 1930-31]

Location Lat 48°44'50//, long 121°01'50", in SK sec. 30, T. 38 N., R. 14 E.

(unsurveyed), on right bank 1% miles upstream from Ruby Creek and 11

miles northeast of Newhalem.

Drainage area. 765 sq mi, of which 400 sq mi is in Canada. 

Gage. Water-stage recorder. Altitude of gage is 1,250 ft (from river-profile

map). 

Stage-discharge relation. Defined by current-meter measurements below 13,000

cfs and extended by velocity-area studies.
34 FLOODS IN THE SKAGIT RIVEiB BASIN, WASHINGTON

Annual peak stages and discharges of Skagit River near Newhalem, Wash.

Water year

1922 

1930--- 

1931 

1932 

1933. . 

1934 

1935 - ..

1936 

1937 

1938 

1939 

Date

Dec. 12, 1921. .. __ . _ ___ . ___ 

June 11, 1930.. 

May 2, 1931 -

Feb. 27, 1932. 

June 16, 1933 

Apr. 24, 1934.. 

Nov. 5, 1934... 

May31, 1936. 

May 26, 1938 

May29, 1939 

Gage height 

(feet)

17.8

9.5

10.2

15.9 

13.1

12.0

13.05

11.11

11.39

11.74

11.13

Discharge 

(cfs)

33,000

8,270

9,860

25, 700 

17,300

14, 300

17,000

12,000

12, 700

13, 600

12, 100

5. Ruby Creek below Panther Creek, near Newhalem, Wash.

[Published as "Ruby Creek near Marblemount" prior to 1932 and as "Ruby Greek near Newhalem"

1932-49]

Location. Lat 48°42/30", long 120°58'10", in NW ft sec. 10, T. 37 N., R. 14 E. 

(unsurveyed), on right bank 200 ft downstream from Panther Creek, 4 miles 

upstream from mouth, and 13 miles northeast of Newhalem.

Drainage area. 199 sq mi. At sites prior to October 1948, 210 sq mi, approximately.

Gage. Water-stage recorder. Altitude of gage is 1,640 ft (by barometer). Prior 

to Mar. 8, 1940, water-stage recorder at site 3^ miles downstream and Mar. 

8, 1940, to Sept. 27, 1948 at site 2 miles downstream from present site, both 

at different datums.

Stage-discharge relation. Defined by current meter measurements below 5,600 cfs 

and extended by logarithmic plotting.

Annual peak stages and discharges of Ruby Creek below Panther Creek, near

Newhalem, Wash.

Water year

1929 

1930 

1931 

1932.. 

1933 

1934 _ 

1935 

1936 

1937 

1938 

1939 

1940 - - -

1941 

1942 

1943. .

1944 .

1945 

1946. 

1947 

1948 

1949 

1950 

1951 

1952. _ . _

1953 ___ - _ 

1954 _ 

1955 _

1956 

Date

May 14. 1931. --------- ____ - __ ..

Feb. 27, 1932.. 

June 14, 1933 

Apr. 23, 1934. 

Nov. 5, 1934 

May 25, 1938 

May 28, 1939. 

May 23, 1940 

Oct. 20, 1940 

A/TniT 94 1Q4.9

June 9, 1943 

May 15, 1944 

May 30, 1945 

May 26-27, 1946. 

May8, 1947 ... 

May 27, 1948 - 

May 15, 1949 

Nov. 29, 1949 

May23, 1951 . 

May 18, 1952 

June 13, 1953 

July 1, 1954.. 

July 16, 1955 

Oct. 25, 1955 

Gage height 

(feet)

12.57

12.10

12.47

14.15

14.09

13.74

13.92

13.51

13.12

13.08

6.91

5.S8

7.69

7.45

6.41

7.56

7.43

7.50

9.2

8.42

10.95 

7.50

6.38

7.16

7.82 

9.50

9.25

Discharge 

(cfs)

3,460

3,030

3,570

6,730

6,510

4,920 

3,460

4,850

4,480

4,530

4,650

3,070

1,630

4,650

4,160

2,370

4,360

4,160

4,260

9,920

5,170

8,640 

4,170

3,150

3,820

4,630 

6,540

6,240
FLOOD RECORDS 35

6. Skagit River below Ruby Creek, near Newhalem, Wash. 

[Published as "near Marblemount"]

Location. Lat 48°44'20", long 121°03'40", in SE# sec. 35, T. 38 N., R. 13 E.,

(unsurveyed), on right bank three-quarters of a mile downstream from Ruby

Creek and 9 miles northeast of Newhalem. 

Drainage area. 978 sq mi, of which 400 sq mi is in Canada. 

Gage. Water-stage recorder. Altitude of gage is 1,190 ft (from river-profile

map). 

Stage-discharge relation. Defined by current-meter measurements below 11,000

cfs and extended by reducing discharge at Reflector Bar by measured inflow.

Anmt/al peak stages and discharges of Skagit River below Ruby Creek, near 

Newhalem, Wash,

Water year

1920..........................

1921 

1922.............. ___ ......

1923 

1924. ... ..................

1925 .. . 

1926 ... __ ... . .-

1927 -... .... . 

1928 

1929 

1930 . ____

Date

July 1, 1920 ______ . ,.. __ . _____

June 7, 1921..... . ..... ............ ...... 

Dec. 12, 1921 __ ... _ .. ___ . _ ... ...........

Feb. 12, 1924.. 

May 19, 1925.... ........... _ . . .

Apr. 30, 1926.. 

May 22, 1928 _______ . ___ . _______ ..

May 23, 1929.. 

June 11, 1930 __ . ___ . _____ . ___ . ...

Gage height 

(feet)

9.39

11.95

16.1

10.75

12.2

11.6

7.76

11.35

11.4

9.65

8.9

Discharge 

(cfs)

12,600

25,200

45, 700

19,200

26,200

23,200

7,460

22,200

22,200

13,600

10,700

7. Ross Reservoir near Newhalem, Wash. 

[Published as "Ruby Reservoir" prior to 1945]

Location. Lat 48°44'00", long 121°04'10", in SE^ sec. 35, T. 38 N., R. 13 E., 

at Ross Dam on Skagit River, 1 mile downstream from Ruby Creek, and 9 

miles northeast of Newhalem.

Drainage area. 980 sq mi, approximately.

Gage. Water-stage recorder. Datum of gage is at mean sea level (city of Seattle 

benchmark). Prior to Sept. 24, 1940, staff gage, and Sept. 24, 1940, to June 

27, 1943, water-stage recorder at same site and datum. June 28, 1943, to 

Apr. 29, 1948, staff gage 500 ft upstream at same datum.

Remarks. Reservoir is formed by concrete arch dam completed to elevation 

1,615 ft in 1949; storage began Mar. 11, 1940. Capacity 1,202,920 acre-feet 

between elevations 1,250 ft (lowest outlet) and 1,582 ft (spillway crest).

Annual maximum elevation and storage of Ross Reservoir near Newhalem, Wash.

Water year

1941....... . . . ........

1942__ .............. .....

1943 ....................... .

1944..... ...............

1945.... __ ......... .........

1946 ___ ........ _ . -. -..

1947. 

1948... . _ . _ . ... 

1949 . ___ - 

1950 

1951.. . ___ .

1952 ......................

1953... .

1954.... .............. .... 

1955...... ................

1956... . .........

1957 . __ .... _ .

Date

July 19, 1941 ..

July 23, 1942 __

June 11, 1944 ....

July 31, 1945.. ...

May 27 1946

Aug. 3, 1947 

July 1, 1948.. _______ .... __ . _ . ____ - 

Aug. 5, 1949 _____ . _____ ... _ ... - . 

July 10, 1950 ___ _ _ 

July 27, 1951 

Aug. 11, 1952 ....

Aug 16 1953

Aug. 23, 1954... _____ . ____ .. . 

Aug. 15, 1955 - - -

Aug. 1, 1956 

Aug. 25, 1957 ....

Elevation 

(feet, m.s,l.)

1, 384. 6 

1, 384. 7 

1,384.05 

1,381.8 

1,384.0 

1, 415. 85 

1, 500. 90 

1, 562. 52 

1, 580. 13 

1, 582. 88 

1, 582. 37 

1, 582. 06 

1, 600. 00 

1, 600. 10 

1, 599. 86 

1. 600. 00 

1, 599. 91

Storage 

(acre-feet)

112,600 

113, 100 

111,800 

107,400 

111, 700 

182,800 

514, 490 

1, 004, 600 

1, 184, 000 

1,214,000 

1, 208, 000 

1, 205, 000 

1, 405, 300 

1, 406, 500 

1,404,100 

1,405,300 

1, 404, 100

577864 61-
36 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

8. Thunder Creek near Newhalem, Wash.

[Published as "near Marblemonnt" prior to 1931 and as "above Colonial Creek, near Marblemount"

in 1931]

Location. Lat 48°40'20"> long 121°04'20", in SE& sec. 23, T. 37 N., R. 13 E. 

(unsurveyed), on right bank half a mile upstream from Diablo Reservoir, 

8 miles east of Newhalem, and 20 miles northeast of Marblemount.

Drainage area. 98 sq mi, approximately. Ill sq mi at site prior to October 

1930.

Gage. Water-stage recorder. Altitude of gage is 1,220 ft (from river-profile 

map). Prior to October 1930, water-stage recorder at site 3 miles downstream at different datum.

Stage-discharge relation. Defined by current-meter measurements below 2,900 

cfs and extended by logarithmic plotting.

Remarks. Discharges for period 1920-30 at lower site were adjusted to upper 

site by 0.8 power of ratio of drainage areas.

Annual peak stages and discharges of Thunder Creek near Newhalem, Wash.

Water year

1920 

1921. _ . _____ 

1922.... __ . _ 

1923 

1924. ___ ... _ ..

1925 

1926... ___ _____ 

1927... _ .. __ ..

1928 

1929... _ _ . ____ 

1930..... _ . _ - __ .

1931 

1932... ___ 

1933.-. . _ _ 

1934..... _ .. _______ . _ .

1935 . _____ _ - _

1936.... 

1937 

1938 

1939.... ___ .. - . 

1940.. _ .. _ . __

1941 _____ . __ . ____ . ....

1942 

1043

1944 .. __ ... _ .....

1945.... ___ _____ . __ 

1946. _____________ 

1947.. _ - _ . ________ 

1948 

1949 __ - _____ - ___ -

1950... __ . _ - ___ 

1951 __ _ - __ - .......

1952 

1953.. .

1954 

1955 . _ . _____ . _ .. ....

1956 

1957 

Date

Sept. 11, 1920. 

June 7, 1921-. ___ . ... _ _ .

Dec. 12, 1921.. _ ...

June 9, 1923. 

Feb. 12, 1924... _ .... _ ....... ___ ...

Dec. 12, 1924. 

July 5, 1926 

Oct. 16, 1926 __ ..... ____ .... ____ -

May 22, 1928 - __ - _ - _ - 

Oct. 9, 1928 _ ..... - -...-. 

July 13, 1930... _ ...... ___ .

June 26, 1931.. ___ _ ... ....

Feb. 26, 1932 __ .... __ ...... _ . ___ ..

Nov. 13, 1932 __ .... ___ .. _ . . 

July 16, 1934... ......................... ....

Nov. 5, 1934.. ________ ...... .. 

May 30, 1936 __ . _ ... .....

June 21, 1937. - _ . ...... ...

Oct. 28, 1937 

May 28, 1939 ____ ................ ___ ~

May 23, 1940 _ .... .... ........ ...

Oct. 20, 1940.. ____ ..... _ . _ .

Oct. 3, 1941 ____ ..... . . 

July 10, 1943.... - ...... .... ... ....

Sept. 20, 1944.. . __ .... ____ 

Sept. 4, 1945... . - ...... 

Oct. 25, 1945 __ . _____ . _ ... . 

Oct. 25, 1946... ____ . ____ 

Oct. 19, 1947...- _ 

May 13, 1949 _______ . ___ .... _ 

Nov. 27, 1949. _____ _ .. 

Feb. 10, 1951 ____ .... _____ ... . . _ .

June 4, 1952 _ ... ... . ... -

Sept. 28, 1953.. __ . __ . _____ - _______ .

