UNITED STATES

DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMATION

SEDIMENTATION RESURVEY

OF

GUERNSEY RESERVOIR, 1957

NORTH PLATTE PROJECT, WYOMING AND NEBRASKA

Sedimentation Section Report

HYDROLOGY BRANCH

DIVISION OF PROJECT INVESTIGATIONS

COMMISSIONER'S OFFICE

DENVER, COLORADO

r

AUGUST 1958
UNITED STATES DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMA'flON

SEDIMENTATION RESURVEY

OF

GUERNSEY RESERVOIR, 1957

Sedimentation Section

Hydrology Branch

Division of Project Investigations

Denver, Colorado

August, 1958
/

/

A
1957 SEDIMENTATION RESURVEY OF GUERNSEY RESERVOIR

CONTENTS

........................

................

........................

.........................

......................

..................

.......................

................

..............

..................

...................

................

......

..........

.........

................

..................

..............

.................

...........

....................

......................

Page

Introduction 1

Purpose and Scope of Report 5

Ownership 5

Location 5

Purpose Served 6

Power Development 6

Irrigation 6

Description of the Dam

Description of the Reservoir 8

Description of the Drainage Area 8

History of 1957 Resurvey 10

Preliminary Work 10

Depth Recorder Survey 10

Sediment Density and Size Distribution Survey 13

Density and Size Distribution of Sediment 14

Sediment Disposition in Guernsey Reservoir 27

Longitudinal Distribution 27

Lateral Distribution 29

Sediment Disposition Curves 29

Area-Capacity Curves 30

Sediment Distribution by Segments 31

Statistical Summary 35

Trap Efficiency 36
CONTENTS (Continued)

...........

.......

....... ........

.....................

......................

Page

Channel Condition Below Guernsey Dam 37

Future Sediment Deposition in Guernsey Reservoir 38

Summary . . . . . . . 40

Acknowledgment 42

Bibliography 43
LIST OF FIGURES

...............

..........

.........

.............

.............

.............

.................

..........

.......

............

.................

...........

............

.............

..............

.......

.............

.............

Figure Description Page

1 North Platte River Basin 3

2 Depth Recorder Equipment (Photo) 15

3 Guernsey Reservoir and Dam (Photo) 16

4 Guernsey Reservoir (Photo) 17

5 Guernsey Reservoir (Photo) 18

6 Sub-AquEous Sampler (Photo) 19

7 Radioisotope Sediment Densitometer showing major

components (Photo) 20

8 Radioisotope Sediment Densitometer with probe in

retracted position in shield (Photo) 21

9 Sample Form for RSD Field Notes . . 22

10 Sediment Size Analyses Curves 45

11 Correlation of Density with Location and Penetration

ofSedimentSamples 47

12 Longitudinal Profiles of Thalwegs

13 Typical Cross-Sections . .

51

14 Sediment Disposition Curve

15 Area and Capacity Curves 55

16 Degradation Ranges Below Guernsey Dam

17 Reservoir Topography-1947

18 ReservoirTopography-1957 63
LIST OF TABLES

Table Description Page

1 Size Analyses of Sediment Samples from

Guernsey Reservoir ............ ... 25

2 Density of Sediment Samples from

GuernseyReservoir ............ ... 26

3 Area-CapacityTable ............. ... 32

4 Sediment Distribution by Segments

1947-1957 ................. .. . 33

5 1927 to 1957 Sediment Distribution

by Segrrterits ................ . . . . 34
1957 SEDIMENTATION RESTJRVEY OF GUERNSEY RESERVOIR

Introduction

Guernsey Dam, which impounds the water of Guernsey Reservoir,

was completed in 1927. Guernsey Dam is located on the North Platte

River near Guernsey. Wyoming. The reservoir originally had a capacity

of 73, 810 acre-feet, and due to the sedimentation process, the capacity

had diminished to 49,150 acre-feet by 1947.