Aug. 23, 1954 _______ ........ ... ...... ....

July 16, 1955. . .. . . .....

June 11, 1957.. -

Gage height 

(feet)

8.2

11.3

9.27 

8.82

10.0

8.30

7.34

11.0

9.14

6.63

9.56

8.15 

7.10

7.43 

7.67 

8.68 

9.74

8.90 

7.06

12.14 

8.54 

7.02

7.14

7.48

7.80

12.68

7.38

Discharge 

(cfs)

4,490

4,140

13,900

2,880

5,760

3,800

2,420

9,410

3,280

7,960

2,420

3,630

8,160

5,010 

4,440

6,120

3,800

2,650

7,630

4,740

2,060

5,430

3,530 

2,300

2,780 

3,080 

4,220 

5,550

4,410 

2,560

9,630 

3,870 

2,580

2,690

2,850

3,170

10,800

2,790
ELOOD RECORDS 37

9. Diablo Reservoir near Newhalem, Wash.

Location Lat 48°43'00", long 121 WOO", in SE^ sec. 5, T. 37 N., R. 13 E. 

(unsurveyed), at Diablo Dam on Skagit River, 1 mile downstream from 

Thunder Creek, and 6 miles northeast of Newhalem.

Drainage area. 1,100 sq mi, approximately.

Gage. Water-stage recorder. Datum of gage is at mean sea level, (City of Seattle 

bench mark). Prior to Oct. 12, 1931, staff gage at approximately same site 

and datum.

Remarks. Reservoir is formed by concrete dam, completed in 1930; storage 

began in October 1929. Usable capacity, 76,220 acre-feet between elevations 

1,040 ft (bottom of outlet pipes) and 1,205 ft (top of taintor gates). Crest 

of spillway is at elevation 1,187 ft. Maximum contents prior to 1943 from 

capacity table dated Oct. 10, 1930; maximum content on July 14, 1933 from 

table used subsequent to 1943 is 90,600 acre-feet.

Annual maximum elevation and storage of Diablo Reservoir near Newhalem, Wash.

Water year

1932 

1833... __ . ___ 

1934.. 

1935........-. _. . . .

1936...... _ ........ __ .. ...

1937... ___ .... _ ... ........

1938 

1939... _ ..... __ ..... ... _ .

1940...... ______ ..........

1941.... _______ ... . _ ...

1942..... ........ .........

1943 

1944....... _____ .. __ ....

1945.... _____ . _ . ____ ..

1946.. ...... ...........

1947 ........ ................

1948.. ____________ .

1949 

1950...... 

19fil _ 

1952..... ______ .... ........

1963 ........

1954 ....... ................

1965.. __ . ....

1956... _ . ________ ......

1957... _ .... _______ . _ .

Date

July 10, 1932 

July 14, 1933. ... .......................

July 16, 1934 __ ... ___ ........ _ . ...

July 24, 1935 __ . _ ....... ___ . _ . _ ...

Sept. 1, 1936.. ___ ... .... ... _ . _ ....... _ ..

Sept. 6, 1937 

July 27, 1938 - ___ - _ - _ . _ ___ . _

Jan. 1, 1939. . 

Sept. 1, 1940. ____ ..... ....... . _ 

Oof- in icun

July 13, 1942 __ . _ ..... .... _ .......... ...

Sept. 18, 1943.. __ . __ ... ____ .... .. 

(i) __ _ . .. . ..... . ..

Aug. 28, 1945 (')

May 7, 1947 ____ .... .. _ .

May 22, 1948 

Oct. 7, 1948.. . 

Nov. 28, 1949... _____ . _ ....... __ ... .. ....

Sept. 18,28, 1951 _ 

Aug. 1, 1952 

Nov. 17, 1952 ____ . _____ ... _ . ___ . _ .

July 23, 1954. __________ .... ___

Mar. 24, 1955- ________ .... . _ ... _ 

Oct. 25, 1955... _ . ________ .......

Aug. 18, 1957 

Elevation 

(feet, m.s.l.)

1, 205. 76

1,206.5

1,206.02

1, 206. 08

1,206.20

1,206.00

1, 206. 30

1, 206. 17

1,206.16

1, 206. 01

1, 206. 2

1, 205. 9

1, 206. 0

1,205.1

1, 206. 0

1,206.0

1,206.18

1,206.1

1, 198. 2

1,205.0 

1, 205. 9

1, 205. 6

1,206.0

1, 205. 89

1,206.17

1,205.85

Storage 

(acre-feet)

92, 010

92,720

92,260

92,230

92,430

92,240

92,520

92,400

92,390

09 14/1

09 43(1

90,050

90,140

89,310

90,140

90,140

90,310

90,230

83,200

89,220 

90,050

89,770

on i<m

90,040

90,300

90,000

i Oct. 2 and Dec. 14,1943, Mar. 16,27, July 26, and Aug. 3,7,24,1944. 

» May 22 and June 14,1946.
38 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

10. Skagit River at Reflector Bar, near Newhalem, Wash. 

[Published as "near Marhlemount" 1913-22]

Location.^-L&t 48°42'50", long 121°08'30", in N# sec. 8, T. 37 N., R. 13 E. 

(unsurveyed), on right bank just downstream from Canyon Diablo, a quarter 

of a mile downstream from later site of Diablo Dam, three-quarters of a mile 

upstream from Stetattle Creek, \% miles downstream from Thunder Creek, 

6 miles northeast of Newhalem, and 19 miles northeast of Marblemount.

Drainage area.' 1,100 sq mi, approximately, of which 400 sq mi is in Canada.

Gage.' Water-stage recorder. Altitude of gage is 880 ft (from river-profile map). 

Dec. 6, 1913 to Apr. 13, 1914, staff gage at same site and datum.

Stage-discharge relation. Defined by current-meter measurements below 24,000 

cfs and extended by logarithmic plotting.

Annual peak stages and discharges of Skagit River at Reflector Bar, near Newhakm,

Wash.

Water year

1815 . _ . _________

1856 

1898... ........................ 

1910-. ............. ........

1914... .....................

1915... _ . _______ . .......

1916... ___________ . ....

1917.. 

1918... _____________ . 

1919....... ....................

1920... .......... .............. 

1921... _____ . ..............

1922... ........................

Date

Nov. 18, 1897 

Nov. 29, 1909. . ___ .... - - ...

Jan. 6, 1914.. ___ _..__....._. . . ..

Apr. 3, 1915 _______ . ...

June 17, 1916 ______ . _ . _______ ... ....

June 16, 1917... ________ ........ ...

Dec. 29, 1917. _ . ____ . 

May 27, 1919 ______________ - __ - 

July 1, 1920.... __ .... ____ .. _ ..... .. .... 

June 7, 1921 _ . ___ ...... - .....

Dec. 12, 1921-. ________ - _ 

Gage height 

(feet)

20.5

18.5

12.5 

15.4

7.8

6.52

10.5

8.19

12.0 

9.0

7.0 

10.7

14.1

Discharge 

(cfs)

115,000

95,000

48,000 

70,000

16,800

11,800

29,400

19, 700

37,300 

24,200

15,600 

30,800

58,000
FLOOD EECORDS 39

11. Stetattle Creek near Newhalem, Wash. 

[Published as "near Marblemount" 1913-15]

Location. Lat 48°43'30", long 121°09'20", in NE^ sec. 6, T. 37 N., R. 13 E., 

on left bank three-quarters of a mile upstream from mouth, 5% miles northeast 

of Newhalem, and 18^ miles northeast of Marblemount.

Drainage area. 21.4 sq mi.

Gage. Water-stage recorder Altitude of gage is 925 ft (by barometer). Sept. 7, 

1933, to Aug. 26, 1937, water-stage recorder 150 ft upstream at datum 1.69 ft 

higher.

Stage-discharge relation. Defined by current-meter measurements below 1,500 

cfs and extended on basis of slope-area determination of the Nov. 26, 1949 

flood peak.

Annual peak stages and discharges of Stetattle Creek near Newhalem, Wash.

Water year

1934.. 

1935.. ____ 

1936. . -_. . .. .-- 

1937.. ... ..................

1938... _- _-.-..._. 

1939. - .._..._ _-.. 

1940. ___ . _ . __ . _____ .

1941 __ .......................

1942 __ .......................

1943.... - .--......_.. 

1944.. ..................... ...

1945 __ . ______ . ..........

1946.. ........................

1947. ____ . ____ . __ . ...

1948.. ...... .................. 

1949 __ .......................

1950. ____ . __ .. _ . _ ..

1951..........................

1952..... ._..._._.. ..

1953 _________ ... ........

1954. .........................

1955..........................

1956 __- .._._..... .-

1957. .........................

Date

Oct. 23, 1933....................................

Nov. 5, 1934.. 

.Tiinfi 2, 1Q3fi

June 18, 1937 _ ...... ................. ....... 

Oct. 28, 1937 

May 28, 1939.. ...... .. ..

Nov. 30, 1939.. .

Oct. 19, 1940. _______ . ____ . ____ . __

Dec. 2, 1941 ________ _..... _ . ............

June 17, 1943 ___ . ____ ... .. ...............

Dec. 3, 1943..-. . . .. .

Feb. 7, 1945...................... ...............

Oct. 25, 1945 _________ . ....................

Oct. 24, 1946... ...........................

Oct. 19, 1947.. ...... . 

Oct. 6, 1948... ............................. 

Nov. 26, 1949.. 

Feb. 10, 1951 ___________ . ____ . ....

Sept. 30, 1953.. ....................... .......

Oct. 30, 1953......... ......... ..................

Nov. 22, 1954 ___ . _________ ..... _ . ....

Oct. 25, 1955.. ..................................

Oct. 21, 1956.. ...............................

Gage height 

(feet)

7.17

10.4

4.78

5.50

7.34

6.64

5.10

6.03

6.77

4.70

5.62

6.10

7.16

5.85

6.80 

5.87 

9.70

4.76

5.20

5.08

4.88

7.34

5.08

Discharge 

(cfs)

2,020

5,640

1,010

1,370

3,220

2,560

1,130

1,940

2,680

870

1,510

1,980

3,210

1,740

2,730 

1,740 

8,580

13,300

1,480

1,820

1,710

1,540

4,330

1,710

1 Estimated.
40 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

IS. Skagit River at Newhalem, Wash. 

[Published as "near Marblemount" 1909-14,1921-31]

Location. Lat 48°40'20", long 121°14'45", in SE# sec. 21, T. 37 N., R. 12 E., 

on right bank a quarter of a mile upstream from Newhalem Creek, half 

a mile downstream from city of Seattle powerplant at Newhalem, 11 miles 

upstream from Bacon Creek, and 13 miles northeast of Marblemount.

Drainage area. 1,160 sq mi, approximately, of which 400 sq mi is in Canada.

Gage. Water-stage recorder. Datum of gage is 401.5 ft above mean sea level 

(river-profile survey). Dec. 21, 1908, to May 23, 1914, staff gages half 

a mile upstream at datum 91 ft higher, Nov. 15, 1920, to June 4, 1923, staff 

gage 500 ft upstream at present datum.

Stage-discharge relation. Defined by current-meter measurements below 26,500 

cfs.

Remarks. Flow partly regulated by Gorge Dam since August 1924, by Diablo 

Reservoir since October 1929, and by Ross Reservoir since March 1940.

Annual peak stages and discharges of Skagit River at Newhalem, Wash.

Water year

1815................... _ ....

1856. .........................

1898..........................

1909. - 

1910. _ ..- _. .

1911.. - .- . __ ....

1912-- .............. __ ...

1913. ... ............. ....

1914.. .............. _ .......

1918..- ...-. .-.-.......

1921.- 

1922.. ... .. ................ 

1923.. .............. ......

1924.. ... . . _ ....

1925-- 

1926. _ . ......

1927-. ..................

1928. - - .

1929-- 

1930. 

1931.... ......

1932.. ........... _ ....... 

1933.- _

1934. 

1935. ..... ... .....

1936.- .................. ...

1937.. _ ......

1938. . 

1939-. 

1940-- 

1941..........................

1942.. .....................

1943-- 

1944... ..................

1945.. ...................

1946. - .-

1947-- __ .... ....

1948. . ........

1949-- .

1950... ... __ ..

1951.. . ..- 

1952...... .................... 

1953.. ...................

1954.. ..................

1955.- _. .

1966.. ............... __ .

1957. . .... .

Date

Nov. 19, 1897 

June 2, 1909. __ .... _____ . _ ... . 

Nov. 29, 1909 

June 14, 1911.. _ . _ - ___

May 15, 1912 ____ ....... _ .. _ ...... __

Jan. 6, 1914.. ....

Dec. 29, 1917 

Dec. 12, 1921. __ _.._ - 

Feb. 12, 1924...... _. 

May 20, 1925 __ 

Apr. 30, 1926 __ ...... __ 

June 8, 1927- _ 

Oct. 9, 1928.. ..... ..... . 

June 11, 1930. _ .. ..... 

May 2, 1931. 

Feb. 27, 1932-..- ... ... 

June 15, 1933.. -

Apr. 23, 1934. ..... ..... ... _

Jan. 25, 1935 

May 31, 1936.. .. _

June 3, 1937 ... 

Oct. 28, 1937. . 

May 29, 1939 

May23, 1940. ... -

Ont 9fl 1Q4fl

May 26, 1942.. ... 

May 27, 1943 

May 31, 1945. _ . _ .-

May 27, 1946. 

May 25, 1947 

June 15, 1948------ ________ __ -

May 15, 1949 

Dec. 24, 1950-- . 

Oct. 29, 1951. . . 

July 14, 1953.- .... ...... . . 

July 3, 1954... .. _ 

July 16, 1955.... 

Oct. 25, 1955-- 

June 7. 1957. __ 

Gage height 

(feet)

20.5

18.5

12.5

12.3

22.0 

11.9

10.2

12.6

10.5

19.0

91.1

94.8 

89.14

90.85

89.65

85.68

89.56

89.75

89.15

86.90

87.53

92.84 

90.15

89.64 

90.82

89.27

89.32

89.69

89.3

87.56

88.12

88.14

88.82

86.45

88.89

89.73

87.11

87.53

86.59

88.20

88.33 

86.64 

88.66

88.40

88.75

88.14

86.30

Discharge 

(cfs)

115,000

95,000

48,000

26,900

63,500 

25,500

19,800

27,900

20,700

47,400

31,400

60,000 

21,400

31,400

25,400

9,220

26,000

27,200

23.600

13,400

15,500

45,000 

28,200

25,000 

30, 300

22,400

22,500

24,400

22,400

15, 100

17, 100

17,400

20,400

11,200

20,700

24,400

13,500

15,100

11,800

17,700

18,300 

12,000 

19,700

18,600

20,100

17,500

10,900
FLOOD RECORDS 41

13. Skagit River above Alma Creek, near Marblemount, Wash.

Location. Lat 48°36'25", long 121 °21'35", in NEK sec. 15, T. 36 N., R. 11 E.,

on right bank three-quarters of a mile upstream from Alma Creek and 7

miles north of Marblemount.

Drainage area. 1,260 sq mi, approximately, of which 400 sq mi is in Canada. 

Gage. Water-stage recorder. Datum of gage is 358.8 ft above mean sea level

(from river-profile survey). 

Stage-discharge relation. Defined by current-meter measurements below 21,000

cfs and extended by logarithmic plotting. 

Remarks. Flow partly regulated by powerplants on upper Skagit River, and by

Ross and Diablo Reservoirs.

Annual peak stages and discharges of Skagit River above Alma Creek, near

Marblemount, Wash.

Water year

1951...... . ___ ...

1952.............. _ ..........

1953........... ................

1954.. _ ................... _

1955...................... _ ..

1956... _ ............. ____ .

1957... . 

Date

Feb. 10, 1951........................... .........

Oct. 29, 1951.................... _ ..............

July 14, 1953.. 

July 3, 1954.-...........-.......-. .......... ..

July 16, 1955.... _ ..... _ ......................

Oct. 25, 1955.... .................................

Oct. 17, 1956........ _ . _ . _ ..................

Qage height 

(feet)

14.40

10.26

12.44

12.24

13.44

14.64

11.37

Discharge 

(cfs)

28,000

12,900

20,200

19,400

24,200

29,400

16,800

14. Bacon Creek near Marblemount, Wash.

Location. Lat 48°35'20", long 121°23'40", on line between sees. 20 and 21, 

T. 36 N., R. 11 E., on highway bridge near right bank a quarter of a mile 

upstream from mouth and 4J^ miles north of Marblemount

Drainage area. 50.9 sq mi.

Gage. Wire-weight gage read twice daily. Gage heights are from graphs based 

on gage readings, except that for the 1950 water year, which is from a 

high water mark. Altitude of gage is 350 ft (from river-profile map).

Stage-discharge relation. Defined by current-meter measurements below 2,000 

cfs and extended on basis of slope-area determination of the Nov. 26, 1949 

flood peak.

Annual peak stages and discharges of Bacon Creek near Marblemount, Wash.

Water year

1944..... ...................

1945... .....................

1946 .....................

1947 

1948... . _ ............ 

1949 - . - ...

1950 

Date

Dec. 3, 1943.. 

Feb. 7, 1945.....

Oct. 25, 1945 

Oct 24, 1946

Oct. 19, 1947. . _ 

Oct. 7, 1948

Nov. 26, 1949 

Qage height 

(feet)

4.25 

5.62 

6.20 

5.88 

5.67 

4.65 

7.13

Discharge 

(cfs)

3,050 

5,510 

7,000 

6,480 

5,670 

3,300 

18, 100
42 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

15. Skagit River at Marblemount, Wash.

Location. Lat 48°32'00", long 121°25'40", in NWK sec. 7, T. 35 N., R. 11 E.,

on right bank half a mile north of Marblemount and 0.6 mile upstream from

Cascade River.

Drainage area. 1,360 sq mi, approximately, of which 400 sq mi is in Canada. 

Gage. Water-stage recorder. Datum of gage is 305.1 ft above mean sea level

(river-profile survey). 

Stage-discharge relation. Defined by current-meter measurements below 20,000

cfs and extended by logarithmic plotting. 

Remarks. Flow partly regulated by powerplants on upper Skagit River, and by

Diablo and Ross Reservoirs.

Annual peak stages and discharges of Skagit River at Marblemount, Wash.

Water year

1944... ______ . ______

1947 ............. ...........

1948...... ..................

1949 .. 

1950.. 

1951...........................

1952...........................

1953...........................

1954.... ______________ .

1955...........................

1956... ____ . ____ .... ....

1957... .- 

Date

Oct. 25, 1946..... ____ . ____ ... __ . __ .

Oct. 19, 1947... - ________ .... _ - _

May 12, 1949 __ . __ ...... _ ............ __

Nov. 27, 1949. __ . ____ ...... __ . ... .... 

Feb. 10, 1951... _ _ 

Oct. 29, 1951.. _ . ___________ .... _ . ....

July 14, 1953.. _____ . _ ... ___ .

July 4, 1954... _ ._....__ 

July 16, 1955.... __ . ___ . ____ ..... ____ .

Oct. 25, 1955.. ___ . _ ..... __ ....... __ ...

Oct. 17, 1956.... . ___ ..

Gage height 

(feet)

5.66

6.98

8.52

5.90

11.37 

9.65

5.40

6.64

6.69

7.37

9.25

7.01

Discharge 

(cfs)

16,800

24,600

35,400

17,900

59,300 

42,400

14,000

20,500

21,100

25,600

38,900

23,000

16. Cascade River at Marblemount, Wash. 

[Published as "near Marblemount" 1909-12]

Location Lat 48°31'25", long 121°23W, in N# sec. 16, T. 35 N., R. 11 E.,

on right bank \% miles downstream from Boulder Creek, 2 miles east of

Marblemount, and 2% miles upstream from mouth.

Drainage area. 171 sq mi. 140 sq mi, approximately, at site prior to May 1,1913. 

Gage. Water-stage recorder. Datum of gage is 380.3 ft above mean sea level

(river-profile survey). April 1909 to May 1, 1913, staff gages at site 5%

miles upstream from present site at different datums. 

Stage-discharge relation. Defined by current-meter measurements below 5,000

cfs and extended by logarithmic plotting. 

Remarks. Discharges for period 1909-12 at upper site were adjusted to lower

site by 0.8 power of ratio of drainage areas.
FLOOD RECORDS 43 

Annual peak stages and discharges of Cascade River at Marblemount, Wash.

Water year

1815...........................

1898........................... 

1010................. _____

1911.. . - .--.-.._ _ ..

1912...........................

1918... .- ....__._._..

1929...........................

1930 ___ ............. ____

1931.. _______ ... __ . ....

1932...........................

1933... ___ . ____ . .........

1934...........................

1935...... _ .. _ ........ .....

1936...........................

1937...........................

1938. ___ . ____ . ___ ...

1939...........................

1940..... ...................

1941..... ______ .... ......

1942....... __ . __ .. ___ ..

1943... ____ .... _ . ____ .

1944... __ . ____...... ...

1945 ___ .... ____ ..........

1946...........................

1947... __ .... . __ . __ .....

1948... __ .... _ ........ __ .

1949.. ___ . __ ...... .......

1950.. .................

1951... ___ ..... _ .... ......

1952...........................

1953.......... _ ......... __ .

1954.. ___ ....... ___ ... _ .

1955....... ........ .........

1956..... ______ ....... .

1957...........................

Date

Nov. 19, 1897 _____ . ___ . __ . __ . __ . 

Nov. 29, 1909 ___ . __ .... _ . ___ - ......

Oct. 10, 1910 - - ._ .. ..

Dec. 29, 1917 __ . _ - _____ . ______ - ....

Oct. 9, 1928.. _____ . __ .... _ . __

Jan. 27, 1931.. __ ....... __ . _ . __ .... _ ..

Feb. 26, 1932 __ . ____ . _______ . _ ....

Nov. 13, 1932 _________ . _ . ___ ... .....

Nov. 2, 1933.... ___________ . __ .. __ ..

Nov. 5, 1934 .. ________ ... __ ..... .....

June 2, 1936 __ .. _ __ .... ....

Oct. 28, 1937... __ . __ . ___ . _ ..... ___ .

May 28, 1939... ______ _ - ____ .....

Dec. 15, 1939 _____ ... __ . _ . _ ....... ...

Oct. 19, 1940 _ .

T)«rt o 1 Q4. t

Jan. 7, 1945.. .. ..

Oct. 25, 1945 ___ . ____ ........ __ .... ......

Oct. 25, 1946.. __ . __ ... ....... ... . ___ . ...

Oct. 19, 1947 .. .. __ . _ . _ . ____ ....

May 13, 1949. 

Nov. 27, 1949 _ .... __ . _ . __ .... __ ..

Feb. 10, 1951 ___ .... _____ . __ .. ___ ...

June 4, 1952 _____________________

Jan. 31, 1053 _____________________

Aug. 23, 1954 __ . _____ . __ ..... _ ........

June 10, 1955 __ . ___ .. _ . _ .... __ . ......

Oct. 25, 1955 _ . ____ . ___ . _ . _ ...... ....

Oct. 17, 1956.. __ . ___ . _________ . _ 

Gage height 

(feet)

22.0

20.0

17.2

9.20

5.43

6.55

9.88

9.02 

8.06

9.40

7.07

6.59

8.62

8.19

5.87

6.58

7.66

6.26

6.98

6.62

8.84

9.54

9.33

7.14

11.47

8.89

6.43

6.70

7.09

7.49

9.31

6.66

Discharge 

(cfs)

46,000

40,000 

26,000

17,300

8,200

32,000

10,700

2,740

4,480

12,900

10,400 

8,050

11,500

5,760

4,760

8,810

7,870

3,190

4,430

6,730

3,820

5,210

4,430

9,620

11,600

11,000

6,420

17,800

9,650

4,280

4,750

5,470

6,270

10,800

4,630

17. South Fork Sauk River near Barlow Pass, Wash.

Location. Lat 48°03'45ff, long 121°24'20", in NE& sec. 29, T. 30 N., R. 11 E.