Guernsey Reservoir is utilized as a storage reservoir for the

irrigation water supplied to the extensive downstream irrigation interests

and for power production.

The results of a sedimentation resurvey of Guernsey Reservoir,

performed in July of 1957, are presented in this report.

The objectives of the 1957 resurvey were to establish new areacapacity curves, and to determine the effect of the sedimentation process

on the reservoir for the 10-year period from 1947 to 1957. It was necessary to perform the resurvey in 1957 so that the Sediment accumulation

could be determined prior to the October 1957 closing of the newly constructed Glendo Dam. Glendo Darn is 16 miles upstream from the high-

• water line of Guernsey Reservoir, and it will greatly reduce the sediment

inflow to Guernsey. This will extend the useful life of Guernsey Reservoir for many additional years.

This 1957 resurvey was performed jointly by the Bureau Project

Office in Casper, Wyoming, and the Sedimentation Section of the Cornnii -

abner's Office In Denver, Colorado.

I
-

-

A WOfl Soppy Obob

4 '-

,i

I Gohn,bo. bfcb F Bob Cr.ob Dtcb I Lofl,b Pdr Tonob A Skbn. Dtcb F COne Ps.. 4t cb - A Mcbg Ditob -

EXPLANATION

E1STING OR

UNB CONS1RtTiOB° ____________________

Reurvoir

tJviriion Dam

Canal

Tronstniuton Une ----------------------St----

Powerlant

Subtatlon

lrriat*d Lend

DivisIon

- jt 1J E

Gloobo Omo, Bos-sol ood Po*.flploot sod FoOb Ctmyon

Poonoploot md.r OOmfrOOPOv 0 057

UNITED STATES

_________________ _________________ DEPARTMmT OF THE INTERIOR

BUREAU OF RE(LAMATION

REGION 7

_________ _________

NORTH PLATTE RIVER BASIN

COLORADO

-WYOMING

- NEBRASKA

________________________________ JUNE 1957

000CC 00 01110

I-,

3 Figure 1.


Purpose and Scope of Report

The purpose of this investigation was: (1) to obtain the necessary data for preparing new area-capacity curves for Guernsey Reservoir, (2) to determine the sediment yield for the drainage area above

Guernsey Reservoir for the 10-year period from 1947 to 1957, (3) to

obtain information on the sediment disposition, gradation, and trap efficiency for this reservoir, and (4) to determine the total deposition of

sediment in Guernsey Reservoir prior to the closing of Glendo Dam.

The analysis of these data should provide information needed for

the efficient operation of Guernsey Reservoir, aid in estimating the useful

life of the reservoir, assist in the design of other structures relative to

increasing the usefulness of the projects, and provide a basis for the de -

termination of the sediment trap efficiency of Glendo Reservoir, which is

immediately upstream from Guernsey Reservoir.

Ownership

Guernsey Dam and Reservoir are owned by the United States Government and operated by the Bureau of Reclamation, Department of the

Interior.

Location

Guernsey Dam is 2 miles northwest of Guernsey, Wyoming, and

impounds the water of the North Platte River.

Guernsey Reservoir is located in Sections 5-10, 15-18, 20-22,

27 and 28, T. 27 N.,, R. 66 W.; Sections 35 and 36, T. 28 N., R. 67 W.;

and Sections 1, 2, 10, 11, and 12, T. 27 N., R. 67 W., Platte County,

Wyoming.

5
The drainage area of Guernsey Reservoir below Alcova Dam in.-

cludes parts of Natrona, Carbon, Converse, Albany, Niobrara, and

Goshen Counties Wyoming, in addition to Platte County in which the reservoir is entirely located.

Purpose Served

Guernsey Dam was built by the Bureau of Reclamation as a feature of the North Platte Project, and was completed in 1927. It is used

for storage of irrigation water, to reregu]ate Alcova releases and inflow

below Alcova, and for power production. An effort is made to have the

reservoir full at the start of the irrigation season. Releases from

Guernsey Reservoir during the irrigation season are those required to

meet the irrigation demands of the North Platte Project and other irrigators exercising a demand on the flow of the river.