(unsurveyed), 2% miles upstream from North Fork, 3J^ miles northeast of

Barlow Pass, and 16 miles southeast of Darrington. 

Drainage area. 32.7 sq mi. 

Gage. Water-stage recorder. Altitude of gage is 1,550 ft (from river-profile

map). 

Stage-discharge relation. Defined by current-meter measurements below 1,400

cfs and extended by logarithmic plotting.

Annual peak stages and discharges of South Fork Sauk River near Barlow Pass,

Wash.

Water year

1918.. ... 

1919. .

1920 . 

1922 __ . _ ... _ .. ____ ....

1929..... ......................

1930...........................

1931 . . .. 

Date

Dec. 29, 1917 ....

Nov. 15, 1919 ....

Dec. 12, 1921....

June 15, 1929 ....

Feb 5 1930

Jan. 27, 1931 ____ .. __ _ .. _

Gage height 

(feet)

9.1 

6.3

7.7

9.5

5.37 

6.37

7.22

Discharge 

(cfs)

9,410 

3,350

5,870

10,500

1,100 

2,080 

3,210
44 FLOODS IN THE SKAGIT RIVE.R BASIN, WASHINGTON

18. Sank River above Whitechuck River, near Darrincton, Wash.

Location. Lat 48°10'00", long 121°27'45", in NW>4 sec. 24, T. 31 N., R. 10 E.,

on right bank half a mile upstream from Whitechuck River and 9Ji miles

southeast of Darrington. 

Drainage area. 152 sq mi.

Gage. Water-stage recorder. Altitude of gage is 930 ft (from river-profile map). 

Stage-discharge relation. Defined by current-meter measurements below 6,200

cfs and extended by logarithmic plotting. 

Remarks. Discharge for 1951 estimated by correlation with record for Sauk

River near Sauk, Wash.

Annual peak stages and discharges of Sauk River above Whitechuck River, near

Darrington, Wash.

Water year

1918 

1919 

1920.. . -. _ .......

1921 _ ..

1922... _ . _

1929..... . . ........ ...

1930. 

1931. 

1932, . _ .

1933. 

1934 

1935 

1936 

1937 

1938 

1939 _ .... .... ....

1940 

1941 

1942 _ .... 

1943. 

1944 .........

1945 . 

1946. 

1947. ....... . ......

1948 __ . ___ . _ . .... 

1949 

1950 ......

1951 _ -

1952 

1953 

1954 

1955 

1956 .....

1957 

Date

Dec. 29, 1917.....

Dec. 14, 1918.....

Nov. 15, 1919 

Oct. 4, 1920.......

Dec. 12, 1921.....

Oct. 9, 1928. .

Feb. 5, 1930 

Jan. 27, 1931 

Feb. 26, 1932.....

Nov. 13, 1932.....

Dec. 21, 1933.....

Jan. 25, 1935 

May 16, 1936 

Apr. 18, 1938. _ .

May 29, 1939 

Dec 15 1939

Oct. 18, 1940 

Dec. 2, 1941.... .. _ .... .... ... 

Nov. 23, 1942. .- _ _ -_ -- 

Dec 3, 1943

Feb. 7, 1945 . __ ..... ___ .... ... __ 

Oct. 25, 1945 . _ - ___ - _ _- __ 

Oct. 25, 1946 

Oct. 19, 1947 

TV/TOTT 10 iruQ

Nov. 27, 1949. _ .

Jan. 31, 1953 .

Oct. 31, 1953 

Nov. 18, 1954 

Dec. 10, 1956 __ -

Gage height 

(feet)

13.3

7.9 

9.0 

8.1 

14.65

7.50 

6.35 

7.72 

13.0 

10.3 

12.05 

10.41 

6.26 

6.19 

8.23 

7.60 

6.71 

5.94 

7.61 

7.06 

9.00 

8.40 

8.00 

8.50 

9.68 

6.52 

14.90

6.41 

8.17 

6.56 

6.76 

9.86 

8.19

Discharge 

(cfs)

24,400 

8,430 

11,400 

8,960 

29,100

7,030 

5,060 

7,410 

22,900 

13,000 

18,600 

13,200 

4,400 

4,310 

8,240 

7,010 

5,480 

4,180 

7,220 

6,230 

10,300 

8,940 

8,950 

10,200 

13,500 

5,660 

30,200 

20,800 

5,080 

9,360 

5,600 

5,990 

14,400 

9,650

19. Sauk River at Darrington, Wash.

Location. Lai 48°15'00", long 121°35W, in SW^ sec. 24, T. 32 N., R. 9 E., 

on right bank half a mile southeast of Darrington and 2% miles downstream 

from Clark Creek.

Drainage area. 293 sq mi.

Gage. Staff gage read once or twice daily. Altitude of gage is 525 ft (from riverprofile map). July 1914 to Apr. 14, 1922, staff gage 700 ft upstream at different datum. Gage heights are from graphs based on gage readings.

Stage-discharge relation. Defined by current-meter measurements below 7,700 cfs 

and extended by velocity-area studies.
FLOOD RECORDS 45

Annual peak stages and discharges of Sank River at Darrington, Wash.

Water year

1815.. ......................

1898... ..... .

1910...... 

1915.._ _ .... _ ...........

1916.. ..... .................

1917... 

1918. ___ . __ ..... _ . _ ..

1919.... ..--................

1920... ___ . __ ........ __ .

1921.. _____ .. _ ... _ ....

1922 

1923... . _ . _ ..

1924. ________________

1925... ..... ___ . _ ....

1926.. . _ . ___ . ___ ......

1929........... _____ . __ ...

1930...- ____________ ..

1931... _______ .... . _ ....

1932... _ . _____

Date

Nov. 1897- 

Nov. 29, 1909. ___ . _ . ___ . _ . __ ... _ - 

Apr. 2, 1915.. .. 

Dec. 8, 1915 _ __ . __ _ . __ ..

Nov. 9, 1916 _ - _ __ ... . __ .. .......

Dec. 29, 1917.. . 

Dec. 14, 1918. _ . ___ __ . ......

Nov. 15, 1919. __________ . _____ . ......

Oct. 4, 1920... _ .. ____ . _________ -

Dec. 12, 1921... ___ . _ . _____ . ____ ....

Dec. 24, 1922..... __ .. _ ... . . _ . ..........

Feb. 12, 1924-. 

Dec. 11, 1924.. _ . _ . __ . _ ......

Oct. 9, 1928-.. _ .... .

Feb. 5, 1930.. _ . _ . _____ ... ......

Jan. 27-28, 1931.. ....

Feb. 26, 1932. _____ ..... _ _ ....

Gage height 

(feet)

18.0

17.0

16.0 

8.8

7.4

6.2

15.0

9.7

10.5

10.1

15.0

8.0

12.1

9.0

7.5

8.5

7.1

8.4

16.0

Discharge 

(cfs)

4R flftfi

44,000

40,000 

16,500

12, 000

8,260

36,000

15, 100

17,200

16,200

36,000

12,300

27,200

15,500

10,800

13,900

9,630

13,600

46,500

20. Suiattle River near Mansford, Wash.

Location. Lat 48°21'50", long 121°29'30", in N^ sec. 10, T. 33 N., R. 10 E., 

left bank 1% miles downstream from Big Creek and 4 miles north of Mansford.

Drainage area. 335 sq mi.

Gage. Water-stage recorder. Altitude of gage is 530 ft (from river-profile map).

Stage-discharge relation. Defined by current-meter measurements below 15,000 

cfs and extended by logarithmic plotting.

Annual peak stages and discharges of Suiattle River near Mansford, Wash.

Water year

1939...... .................... .

1940.. __ - _ . ... 

1941.. ................ __ .

1942. 

1943... .....................

1944.. _____ ... ___ . ... 

1945 .. _ ..........

1946.... _ ..... _ ............

1947... ................ _ ..

1948. 

1949 

1950 

Date

May 29, 1939 _ .... _ __ . ___ ....

Dec. 15, 1939. ___ . __ . ___ 

Oct. 18-19, 1940 __ ...... _ ...

Oct. 3, 1941.. ____ .... __ ..... __ ...... ....

June 30, 1943 __ . ______ ..... ____ . ......

Dec. 3, 1943. 

Feb. 8, 1945.... ____ .. __ .. ___ . ...

Oct. 25, 1945 ___ - _ - _ - _ .... _ ......

Oct. 25, 1946 - _ - ___ .... ... ... .....

Oct. 19, 1947- _____ - ___ ... ... . ...

May 13, 1949 . _ ... __ ... ___ _ . ... 

Nov. 27, 1949 - _ . _ ..... ..... ... 

Gage height 

(feet)

9.79

7.97 

7.83

9,78

8.82

9.47 

9.70

10.90

12.86

12.33

9.89

15.60

Discharge 

(cfs)

9,680

5,580 

4,980

9,100

7,200

8,850 

9,520

12,600

19,200

18, 000

9,900

30,700
46 FLOODS IN THE SKAGIT EIVEH BASIN, WASHINGTON

21. Sauk River near Sank, Wash.

Location. Lat 48°25'15", long 121°34'00", in NW# sec. 19, T. 34 N., R. 10 E., 

on left bank 5 miles upstream from mouth, 5 miles southeast of Sauk, and 8 

miles downstream from Suiattle River.

Drainage area.- 714 sq mi.

Gage.' Water-stage recorder. Datum of gage is 266 ft above mean sea level 

(river-profile survey).

Stage-discharge relation. Defined by current-meter measurements below 40,000 

cfs and extended by logarithmic plotting.

Remarks.' Peak for 1912 from record obtained at several sites from 1 mile downstream to 5 miles upstream from present site during period 1910-12.

Annual peak stages and discharges of Sauk River near Sauk, Wash.

Water year

1912... _

1929-.. 

1930... . ... ..

1931.... ... ........ ......

1932.... .. .

1933... . 

1934. _____ . ...............

1935.._.__... ...-_.. ....._

1936. ____ . ................

1937 

1938-.. 

1939... __ .. __________

1940-.. .................

1941.... _ . 

1942 ___ ... __________

1943... ....................... . 

1944... 

1945..... ............... 

1946-..-.-... . ...........

1947... _____________ .

1948 

1949...... .... _ 

1950... 

1951....... .......... ..........

1952...........................

1953 

1954 ___ . __________ . 

1955 ___ . 

1956.. __ . __________ . 

1957..... ....... ...........

Date

Nov. 19, 1911 __ - __ - __________ - _ 

Oct. 9, 1928. __ . -

Feb. 5, 1930. __ . 

Jan. 28, 1931.. _____________ . - 

Feb. 26, 1932... _________ ..... 

Nov. 13, 1932.. 

Dec. 22, 1933 . 

Nov. 5, 1934. _________________ 

Apr. 18, 1938.. ______ - . - 

Jan. 1, 1939.. . 

Dec. 15, 1939 ______________ - _ ... _ -

May 17, 1941 __ . _____ ... .. 

Dec. 2, 1941. _______ . 

Nov. 23, 1942 ____ . ____________ . _ .. 

Dec. 3, 1943 __ . . _ 

Feb. 8, 1945 _____ - _ - _ 

Oct. 25, 1945...... ________________ -

Oct. 25, 1946..... _________ .... ...

Oct. 19, 1947. _____ ... - - 

May 13, 1949 

Nov. 27, 1949. ______ . __ . __ . . - 

Feb. 10, 1951 _______ . __ - _ . ...

Jan. 31, 1953. ___________ . __ - __ .. 

Dec. 20, 1953 __________ ........ -

June 11, 1955. _______ - _ ... . .

Oct. 25, 1955.. __ . _ .. . .

Dec. 10, 1956, _ - _____________ - __ -

Gage height 

(feet)

8.7

9.33

7.99

9.32

15.83

12.62 

14.40

13.54

8.33

8.15

10.78

9.96

9.00

6.80

8.85

9.02 

10.80 

10.28 

9.96

11.41

11.74 

9.03

16.93 

14.97 

7.65

10.56 

8.17 

9.56

12.23 

10.41

Discharge 

(cfs)

28,000

21,800

15,200

21,800

68,500

42,500 

56,600

49,400

16,600

15,900

29,900

25,200

20,000

7,980

19,000

19,500 

29,900 

26,800 

25,000

33,200

35,900 

19,700

82,400 

62,700 

13,600

28,400 

15,600 

23,900

40,600 

28,500
FLOOD RECORDS 47

22. Baker River below Anderson Creek, near Concrete, Wash.

Location. -Lat 48°39'50", long 121°40'25", in SEtf sec. 30, T. 37 N., R. 9 E., on 

right bank 100 ft downstream from Anderson Creek and 9^ miles northeast 

of Concrete.

Drainage area. 211 sq mi.

Gage. Water-stage recorder. Altitude of gage is 560 ft (from river-profile map). 

October 22, 1910, to Sept. 23, 1915, staff gage and Sept. 24, 1915, to Nov. 11, 

1931, water-stage recorder, 250 ft downstream from present site and at 

different datum.

Stage-discharge relation. Defined by current-meter measurements below 8,000 cfs 

and extended by velocity-area studies.

Annual peak stages and discharges of Baker River below Anderson Creek, near

Concrete, Wash.

Water year

1815... .......................

1898. .........................

1910 . ..................

1911. ......................... 

1912. 

1913. .. .................

1914 ... ... .....

1915. _______________

1916 ___ .... __ ............

1917-.. 

1918.. .. ......................

1919.. .....................

1920. .............. ........... 

1921. __ .......... ... ..... 

1922. . _-. 

1923. __________ . .......

1924. . ,. 

1926. ______ . ..............

1929. 

1930. .........................

1931. .........................

1966... .................. 

1957. .........................

Date

Nov. 1897. 

Nov. 29, 1909.. ___________________ .

Nov. 20, 1910. 

June 25, 1912. __ .. __ ... _____ ..... ....

Sept. 4, 1913... .......... ............. ......

Jan. 6, 1914 __________ . .................

Apr. 2, 1915. .. .. ......... .............

Feb. 15, 1916.- _____________ ........

July 16, 1917...... ..... - ..

T)AI> 9Q 1Q17

T>AI> 4. 1Q1R

Nov. 15, 1919 ______ - 

Oct. 4, 1920- 

Dec. 12, 1921 ___ . _____ . _____...- 

Dec. 24,1922.... .... __ . ____ 

Jan. 31, 1924... ......... ....................

Dec. 12, 1924. ___________________ ..

Oct. 8, 1928. . 

Feb. 18, 1930...... ........... ............. .....

Jan. 23, 1931 __ ... .... 

Nov. 3, 1955. ______ ..... _____ - ... 

Oct. 20. 1956. . . .

Qage height 

(feet)

16.0

13.5

15.3

10.0 

7.0

7.6

12.6

9.6

8.8

7.21

13.7

9.70

9.93 

9.74 

10.80

8.1

11.9

10.15

6.88

9.90

14.37 

11.78

Discharge 

(cfs)

50,000

36,700

df{ onn

20,000 

6,860

8,800

94. OTIA

17, 700

14,800

8,210

36,800

18, 700

19,600 

18,700 

23,600

11,800

28,500

17,000

20,900

7,390

19,600

20,100 

12,200
48 FLOODS IN THE SKAGIT EIVEiR BASIN, WASHINGTON

23. Lake Shannon at Concrete, Wash.

Location Lat 48°32'55", long 121°44'25", in SWK sec. 2, T. 35 N., R. 8 E., at 

Baker Dam on Baker River near left bank half a mile north of Concrete and 

1 mile upstream from mouth of Baker River.

Drainage area. 297 sq mi.

Gage. Staff gage or water-stage indicator. Datum of gage is at mean sea level, 

subject to adjustment to datum of 1929.

Remarks. Reservoir is formed by concrete dam completed to elevation 405.00 

ft in November 1925 and to 435.00 ft in June 1927. Storage began in November 1925. Capacity, 132,500 acre-feet between elevation 360 ft (lowest 

elevation for capacity operation) and 435 ft (spillway crest). Records furnished by Puget Sound Power and Light Co.

Annual peak stages and storage on last day of month of Lake Shannon at Concrete,

Wash. 1

Water year

1926... .. __ ..

1927--. __

1928.... _

1929 

1930.. 

1931. .... _ . _ ...

1932 

1933. _

1934. .. 

1935 

1936... __ . 

1937 

1938-.. . 

1939.. ______

1940...... ... __ 

1941.-.. 

1942. _ . _

1943... __ ..........

1944......... _ ___

1945...- . 

1946. . 

1947. _ ............ ___ .....

1948.. 

1949---..-... ___ . ___ . ...

1950-.-. __

1951.- _ . ____ .......

1952.... 

1953-- . _ ... _____ .

1954. . 

1955... ........... _ . __ .

1956... ______ .

1957. ___ .... __ . _____ ...

Date

July 1927 . __ _ .

July 1928 _ 

TUTa-ir 1Q9Q

Jan. 1931 _ _ . . ... __

July 1932-. ... __ . 

Nov. 1932.. . _ . __ ..... 

July 1934. _ . __ _ ......

Oct. 1934- 

Nov. 1937. 

July 1939 

TV^atr 1OJ.fi

TWav IQd.1

July 1943 __ ... 

TnTifl 1 Qjd.4.

Oct. 1945 ____ .... __ 

Nov. 1946 _ -. . __ .... _ ... ..

Dec. 1947. ... __ ___ . __ 

Nov. 1948.. _ 

Nov. 1949. . _ .. -. . __ ... _ ....

July 1952.. _ ..... ....... ... _ ...

Sept. 1953.. - 

Nov. 1954... __ .... ____ . __ __ 

Oct. 1955 _ . __ ____ .....

Aug. 1957 . _ ..

Elevation 

(feet, m.s.l.)

404.64

434.68

434.44

434.80

434.95

434.80

434. 90

434.80

434. 71

434.97

433. 53

434. 93

435.00

434.12

434. 61

435. «0

435.86

JOE CA

435.59

435. 26

435. 85

435.88

435, 82

435.83

435. 89

436. 16

436.86

436.55

436.75

436. 72

434. 81

Storage 

(acre-feet)

93, 350

155, 520

154,980

155, 790

156, 130

155, 790

156, 020

155, 790

156, 240

155, 590

156, 170

152, 940

156,080

156, 240

154,260

155, 360

157, 600

158, 180

157,600

157, 570

156,830

158, 160

158,230

158,090

158, 120

158,250

158, 860

160, 450

159, 750

160, 200

160, 130

155, 810

1 Figures shown for each water year are maximums of 12 end of month figures.
FLOOD RECORDS 49

24. Baker River at Concrete, Wash.

Location. Lat 48°32'35", long 121°44'35", on line between sees. 10 and 11, 

T. 35 N., R. 8 E., on left bank 800 ft downstream from Baker River powerplant, a quarter of a mile northeast of Concrete, and three-quarters of a mile 

upstream from mouth.

Drainage area. 297 sq mi.

Gage. Water-stage recorder. Datum of gage is 172.6 ft above mean sea level

(from river-profile survey). Prior to 1915, staff gage at site half a mile downstream at different datum.

Stage-discharge relation. Defined by current-meter measurements below 16,000 

cfs and extended on basis of computation of peak flow over dam and through 

power plant of 35,200 cfs, made by Puget Sound Power and Light Co. for 

flood of November 27, 1949.

Remarks. Flow regulated since November 1925 by Baker River powerplant and 

Lake Shannon.

Annual peak stages and discharges of Baker River at Concrete, Wash.

Water year

1911...... ................. _ .

1912................. .........

1913... .... ....................

1914..... _____ . _ . __ ...

1944...........................

1945 

1946... .................. ...

1947...-...-....... .. __ ...

1948... - _ - 

1949. _______ . .............

1950 

1951-.. .. _

1952 __ ... __ . ..............

1953. .............. __ ...

1954... ...... _ .... __ .. 

1955..... .... __ ........ ...

1956... __ .... _ ......

1957 

Date

Nov. 21, 1910 

Nov. 18, 1911.......... ..........................

Sept. 4, 1913 

Jan. 6, 1914.. .......................... _ ....

Dec. 3, 1943--. . _ ....... __ .....

Feb. 8, 1945-.- _ ...................

Oct. 25, 1945. __ . __________________

Oct. 24, 1946 _ .. ____ ..... _ ... ___ ....

Oct. 18, 1947... .. __

May 10, 1949.. ____________ . __ ......

Nov. 27, 1949 

Feb. 10, 1951.. ............................ ...

Oct. 19, 1951 .. _ ... ..... ..... ...

Jan. 12, 1953.. . _ ... ... ... ..... ... ...

Oct. 31, 1953. . ____ ......... _ .......... 

Nov. 18, 1954.. _ .... ... _ ..... _ -- .-...

Nov. 4, 1955. _ ......... _ __ ____ ......

Oct. 17, 1956 . __ . _ ..... _ -

Gage height 

(feet)

10.8

8.7

9.3

12.2

10.7

12.45

14.90

12.40

13.40

10.30

20.32

16.20

9.87

11.22

10.55 

11.99

15.07

12.67

Discharge 

(cfs)

24,600

14, 800

18, 100

31,000

14, 100

20,000

27,000

20, 000

23,000

12,600

35, 200

29,700

11, 000

16, 200

14, 200 

18, 500

26,900

20, 400
50 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

25. Skagit River near Concrete, Wash.

Location. Lat 48°31'30", long 121°46'10", in NEtf sec. 16, T. 35 N., R. 8 E., on 

right bank at The Dalles 1% miles southwest of Concrete and 2% miles downstream from Baker River.

Drainage area. 2,700 sq mi, approximately, of which 400 sq mi is in Canada.

Gage.' Water-stage recorder. Datum of gage is 130.0 ft above mean sea level, 

datum of 1929. Dec. 10, 1924, to Oct. 27, 1937, water-stage recorder at 

present site, at datum 12.69 ft higher. Gage heights given herein are to 

datum of present gage.

Stage-discharge relation. Defined by current-meter measurements below 135,000 

cfs and extended by logarithmic plotting.

Remarks. Flow partly regulated by powerplants on Baker and upper Skagit 

Rivers and by Lake Shannon Reservoir since 1926, Diablo Reservoir since 

1930, and Ross Reservoir since 1940.

Annual peak stages and discharges of Skagit River near Concrete, Wash.

Water year

1815. __ . ___ ... __ ..... .

1856...-.... -.-..- . 

1898... __ ... __ . _ 

1910.. ____ __ .......

1918... ____ . _ . __

1922..... _ ......... ..........

1925...... ..................

1926... ___ . ____ . .........

1927... ___ .. __________ .

1928... _____ . ..............

1929... _ . __ .... - .... 

1930...... ______ - ..........

1931... __ .. __ . __ . .......

1932... __ .... __ . __ . .... 

1933.......-..-.... ...... 

1934... ___________ . ....

1935..... _ ... . _ - ____ - ...

1936..... . .

1937....... __ _

1938....... .. ____ . .......

1939.. 

1940.. _ . __ . ____ . .......

1941...... __ ..... _______

1942... ____ . ................

1943.... ___________ . ...

1944. ____ . _________ . ... 

1945... 

1946...... _____ . . . ...

1947.... 

1948.... .. . 

1949......... .........

1950.. _____ _ - 

1951..... __ . ....... .........

1952.. ____ . _______ ...

1953.... ...... .........

1954... ____ . . 

1955.. ____ . ................

1956.. ________ ... .........

1957.... _ . _________ ....

Date

Nov. 19, 1897. . __________ .. _

Dec. 30, 1917 __ ... __ __ ... ___

Dec. 13, 1921... __ . __________ -. _ .

Dec. 12, 1924.. . 

Oct. 16, 1926... ___ . _______________ .

Jan. 12, 1928.. __ ... . _ . ___ . .............

Oct. 9, 1928.. . ____________ ......

June 26, 1931 _______________ . ......

Feb. 27, 1932.. ________ . _ . __ .... ......

Nov. 13, 1932.. _______________ . ____

Ttop 99 1 033

Jan. 25, 1935 ____________ . ___ .. ......

June 19, 1937 ___________ . __ ......

Oct. 28, 1937. __ . _________ . _ . ____ .