Power Development

The existing Guernsey Powerplant utilizes an operating head

ranging from 55 feet to 95 feet. Over the 29-year period 1928-1956, generation has averaged 20, 100,000 kw-hrs annually. The presently installed plant capacity is 4,800 kw.

Irrigation

The area downstream on the North Platte River exercises demanda on water stored at Guernsey. Releases from Guernsey Reservoir

average about 1,130,000 acre-feet per year. The principal agricultural

products grown on the land irrigated by the North Platte Project are sugar

beets, potatoes, beans, corn, and alfalfa. The length of the growing season is about 5 months.
Description of the Dam

Guernsey Dam is located in a rocky canyon of the river. The

dam consists of an impervious embankment of sluiced clay, sand, and

gravel protected with a thick layer of rock riprap. The crest is about

135 feet above the foundation, 95 feet above the river bed, and 10 feet

above the normal high-water line fixed by the crest of its spillway gates.

The crest is 560 feet long and 25 feet wide. A roadway on the crest

crosses the dam to the north spillway and extends to recreation areas

along the north shore of the reservoir. At normal high-water stage, the

north spillway can discharge 52, 200 cubic feet per second and the south

spillway 26, 200 cubic feet per second.

The powerplant intake sill is at an elevation of 4, 360 feet. This

intake has a slide roller gate, 20 by 26 feet, which is electrically operated. The intake is connected with the south spillway tunnel and the

penstock tunnel, which is 12 feet in diameter by 662 feet long.

The existing powerplant consists of two 3, 400-horsepower

vertical Francis-type turbines and two 2,300-volt, 3-phase, 60-cycle

synchronous alternators. The rated capacity of each unit is 3, 000 kva.

Water is supplied to the turbines from the power intake structure located

near the dam's right abutment. A 20-foot-diameter shaft enters a

blocked-off section of the original river-diversion tunnel, which is utilized as a desilting chamber. The power water then flows through a

12-foot-diameter pressurized tunnel, a 144-inch-diameter steel penstock

with surge tank, and two 102-inch-diameter pipe branches to the turbine

valves in the powerhouse. The 49- by 72-foot concrete and steel building

is equipped with an overhead crane and other auxiliary equipment.

7
Description of the Reservotr

The present area of the reservoir at the crest elevation of 4,420

feet is 2,382 acres. This is 4 acres less than in 1947 and 23 acres less

than the original 1927 area of 2,405 acres. Its present capacity is 44,800

acre-feet which is 4,350 acre-feet less than in 1947, and 29,010 acre-feet

less than original 1927 capacity of 73, 810 acre-feet.

The length of the reservoir from the dam to the head of the reservoir is 14.6 miles.

The width of the reservoir at the dam and for a distance of about

5 miles above the dam is narrow, ranging from less than 500 feet to approximately one-fourth mile in width. Both sides of the valley along this

portion of the reservoir are steep and generally canyon-like. Above this

reach the reservoir broadens out over a 4-mile stretch, ranging from

about 1/2 mile to almost 1 mile in width.

At Range lOB, which is 9 miles upstream from the dam, the reservoir narrows again and winds through a canyon for 3 miles, ranging

from 1/4 mile to 300 feet in width. Upstream from this point the slopes

of the valley sides are less steep, but the reservoir remains narrow to

its headwaters. The head of the reservoir is opposite Wendover, Wyoming, and about 1/4 mile above the mouth of Cottonwood Creek.

Description of the Drainage Area

For the general description of the drainage area to Guernsey

Reservoir, the reader is referred to pages 3, 4, 5,, and 6 of the report - -

entitled, "Sedimentation Survey of Guernsey Reservoir," published by

the Bureau of Reclamation in November, 1948.