May 29, 1939 __________ .... _ ..... ......

Dec. 15, 1939 

Dec. 2, 1941.. __ .. _ . - . __ ..

Dec. 3, 1943 __ .... __ . ____ .... _ - _ ... 

Feb. 8, 1945... __ . ___ . ___ . . __ 

Oct. 25, 1945... _________ . __ . ...

Oct. 25, 1946. ___ . __________ ..... .... ... 

Oct. 19, 1947. _____________ . .. ...... 

May 13, 1949 ________ . ___ ......

Nov. 27, 1949. _________ . __ ..... __ . 

Feb. 10, 1951 ___ . ___ - - .... 

June 5, 1952. __________ . _____ . __ .

Feb. 1, 1953 ____ . ________ ...... _ . 

Oct. 31, 1953 ________________ - .......

Nov. 3, 1955. ____ . ____ . _____ . .......

Gage height 

(feet)

69.3

57.3

51.1 

49.1

45.7

47.6

32.44

26.3

32.03

32.9

29.94 

22.70

27.78

39.99 

35.6 

33.6

37.9

27.7

28.97

32.16

30.7

25.70

26.20

30.17 

26.69

28.49 

29.35 

34.0

31.14 

32.99 

26.97

40.8 

38.99 

24.80

28.61

27.39 

26.99

34.48

27.84

Discharge

(cfs)

500,000

350,000

275,000 

260, 000

220,000

240,000

92,500

51,600

88,900

95,500

74,300 

32,200

60,600

147,000 

116,000 

101,000

131, 000

60,000

68,300

89,600

79,600

48,200

51,000

76, 300 

54,000

65,200 

70,800 

102, 000

82,200 

95,200 

55,700

154,000 

139,000 

43,500

66,000

58,000 

55,600

106,000

61,000
FLOOD RECORDS 51

26. Alder Creek near Hamilton, Wash.

Location. Lat 48°31'40", long 121 WOO", in NE# sec. 18, T. 35 N., R. 7 E., 

on left bank at railroad trestle a quarter of a mile upstream from highway 

bridge, three-quarters of a mile upstream from mouth, and 2 miles east of 

Hamilton.

Drainage area. 10.7 sq mi.

Gage. Water-stage recorder. Altitude of gage is 125 ft (by barometer). Prior 

to Nov. 15, 1945, water-stage recorder at site 80 ft upstream at datum 2.46 

ft higher. Nov. 15, 1945, to Jan. 7, 1947, water-stage recorder at present 

site at datum 2.56 ft higher. Jan. 8, 1947, to Aug. 24, 1951, water-stage 

recorder at same site at datum 0.98 ft higher. Gage heights given herein 

are to datum of present gage.

Stage-discharge relation. Defined by current-meter measurements below 400 cfs 

and extended by logarithmic plotting.

Annual peak stages and discharges of Alder Creek near Hamilton, Wash.

Water year

1944.. ... _____ ... __ ..

1945. .. __ .. _ .. __ .. _ .

1946..-. _ ................

1947. ... . ........

1948. __ . . _ . ____ ......

1949. _ . _ . ______ .

1950. .... _______

1951. _ ... . _______ . ___

1952. ... _____ . __ . ......

1953. _ ______ . ......

1954. .........................

1955... _____ . _____ ..

1956. .

1957. . . .......

Date

Dee. 3, 1943. ...... .............. _ .. _ .. .....

Jan. 7, 1945 _ ... __ ....... _ ...... __ . ......

Oct. 25, 1945. .... ....... ........ ................

Dec. 11, 1946.. _ .. _ ........ _ ..... _ ...

Oct. 19, 1947... ____ .. __ ... ___ ..... .....

Dec. 1, 1948..... __ . ___ ...... .. ..

Dec. 27, 1949. __________ . ................

Feb. 10, 1951.. __ ..... ________ ..... __ ..

Feb. 4, 1952 .....................................

Jan. 31, 1953... ____ . _ . _ ........ _ .......

Dec. 11, 1953.---.. _ . ___ . __ . _ - .... 

Feb. 8, 1955 _ ..... _ .. _ .... ___ .... ... __

Nov. 3, 1955 ___ ........ _ ......... ...........

Dec. 9, 1956.. ______ - _ ___ - 

Gage height 

(feet)

5.38

6.74

5.93

5.17

3.55

3.75

4.24

4.90

3.56

4.23

3.80

3.84

4.11

5.38

Discharge 

(cfs)

1^7

265

450

241

256

477

654

212

364

239

295

363

360

27. Day Creek near Lyman, Wash.

Location. Lat 48°30'05", long 122°02'45", in NWtf sec. 28, T. 35 N., R. 6 E., 

on left end of county highway bridge, 1 mile upstream from mouth, and \% 

miles southeast of Lyman.

Drainage area. 36.3 sq mi.

Gage. Water-stage recorder. Altitude of gage is 90 ft (from topographic map).

Stage-discharge relation. Defined by current-meter measurements below 3,000 

cfs and extended by logarithmic plotting.

Annual peak stages and discharges of Day Creek near Lyman, Wash.

Water year

1944... __ . ...................

1946. ............ .............

1946. 

1947 .... _______ .....

1948. .. ......

1949. . 

1950. ____ . __ ... .........

1951 __________ . ........

1952. ....... ..................

1953 ________ . ____ . ...

1954. ________ .... ........ 

1955. _______ . __ ... 

1956. . ... 

1957. ...... .. ... .. ...

Date

Dec. 3, 1943... .......... . .. .

Jan. 7, 1945. ____________ . .......... ...

Nov. 14, 1945. _______ . _______ . __ -

Oct. 24, 1946-- . - 

Oct. 18, 1947 __ - ____ ____ .... .. 

Feb. 16, 1949 ________ . _____ . _ ... _ -

Dec. 28, 1949 __ . __ _ - __ ... 

Feb. 9, 1951 _________ . ___ . ___ . __

Oct. 2, 1951. _________ ..... ..............

Jan. 2, 1953 _ . ______ . ___ .... _

Oct. 30, 1953 ___________ __ - ___ - 

Feb. 7, 1954 _ . ___ . _____ . _____ . ... .. 

Nov. 3, 1955.. _____ . __ ..... _____ - __ .

Dec. 9, 1956- _ _ . -

Gage height 

(feet)

7.60

7.85

7.77

8.12

7.94

6.85

8.35

7.72

6.55 

6.81

7.07 

6.47 

8.27 

8.80

Discharge 

(cfs)

4,370

4,310

4,310

4,530

4,420

3,330

5,570

4,510

3,350 

3,890

4,180 

3,750 4,750' 

5,360
52 FLOODS IN THE SKAGIT RIVEiR BASIN, WASHINGTON

28. Skagit River near Sedro Woolley, Wash.

Location Lat 48°29'05", long 122°14'30", in NW^ sec. 36, T. 35 N., R. 4 E..

at Northern Pacific Railway bridge, three-quarters of a mile downstream

from entrance to Beatty Slough, and \% miles south of Sedro Woolley. 

Drainage area. 3,000 sq mi, approximately, of which 400 sq mi is in Canada. 

Gage. Staff or chain gages. Datum of gage is extreme low sea level in Puget

Sound (levels by Corps of Engineers), which is 8.93 ft below mean sea level,

unadjusted. 

Stage-discharge relation. Defined by current-meter measurements below 91,000

cfs and extended by logarithmic plotting. 

Remarks. Flow in Beatty's slough is included in tlrs record.

Annual peak stages and discharges of Skagit River near Sedro Woolley, Wash.

Water year

1815. . 

1856 . 

1897- - - _ -

1898.. 

1907 

1908 

1909-. 

1910 

1911. 

1912 

1913... _ ..

1914......... .

1915 

1916-- 

1917-- 

1918.. 

1919-- 

1922........ .. __ ...

1923.- 

Date

Nov. 16, 1896 _____ . _ . _____ . ___ - ...

Nov. 19, 1897 ___ . ____ - _________ . -

Nov. 16, 1906.. _________ . _ . _ . _____

June 11, 1908 __ ... ___ - _____ . __ . __

Nov. 18, 1908 _

Nov. 30, 1909- __ .... _ . ___ . _______ ..

Nov. 21, 1910... __ _

Nov. 19, 1911 _ , 

June 3, 1913. __ , ___ , .......................

Jan. 7, 1914 . __ . _____ . ___ . ___ . __

Apr. 3, 1915.. . _____________ .. .

June 18, 1916. _ .. .

June 16, 1917.. ________________ - __

Dec. 30, 1917 _ ...... _ . .

Dec. 4, 1918-- . __ . ____ - _______ - 

Dec. 13, 1921. _ ... _____ 

Dec. 25, 1922. _____________________

Gage height 

(feet)

63.5

60.0

54.8

54.9

54.7

47.8

52.0

56.5

52.1

48.4

46.4

49.6

45.4

46.5

44.4

54.1

47.0

54.3

45.2

Discharge 

(cfs)

400, 000

300, 000

185, 000

190,000

180, 000

48,200

97,000

220,000

114,000

66,600

70,800

104, 000

67,300

75,800

60,400

195,000

80,200

210,000

71,000

29. East Fork Nookachamps Creek near Clear Lake, Wash.

Location. -Lat 48°25'30", long 122°12'30", in NE>{ sec. 19, T. 34 N., R. 5 E., 

at county road bridge, 3 miles southeast of Clear Lake, and 3^ miles upstream 

from mouth.

Drainage area. 20.5 sq mi.

Gage.- Staff gage. Gage heights are from graph based on gage readings. Altitude of gage is 70 ft (from topographic map).

Stage-discharge relation. Defined by current-meter measurements below 1,900 

cfs and extended by logarithmic plotting.

Annual peak stages and discharges of East Fork Nookachamps Creek near Clear

Lake, Wash.

Water year

1945.... _ ......

1946. . _____ ...

1947 

1948 - -

1949...

1950 

Date

Jan. 7, 1945 . ______ . __ - _ - ___ - - 

Oct. 25, 1945... _________________

Oct. 24, 1946... . _ ___ - 

Oct. 19, 1947 . -- -.-- .

Feb. 17, 1949....

Dec. 28, 1949.. 

Gage height 

(feet)

8.59 

10.3 

110.0 

10.33 

10.05 

9.39

Discharge 

(cfs)

2,000 

2,710 

'2,120 

2,220 

2,130 

2,010

i Estimated.
FREQUENCY OF FLOODS 53

30. Skagit River near Mount Vernon, Wash.

Location. Lat 48°26'40", long 122°20'00", in SE^ sec. 7, T. 34 N., R. 4 E., on

drawrest of and 150 ft downstream from bridge on U.S. Highway 99 and 1

mile north of Mount Vernon.

Drainage area. 3,060 sq mi, approximately, of which 400 sq mi is in Canada. 

Gage. Water-stage recorder and, since Sept. 28, 1951, a crest-stage indicator.

Datum of gage is at mean sea level, datum of 1929. 

Stage-discharge relation. Defined by current meter measurements below 144,000

cfs. 

Remarks. Flow partly regulated by powerplants on Baker and upper Skagit

Rivers, and by Lake Shannon, Diablo, and Ross Reservoirs.

Annual peak stages and discharges of Skagit River near Mount Vernon, Wash

Water year

1907...- .. _ . _ . _____ .

1941... . ............... .....

1942.... ...-...-.-.........

1943 

1944...........................

1945.........................

1946.... 

1947. 

1948.. 

1949 

1950 

1951-. - 

1952 

1953..... _ .... -

1954.... __ 

1955 

1956..................... _ ..

1957 _ . . ....

Date

Oct. 20, 1940 _ . __

Dec. 3, 1941.- ._ ....

June 18, 1943 

Dee. 3, 1943..- . .........................

Feb. 8, 1945.. _ .

Oct. 26, 1945. _ 

Oct. 25, 1946 

Oct. 19, 1947.. _ 

May 13, 1949. _ .... . 

Nov. 28, 1949 __ . ____ __ . ___ -. ___

Feb. 11, 1951.- 

Feb. 1, 1953 ______________ - ___ ....

Nov. 1, 1953.. __ ....... ..... ......... _ .

Nov. 20, 1954.. . . _ __ ... _ ..

Nov. 4, 1955 

Oct. 21, 1956... . ....

Gage height 

(feet)

37

25.99

22.92

24.40

25.77

30.25

27.8

28.68

26.05

34.21

36.85

22.43

27.76

26. 37

27.10

33.52

27.47

Discharge 

(cfs)

180,000

i 44, 000

65,300

47, 000

55,700

59,800

94,300

64,900

en 4nn

56,200

114, 000

144,000

41,400

65, 700

57,900

62, 000

107, 000

64,000

' Maximum day.

FREQUENCY OF FLOODS 

SINGLE STATION FREQUENCY

Studies made by Benson (1960), and others, indicate that a long 

record is necessary before a reliable flood-frequency curve can be 

drawn. In order to come within 10 percent of the correct value 95 

percent of the time for a 50-year flood, a length of record of about 

110 years is required. In fact, to obtain this accuracy for even a 

10-year flood required 90 years of record. However, to come within 

25 percent of the correct value 95 percent of the time only about 39 

years are required. To obtain this accuracy for a 10-year flood 

required only 18 years. This study points out the undesirability of 

using a short record at a single station for constructing a frequency 

curve. For this reason historic data have been included whenever 

possible to lengthen the record. By using certain floods back to 

1815, a synthetic 143-year record was obtained.
54 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

FREQUENCY SERIES

Two types of flood series are the partial-duration series, based upon 

all floods above a selected base discharge without regard to the number of floods that occur in any one year, and the annual-flood series, 

based upon the highest flood that occurs each year. There are objections to both types. The partial-duration series may include floods 

that are not independent events, that is, the first flood sets the stage 

for the one closely following. The annual-flood series, however, may 

omit a second independent flood in a year that may be greater than 

many annual floods of other years. Both series give essentially the 

same results for recurrence intervals greater than 10 years.

The following table, derived from the statistical relationship between the two series, shows comparative values of recurrence intervals 

by the two methods:

Recurrence intervals, in years

Annual-flood series

1.16-. 

1.58.. ___ - ___ ... _ - __ -

2.00-.. 

2.54... _____________ . _

5.52. ______ ... .- ...

Partial-duration 

series

0.50

1.00

1.45

2.0

5.0

Annual-flood series

10.5. _ ... _ . _____ 

20.5 __ ..... _ - _ 

50.5 

100.5. 

Partial-duration 

series

10.0

20.0

50.0

100.0

There is an important distinction between the recurrence intervals 

of the two series. In the annual-flood series the recurrence interval 

is the average interval of time in which a flood of given size will be 

equalled or exceeded as an annual maximum. In the partial-duration 

series the recurrence interval is the average interval of time in which a 

flood of given size will be equaled or exceeded without regard to its 

relation to any period of time.

The annual-flood series has been used in this study. When it is 

important to know how often, on the average, a stream will exceed a 

certain discharge (as when designing a low fill, which will be overflowed during high floods), the partial duration series must be used. 

In such a case the use of the relationship expressed in the preceding 

table for converting the annual-flood series to the partial-duration 

series recurrence intervals will be entirely adequate.

PLOTTING POSITIONS

For plotting data based on the annual-flood series, the highest 

observed peak in each water year is listed in chronological order. 

Only complete years of stream-flow records should be used except in 

cases where a flood that occurs during a period of partial record is 

known to be the highest during the year. Also, historical flood data
FREQUENCY OF FLOODS 55

can often be used to advantage, and particularly to assist in defining 

the upper end of the frequency curve.

Numbers are assigned to each flood in the order of decreasing magnitude; the largest is designated as number one. Appropriate recurrence 

intervals are then assigned to each flood; they depend upon the order 

number, the period of record, and any additional historical information 

indicating the frequency recurrence.

Kecurrence intervals, T (time in years), are computed from the 

formula (7i+l)/m, where n equals the number of years of record and m 

equals the order of relative magnitude of the flood beginning with the 

highest as one. This formula is simple to compute, is applicable both 

to the annual-flood series and the partial-duration series, and gives 

results that conform with some of the latest theories.

Annual floods are plotted on a special graph based on the theory of 

extreme values for analysis of flood frequencies. On this plot the discharge having a recurrence interval of 2.33 years is the same as the 

arithmetical mean of an infinitely long series of annual floods and is 

known as the "mean annual flood." With relatively short records, 

such as are treated here, the "mean annual flood" is determined graphically from the gaging-station flood-frequency curves as the value of 

the discharge at a recurrence interval of 2.33 years.

HISTORICAL DATA

Historical data are of particular value where there is an account of 

all floods above a certain stage over a long period antedating the beginning of the stream-gaging record. The minimum or base stage 

covered by a historical account is generally high; more often it corresponds to flood stage, the stage where damage begins. Such a list 

of historical floods is in the nature of a partial-duration series above a 

high base; but, as there generally is only one flood of such magnitude in 

any one year, it may also be considered to be a partial list of annual 

floods. In either case the treatment is the same.

All floods, both historical and recorded, should be listed together and 

assigned recurrence intervals in the same manner as previously discussed, except that for individual historical floods the period of time 

for which they are known to be the highest must be considered.

In this report a 143-year base period (1815-1957) was used for the 

historical data because the flood of 1815 was known to have been higher 

than any since that date. It was assigned order number 1. In some 

cases the flood of 1856 was known to be the second highest flood and 

was given the order number 2. All other floods were assigned order 

numbers based on the period of time they were known to be 1st, 2nd, 

3rd, highest, and so on.
56 FLOODS IN THE SKAGIT RIVEK BASIN, WASHINGTON

In this report the historical floods were included in the data for the 

definition of frequency curves even though in some cases the natural 

regimen of the streams has been changed somewhat by the construction of dams to create storage reservoirs. As it has been stated previously, the Skagit River can now be almost completely controlled at 

Newhalem by Ross Reservoir.

The six stations where historic data are available for use are as 

follows:

Skagit River at Newhalem, Wash.

Cascade River at Marblemount, Wash.

Sauk River at Darrington, Wash.

Baker River below Anderson Creek, near Concrete, Wash.

Skagit River near Concrete, Wash.

Skagit River near Sedro Woolley, Wash.

Historic information was obtained for Skagit River at Reflector 

Bar, near Newhalem, but data for this station are for all practical 

purposes identical to that obtained at Newhalem so they were not 

used. Examples of the plotting of data for single station frequency 

curves, using historic information, are shown in the last part of this 

report. (See figs. 12 to 17.)

.FITTING FREQUENCY GRAPHS

A curve must be fitted to the data after a frequency diagram has 

been plotted. Many frequency curves tend to plot as straight lines 

on special plotting paper, which is a desirable feature if extrapolation 

can be justified. However, the use of the frequency graph for purposes of extrapolation may lead to fallacious results because the linear 

distance from 25 to 200 years is deceptively short on the plotting 

diagram and the error of a curve fitted by any method may be extremely great at its outer end. The data, not the functional theory, 

are used to define the graph so extrapolation can be justified only 

when the phenomena have proved to conform to the underlying law.

It is the practice of the Geological Survey to draw a visually-fitted 

line, either straight or curved, depending upon which best fits the 

plotted points. Sharp breaks in a curve are avoided by not giving 

full weight to the floods with the larger recurrence intervals because 

their true recurrence interval is seldom, if ever, accurately known. 

Thus it will be found that the curve as drawn may not pass through 

points that represent the one or two floods of largest magnitude.

REGIONAL FREQUENCY

A single-station frequency curve, particularly for the short records 

available, is a random sample and may not be truly representative of 

a region of like characteristics. For this reason a method of combining records for a number of stations has been developed to define a
FREQUENCY OF FLOODS 57

composite curve of median values to be applied to a basin or region 

as a whole.

SELECTION OF BASE PERIOD

In order that records of different lengths may be compared, it is 

necessary to select a common base period of record, either one that 

is common to all records or one to which such records may be extended. 

The base used herein is the 143-year period, 1815-1957; records for 

six stations were available. The 29-year period 1929-57 was also 

considered as a base for combining other station records in the basin, 

but it was not used because there was not enough record for the 

1929-57 period at the six long-term stations to develop a reliable 

method of combining the results from the two base periods. The 

short-term period was used in the determination of mean annual 

floods.

COMPARABLE MEANS

The value of the mean annual flood will vary with the length of 

the record from which it is derived and will be dissimilar for different 

periods of record even though the same number of years is being 

considered. For example, the mean annual flood obtained for the 

10-year period of record 1936-45 for Cascade Kiver at Marblemount 

would be lower than the mean annual flood for the period 1946-55 

because the peaks are of lesser magnitude during the earlier period. 

Also, the mean annual flood for the 20-year period 1936-55 would 

differ from both of the two 10-year period values and be somewhere 

between them. As the record increases in length, the mean annual 

flood can be determined more accurately.

The mean annual flood is the average of the maximum annual floods. 

It is determined graphically for each frequency distribution by the 

intersection of the visually best-fitting frequency curve and the mean 

line (the line corresponding to the 2.33-year recurrence interval).

For a flood record of length equal to that of the selected base 

period, the mean annual flood is obtained directly from the frequency 

graph. For stations where only a few years of record are missing, 

the mean annual flood is obtained for the base period in the following 

manner: peak discharges for the missing years of record are estimated 

by the correlation of floods at that station with those of nearby longterm stations. Order numbers may then be assigned to all peaks, 

but only those for actual years of record are plotted on the graph. 

The mean annual flood (adjusted) is then determined graphically in 

the usual manner. For short-term stations the method used is to 

compute the mean annual flood for the actual period of the shortterm station and then to adjust this value to the base period on the 

basis of the ratio of the mean annual flood for the same short period
58 FLOOD'S IN THE SKAGIT RIVEiR BASIN, WASHINGTON

at a nearby long-term station to the mean annual flood of the base 

period for the long-term station.

TEST FOR HOMOGENEITY

A test for homogeneity of records is necessary before a group of 

stations are combined. The test is statistical and is applied to the 

slopes of the individual frequency graphs to determine whether deviations from an average slope are such as may be due to chance alone.

The test was based upon the slope of the frequency curve determined by the ratio of the flood with a 10-year recurrence interval to 

the mean annual flood (2.33-year recurrence interval) at each station. 

The ratios thus obtained were averaged and the mean annual flood 

at each station was multiplied by the average value. The recurrence 

interval for this flood discharge was then determined and tested by 

statistical methods to determine that it would fall between permissible 

limiting values 95 percent of the time.

The six stations considered were found to be within these limits 

which indicated that they were homogeneous and could be combined.

COMBINING RECORDS

In order to combine the records to get a single median frequency 

curve it was necessary to express the frequency curve data in dimensionless terms. This was done by dividing the discharge at certain 

recurrence intervals at each station by the adjusted mean annual 

flood. This provided, at each station, a list of ratios for the designated recurrence intervals.

Median values for each of these recurrence intervals were computed 

for the 143-year base period. The medians were plotted on the frequency chart to define a composite flood-frequency curve, based upon 

the combined records and applicable to all streams within the basin; 

this curve is presented as figure 7. The composite curve is considered

85 3

345 10 20 

RECURRENCE INTERVAL, IN YEARS

FIGURE 7. Composite flood-frequency curve, Sfcaglt River basin.
FREQUENCY OF FLOODS 59

reliable to 50 years and fairly reliable to 100 years, but it should be 

extended further only with extreme caution.

Bodhaine and Robinson (1952) developed a composite frequency 

curve from the combination of 131 records from western Washington. 

The curve was based on a 40-year base period and, therefore, is different from the curve in this report. The change in the curve results 

from the use of the historic data. The Skagit River basin is the only 

area in the State where data have been collected for the historic floods 

of IS 15 and 1856; additional data were also obtained at several stations in the basin for unrecorded extreme floods of November 1897 

and November 1909. These data could not be used in a statewide 

analysis because they were only known to have occurred in the Skagit 

River basin. Since the composite curve of this report varies considerably from the curves computed for other areas, its use should be 

confined to the Skagit River basin.