8
The North Platte River drains an area of 16, 200 square miles

above Guernsey Dam, of which 10, 800 square miles of this area is above

Alcova Dam. The sediment-contributing area to Guernsey then, for the

period of this report from 1947 to 1957 is 5,400 square miles.

The climate at Guernsey Dam is typical of the semiarid high

plains in which the dam is located. The winters are long and cold. Extreme temperatures have ranged from _27o F. to 1040 F. The mean

minimum and maximum are 11.90 and 40.30 for January and 56.70 and

89.70 for July. The average annual precipitation is 14.79 inches,

ranging from an average of 0.36 inch in February to 2.88 and 2.89 inches

in May and June. Snowfall amounts to about 40 inches during the winter

months. The maximum precipitation for 24 hours within the drainage basin was 4 inches at Elk Mountain on April 25, 1924, and also at Fort

Laramie on June 28, 1947.

The average annual outflow of water from Guernsey Reservoir

for the 30-year period from 1928 to 1957 was 1, 134, 800 acre-feet per

year. The average outflow for the 10-year period from the 1948 water

year through the 1957 water year was 1,023, 600 acre-feet. The 4 years

from 1954 through 1957 were unusually dry, with an average outflow of

805, 200 acre-feet of water per year.

9
HISTORY OF 1957 RESURVEY

Preliminary Work

The resurvey of Guernsey Reservoir was begun on May 7, 1957,

when a survey party from the project office at Casper, Wyoming, began

locating and flagging range ends. Some range ends were missing and had

to be reestablished; others which had been lost due to sloughing of the reservoir banks were reestablished back from the original locations.

Upon completing the flagging of the range ends, the survey crew

proceeded to rerun the aggradation and degradation ranges at Wendover

and in the channel downstream from the dam.

Depth Recorder Survey

The main portion of the Guernsey resurvey started on July 9,

1957, with the traversing of the ranges by boat using the supersonic Edo

Depth Recorder. This work continued for about 2-1/2 weeks and progressed from the dam to the upstream end of the reservoir. In the delta

area where the water was too shallow for the boat to navigate, the ranges

were surveyed on foot with a leveling instrument and rod.

A brief description of the techniques involved in surveying with

the survey recorder is given so that future parties who may be inexperienced in reservoir surveys can more quickly get organized and perform

their work.

The party consisted of five men who were assigned to the follow- -

ing positions:

1. Depth recorder operator (Boat)

2. Flagman (Boat)

3. Boat operator (Boat)

10
4. Transitman (Shore)

5. Plane table man (Shore)

The transitman was located at the end of the range to be run, and the plane

table man and his recorder were located at another known point at an approximate right angle to the range line from which the entire range was

visible. These men used a jeep to get to these points where convenient,

and where not, they were transported by boat. While the instrument setups

were being made, the depth recorder operator and flagman proceeded to

the range end opposite the transitman and began a hand level survey from

the range end to the water edge. One or two shots were taken in the water

in the area too close to shore for the boat to safely maneuver to define the

slope. The water's edge and range end were located by the plane table

man utilizing radio communication. The next step was to drive the boat

along the range towards the transitman at a speed of 2 or 3 knots with the

depth recorder in operation. The boat was kept on line by continuous direction from the transitman using a flag. On long ranges the radio was

used by the transitman. Before the beginning of the boat run, a standby

signal was given by the flagman. Once the boat was in position, the flagman called "Mark," and signaled with his red flag to the plane table man.

At that instant the depth recorder operator marked his chart and noted the

time to seconds which was given him by the flagman. A 15-second interval

was used between marks and each fifth mark was signaled by a white flag.

Upon completion of the run the last mark was made and the time recorded.

The time interval was then checked against the number of mark periods

and the number of marks then checked by radio with the plane table man

to insure against any mistakes. The next step was to survey the line

11
between the range end and water edge near the transitman and to get 1 or

2 shots in the water close to shore. The check bar setting, frequency of

power supply, draft of transducer, direction of run, and other pertinent

data were recorded in a field book. This same general procedure was

performed throughout the entire day except for check bar settings which

were made three times each day. The check bar setting consisted of

lowering a steel plate into the water to the average depth of the ranges surveyed and adjusting the frequency of the power supplied so that the depth

recorder exactly registered the depth of the plate. A check was then made

at the greatest depth of water and at 5 feet to determine the maximum

variance of the recorder chart with the actual depth of the plate. On this

resurvey, the largest variance was about 0.3 feet.

The water surface elevation as read at the dam 2 or 3 times each

day was used for vertical control except in the upstream area of the reservoir where a level circuit was run in from a U. S. Geological Survey benchmark. In the upstream area of the reservoir where the water was too shallow for operation of the depth recorder, the procedure was as follows: A

small boat was used and measurements were made by lead sounding line.

At each measurement the flag was waved for the plane table man and the

depth recorded in a field book. Two men were in the boat, plus one at the

transit and one at the plane table. This permitted the two remaining men

to run the level circuit along the shoreline to tie in the water surface ele- *

vations which were no longer truly indicated by the dam site recorder. In

some places where there was no water, the two men in the boat were required to proceed on foot with level instrument for vertical control.

12
Sediment Density and Size Distribution Survey

Upon completing the survey recorder work, the next phase was to

*

collect sediment samples and to measure the in-place density of the sediment. On July 23 and 24, 1957, work was commenced with the SubAqueous Sampler and the Radioisotope Sediment Densitometer (RSD).

This was the first reservoir work where the RSD was primarily relied

upon to determine the in-place density of the reservoir sediment deposition

The Sub-Aqueous Sampler was used to collect samples from which size

analysis tests could be made in order that sediment distribution by size

throughout the reservoir would be known.

The Sub-Aqueous Sampler is shown in Figure 6 with the A-frame

attached to the boat ready for use. The sampler was lowered from the

boat by cable and allowed to penetrate the sediment deposits to a predetermined depth. The maximum penetration was governed by the compaction of the sediments, the deepest penetration in Guernsey Reservoir being

6 feet. Eight samples at varying degrees of penetration were taken with

the Sub-Aqueous Sampler from near the dam to the delta area of the reservoir. Besides these 8 samples, 2 more were taken in the sand and gravel

area of the extreme upper end of the reservoir by pushing a plastic tube

into the bed by hand.

The Radioisotope Sediment Densitometer is shown in Figure 7

and Figure 8. The RSD with the probe in the retracted position was transported to the measurement site. It was then lowered over the side of the

boat until only a couple of inches of the working shield was above water.

The probe was thenlowered to the extended position and the cap removed.

The dosimeter was charged, read, andplacedinthe probe. Atthe momentthe

13
dosimeter was in position, time was started. The probe was then capped

and the RSD lowered to the desired depth. When the probe entered the

sediment the time was recorded as "time into sediment." After the required test time had elapsed the RSD was raised. When it left the sediment the time was recorded as "time out of sediment." When the original

position was reached the probe was uncapped and the dosimeter withdrawn

and the final reading taken. The time the dosimeter left the probe was recorded as "stop" time. The computations were then immediately made on

the form as shown in Figure 9. If the computed dry denaity was unusual

in any respect, another measurement was made to check the results.

The cobalt 60 source used in the RSD can present a definite radiation hazard if the probe is unshielded. It is important to work quickly

when the probe is out of the water, or when the dosimeter is being placed

in or removed from the RSD. The cobalt 60 source should be installed and

removed only by properly trained personnel, and all men in the crew

should wear personal dosimeters which should be read daily to check upon

the radiation received by the crew.