FLOOD-EBEQUENrCY RELATIONSHIPS

In order that the composite curve may be used anywhere within 

the Skagit River basin, it is necessary to correlate the mean annual 

flood with some readily determinable physical characteristic of the 

drainage areas. Many characteristics that affect runoff (and consequently the mean annual flood) have been found by other investigators. Among these characteristics are size of drainage area, topography, type of soil, vegetation, stream slopes, lakes, elevation, rainfall, shape of basin, and others. Of these, the major characteristic 

and the one most easily determined is the size of the drainage area. 

Lack of adequate topographic maps prevents the determination and, 

consequently, the use of some of the above characteristics in a statistical study. The effects of others, such as rainfall and shape of basin, 

show such poor relations that they are of no material value.

The values of the mean annual floods mentioned previously under 

"Comparable means" were plotted against drainage area, on logarithmic graph paper, for each of the stations used in this study. The 

plotted points scatter considerably but may be divided into groups in 

which the relations vary in accordance with a series of three curves, 

each defined by various combinations of main stem and tributary 

stations; these curves are presented as figure 8, and areas to which 

each apply are shown on plate 1. The fact that three curves, rather 

than one, are defined reflects the influence of drainage basin characteristics, other than size of area, that may or may not be definable.

Bodbaine and Robinson (1952) show the same general grouping of 

streams as does this study. Size of drainage area was considered 

the primary factor in the present study because it has the greatest 

effect on the mean annual floods. The other characteristics that were
60 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

100

80

§ 60

30

5 20

< 10

1 8

L/ ^

y

20 60 80 100 400 

DRAINAGE AREA, IN SQUARE MILES

1000

FIGURE 8. Variation of mean annual flood with drainage area.

used elevations of drainage basin, geographical factor, and area of 

lakes and ponds also have an effect on the mean annual floods. The 

range in mean elevation of the drainage areas of the streams under 

consideration in the Skagit River basin is so small that a correlation 

with this factor cannot be made. The geographical factor is portrayed by the three curves shown in figure 8. The effect of lakes and 

ponds is small so this factor has not been considered.

The curves shown in figure 8 should not be extrapolated beyond the 

limits of the available data because to do so may lead to serious error. 

For additional study of drainage basin characteristics, see the publications listed in the bibliography.

FLOOD-FREQUENCY CURVES

To define a frequency curve at any place in the Skagit River basin:

1. Measure size of drainage basin, in square miles, above place where 

information is wanted.

2. Locate stream in one of the three mean annual flood areas (pi. 1).

3. Determine mean annual flood, in cubic feet per second, from proper 

curve of figure 8.
FREQUENCY OF FLOODS 61

4. Determine discharge in ratio to mean annual flood for several 

recurrence intervals, from figure 7.

5. Multiply the mean annual flood determined in step 3, by the ratios 

determined in step 4, to get the discharge corresponding to 

various recurrence intervals.

6. Plot discharges determined in step 5 and draw frequency curve.

Flood-frequency curves for six stations where historical data are 

available are presented in figures 9-14. The curves shown on each 

plot are computed from the composite frequency curve, shown on 

figure 7. The mean annual flood curve, shown on figure 8, serves as 

a means of comparing the actual data for each station with the 

average or computed curve.

1.0] 11 1.3 1.5 2 345 10 20 30 40 50 

RECURRENCE INTERVAL. IN YEARS

FIGURE 9. Frequency of annual floods, Skagit River at Newhalem, Wash.

100 200

. 

.01 1

 *

1 1

. 

'*

3 1

 " »*

s ;

-&**

> » i

 ~-^"^

> i

-*^

0 2

9

^

0 3

/

0 4

^

0 5

^/

0 1(X) 2C

RECURRENCE INTERVAL. IN YEARS 

FIGUKE 10. Frequency of annual floods, Cascade River at Marblemount, Wash.
62 FLOODS IN THE SKAGIT RIVER BASIN, WASHINGTON

1.01 1.1 1.3 1.5 345 10 20 30 40 50 

RECURRENCE INTERVAL, IN YEARS

FIGURE 11. Frequency of annual floods, Sauk River at Darrington, Wash.

1.01 1.1 1.3 1.5 2 345 10 20 30 40 50 

RECURRENCE INTERVAL, IN YEARS

100 200

FIGUEE 12. Frequency of annual floods, Baker River below Anderson Creek., near Concrete, Wash.

u. 400

345 10 20 30 40 50 

RECURRENCE INTERVAL. IN YEARS

FIGTJBE 13. Frequency of annual floods, Skagit River near Concrete, Wash.
SELECTED BIBLIOGRAPHY 63

345 10 20 

RECURRENCE INTERVAL, IN YEARS

FIGUBE 14. Frequency of annual floods, Skagit River near Sedro Woolley, Wash. 

SELECTED BIBLIOGBAPHY

Benson, M. A., 1960, Characteristics of frequency curves based on a theoretical 

1,000-year record, in Flood-frequency analyses: U.S. Geol. Survey WaterSupply Paper 1543-A, p. 51-74.

Bodhaine, G. L., and Robinson, W. H., 1952, Floods in western Washington, 

frequency and magnitude in relation to drainage basin characteristics: U.S. 

Geol. Survey Giro. 191, 124 p.

Carter, R. W., 1951, Floods in Georgia, frequency and magnitude: U.S. Geol. 

Survey Circ. 100, 127 p.

Cragwall, J. S., Jr., 1952, Floods in Louisiana, magnitude and frequency: Louisiana Dept. Highways, 281 p.

Dalrymple, Tate, 1950, Regional flood frequency: Washington, B.C., Highway 

Research Board, Research Rept. no. 11-B, p. 4-20.

Daly, R. A., 1912, Canada Geol. Survey Dept.: Mines Mem. 38, map 15.

Gumbel, E. J., 1945, Floods estimated by probability method: Eng. News-Rec., 

v. 134, no. 24, p. 833-837.

Langbein, W. B., 1949, Annual floods and the partial-duration series: Am. 

Geophys. Union Trans., v. 30, p. 879-881.

Schwob, H. H., 1953, Iowa floods, magnitude and frequency: Iowa Highway 

Comm., Iowa Highway Research Board Bull. 1, 171 p.

Stevens, J. C., LaRue, E. C., and Henshaw, F. F., 1911, Surface-water supply of 

the United States, pt. 12, North Pacific Coast: U.S. Geol. Survey WaterSupply Paper 272, p. 489.

U.S. Congress, House of Representatives, 1933, Report containing a general plan 

for the improvement of Skagit River, Washington, for the purposes of navigation and efficient development of its water power, the control of floods, and 

the needs of irrigation: U.S. 73d Gong., 2d sess., H. Doc. No. 187, 110 p.

INDEX

Page

Abstract....-_____...___.___.___ 1 

Alder Creek, gaging-station records_____ 51 

Altitude, effect on climate__________ 6-8

Bacon Creek, gaging-station records _.... 41

Baker, Mount_________________ 8

Baker Dam..,_________________ 16

Baker River, discharge data_________ 24 

gaging-station records.....________ 47,49

Beaver Creek, gaging station records_____ 33

Bibliography, selected_____________ 63

Birdsview, Wash., floodmarks.._..____ 27

Brooks, Dr. Charles F. quoted________ 10

Cascade River, course.____________ 23

discharge data . . . 23

gaging-station records ___ 42-43

Chinook_ 9-10, 27-28

Climate.. ..._ 6-8

Concrete, Wash., flood data_________ 24 

floodmarks-. 26, 27, 28, 29

precipitation records.__.______ 7,13,14

Damage, flood_._____________ 3,18-20 

Darrington, Wash., flood data.. _______ 24

temperature and precipitation ______ 7 

Day Creek, gaging-station records for _... 51 

Delta of the Skagit River... ........ 5-6

Diablo Dam ___ ...._. 5,14,16

Diablo Dam weather station, precipitation

records-__ _ _ ___ 13,14 

Diablo Reservoir__......... .... 5,14,15-16,37

Dikes___......__............. 17,18, 29, 30-31

Drainage, area....__ _____ _... 1, 5-6

changes in__ _ . _ _ 8

East Fork Nookachamps Creek, gaging-station 

records for....__..__.__... 52

Flood data, historical_____________ 22-25 

Flood-frequency curves . . 60-61 

Flood peaks, duration of._...._______ 11-14

effect of precipitation on_________ 11-14

See also Gaging-station records.

Flood photographs____________ 4, pis. 3, 4

Flood plain. . ____ 18

Flood profiles____________-____ 18

Flood records, combining records._ .. 58

kinds. . 31

mean annual... __ .. __ 57-58

tests for homogeneity.__.__ __.. 58

Floods, December 1917.. __........ 2, 22, 29

December 1921 3, 22, 29

description____.___..__ __.. 9-18 

February 1932..... 3, 22, 29-30

February 1951 3,13-14,17, 22, 30-31

Page

Floods, December 1917 Continued

frequency.. ._._ _________ 53-63 

For detailed listings see under Frequency of floods. 

Indian legend of 1815_........... ... 25-26

long-duration_______________ 13-14 

November 1897.. __ 2,21,27 

November 1896.___.__.______.. 2,21 

November 1906.___.__.._.____ 2,22 

November 1909 2,22,28-29

November 1949 _.... 3,11-13,22,30

short-duration_______________ 11-13 

summer . . .... 11,27

tree-staining, 1856.....__..... ......... 26-27

types_____._____________ 9

Frequency of floods, annual flood series. __ 54 

partial-duration series.--, . __ 54 

plotting data_ ______.__..__ 54-55 

plotting the frequency curve ______ 56 

recurrence intervals.. _ . . __ 54,55 

regional. ___.___ _.__ __ 56-57 

relationships________. ______ 59-60 

selecting base period .. 57 

undesirable use of single station record._ 63

Gaging-station records_____. __ _ 31-53 

Geography____________________ 4-6 

Glacier Peak.- 8

Glaciers __ _ - 8 

Gorge dam and powerplant ________ 5

Historical data, value . 55-56

History, geologic-... ... _ .. 8-9

of floods. ... 2-3,20-22

of settlement - 2,20 

Hydroelectric-power project 5

Introduction __ . 1-4

Marblemount, Wash., flood data...__ . 23 

precipitation records 13,14 

runoff __ - 7

Mean annual flood, comparison of means 57 

defined... 55

Newhalem, flood of 1909__........ 29,30

Powerplants_..__ 5 

Precipitation 6-8,10,11-14 

Precipitation records..__ __ 7,13,14,21 

Previous investigations-_ 3-4,10 

Purpose of this report- 3

Reflector Bar, flood data . 23 

floodmarks 25-26,27,28

Reservoirs, effect of ___ -- 14-17

65
66 INDEX

Page 

Eockport, flood of 1897. ............._... 28

Indian legend flood, 1815..________ 26 

Eocks . . . 8-9 

Boss Dam .. .. ...... 5,14-15

Eoss Reservoir... __ __..._ 5,15-16,35 

Euby Creek, gaging-station record______ 34 

Eunoff, comparison of, at various stations.... 7

in winter . _. 10

Sauk River, discharge data.._... .___ 24

gaging-station records_________ 44-45,46

Sedro Woolley, estimated flood stage for 1815. 26

flood data-- -- - 25

precipitation records ___.__ 7,13,14

tree-staining floodmarks._________ 27

Shannon, Lake, gaging-station records____ 48

Skagit powerplant, precipitation records. 7,13,14

Skagit River, course._____________ 4-6

discharge data_____________ 23,24,25

See oZso Skagit River, gaging-station

records.

Page

Skagit River Continued

drainage area.__..__ .. . 1,4-6

, gaging-station records 32-34,

35,38,40-41,42,43,50,52,53

Sloughs.___._ . 6 

South Fork Sauk River, gaging-station records.. . 43 

Sterling Dam... .___..._...._.. 17 

Stetattle Creek, gaging-station records . 39 

Summer floods.- ___._______.___. 11,27 

Sulattle River, gaging-station records. 45

Temperature ------------ -- ---- 6-7

Thunder Creek, gaging-station records , 36

Winds-.. . . 6,9-10,27-28

Winter floods, cause .__ .- .. 9-10

dates of occurrence. _ 10

runoff.._,__ ... 10

shape of profile-.- __ - 11,12,13

o