DENSITY AND SIZE DISTRIBUTION OF SEDIMENT

Twenty-three samples were taken in Guernsey Reservoir for the

purpose of determining the density of the sediment deposition and the distribution of the sediment sizes throughout the reservoir. Thirteen of the

samples were with the Radioisotope Densitometer, which were for the determination of the density of the sediments. Ten other samples were used

for size analysis data and also for density of the sediments, which were

determined in the Bureau laboratory. Eight of these samples were taken

14
-.--

-;> :-•;

4p

I

-, :

£

Depth recorder equipment in normal position for operation

to survey profile of reservoir cross-section.

15 T'icnir ')
.Ij I

0

CD

'I

U)

CD

CD

U)

CD0

I-..

C) 00p

0

CD

II

U)

CDI
I

Guernsey Reservoii' from left bank looking

upstream. Range 20 is located in center of photograph.

Guernsey Reservoir in vicinity of Range 18.

17 Figure 4.

I r

14
Guernsey Reservoir with Long Canyon to

right and gap leading to the lake portion of the reservoir in the background.

Lake portion of Guernsey Reservoir showing low relief and flat beaches.

Figure 5. 18
r

* Sub-Aqueous Sampler and A-Frame in position ready for

lowering into the reservoir sediments. Plastic tube is located

inside 2-inch pipe stem and held in place by cutter-head. Disklike lead weight supplies the penetration force and valve in pipe-tee

at top of pipe stem prevents sample from falling out of plastic tube

when apparatus is raised.

19 Figure 6
•

H • ;••

- ••- .-• -

4 -•- - -

Radioisotope Sediment Densitometer Photo shows the major

components of the RSD:

1. Storage shield 5. Lead column to separate

2. Working shield source and detector

3. Dosimeter Charger 6. Dosimeter

4. Probe shell 7. Dosimeter holder

c11r 7 2(1
?t

,

Radioisotope Sediment Densitometer with the probe in the

retracted position and in the storage shield.

'r-, S'il v:--.--'

-

,.

21 Figure 8
Sample Data Sheet

Sheet of

SEDIMENT DENSITY MEASUREMENT WITH

RADIOISOTOPES SEDIMENT DENSITOMETER

Date

Project

Personnel _________________________

Location

Surface elevation _________________

Depth to top of sediment __________

Depth of measurement ____________

Dosimeter number

Dosimeter readings:

Final _______________________

Initial _______________________

(1) Difference

(7) Water rate __________________

(8) Water correction (6)x(7) ____

(9) Sediment reading =(1)-(8) ____

(10) Sediment rate =(9)/(5) _______

Remarks:

Time:

(2) Into sediment _________________

(3) Out of sediment _______________

(4) Stop time ____________________

(5) Time in sediment =(3)-(2) _____

(6) Transit time (4)-(5) __________

(11) Intensity ratio, R=(10)/(7) _____

Wet density _______________________

Specific gravity __________________

Dry density _____________________

Q 22
with the sub-aqueous sampler and two by pushing a plastic tube into the bed

by hand.

Tables 1 and 2 summarize the results of the 23 samples. Note

that on R-22A and R-19B, the results for the 2-foot penetration for both

the RSD and SA samples compare very well. The results for the 6-foot

penetration do not compare though, the reason being that the RSD probe

measured the point density at 6-foot penetration, while the SA took a core

with the mir{rrium depth of 6 feet, which gave an integrated sample from

the surface of the sediment to 6-foot depth. It is interesting that the results from the 6-foot penetration with the RSD probe varied so much from

the smaller penetrations because in past reservoir work the smaller penetration core samples were used exclusively to give the density of the sedimenta. The RSD shows that the density of the sediments at the greater

depths is, in general, probably larger than has been realized in the past.

In the future, with further development of the RSD, it may be possible to

penetrate deeper into the sediments and learn more about the long time

compaction of the reservoir deposits.

The sediment size analysis curve of the 2-foot penetration Barnpies is given in Figure 10. The sample from R-22A is made up of the

finest particles as would be expected, since the sediment had to travel

through the entire reservoir before being deposited. By the same token,

the samples from R-9 and R-6 are the coarsest, because they are located

intheupperendofthereservoir. R-13, R-19B, R-1OB, andR-15, however, are fairly close to each other in particle size make-up, and do not

fall on the graph in the order of their progression downstream in the reservoir. This is very similar to the results found in the 1947 reaurvey,

23
where the range near the dam and those in the upper end of the reservoir

fell in their logical order on the size analysis curve while the in-between

ranges did not follow this sequence.

The correlation of density with the location of the sample in the

reservoir, and with depth of penetration, is given in Figure 11. Note that

as the penetration increases the density Increases in each case for a

specified range. There is a fairly uniform slope to each of these curves.

The correlation of density with the location of the sample in the reservoir

gives a relation similar to what may be expected; the sediment near the

dam being lightest, and the sands in the upper end of the reservoir being

the heaviest.

The average density of the sediment deposited in Guernsey Reservoir for the period from 1947 to 1957 was found to be 60.7 pounds per

cubic foot. The method of computation used was to divide the reservoir

into 6 segments and determine the acre-feet of deposition In each segment. Then the densities as determined by field measurements in each

of these segments was applied to the volume of deposition. The total tonnage of deposition in the reservoir thus determined. This total tonnage

was divided by the total volume of sediment deposited from 1947 to 1957

to arrive at the average density of 60.7 pounds per cubic foot.

24
Table 1

SIZE ANALYSES OF SEDIMENT SAMPLES FROM GUERNSEY RESERVOIR

North Platte River1 Wyoming

Pene- Dry Mecl-ianicai analysis

tra- den- Percent equal to or less than _____ ____ ____ _____

tion sity

_____

O.001

_____

0.002

_____

0.005

_____

0.009 0.019 0.037 0.074

_

0.149 0.297 0.589 1.19 2.38 4.76 9.52

Rn Sample (ft) lb/cu ft mm mm mm mm mm mm mm mm mm mm mm mm mm mm

22A 1 2.0 40.8 33 54 82 93

97

100 -- -- -- -- -- -- -- --

22A 1A 6.0 48.6 34 52 76 87 97 100 -- -- -- -- -- -- -- --

19B 2 2.0 59.6 22 32 45 57 74 89 99.5 100 -- -- -- -- -_

19B 2A 5. 0 71. 6 16 22 32 39 55 75 95 99. 5 100 -- -- -- -- --

15 3 1.7 70.0 24 32 45 54 71 91 99 99.8 100 -- -- -- -- --

15 3A 2.0 74.4 16 22 32 41 56 81 98 99.5 100 -- -- -- -- --

13 4 1.8 53.9 26 33 50 61 78 94 99 99.5 100 -- -- -- --

lOB 5 1.0 82.3 24 30 43 54 70 87 99 99.5 99.8 100 -- -- -- --

9 7 0.8 145.5 -- -- -- --

-- 2 4 14 62 90 95 97 g 100

6 6 0.5 142.7 -- -- -- --

-- i 2 2 3 31 67 89 99 100
Table 2

DENSITY OF SEDIMENT SAMPLES FROM GUERNSEY RESERVOIR

North Platte River, Wyoming

b3

0)

-- Sub-aqueous

sampler

Radioisotope

sediment densitometer

Field El Pene- Wet Dry Wet Dry

sample of sample tration density density density density Specific

Range No4 M. S.L. ft lb/cu ft lb/cu ft lb/cu ft lb/cu ft gravity**

R-22A 1 2.0 91.0 40.8 2.69

R-22A 1A 6.0 100.8 48.6 2.68

R-22A lB 4159.5 2.0 84 35

R-22A 1C 4159.5 6.0 123 98

R-20 12 4170.6 3.0 94 49

R-19B 2 2.0 106.5 59. 6 2. 65

R-19B 2A 5.0 115. 5 71. 6 2. 65

R-19B 2B 4180.8 2.0 104 66

R-18 11 4181.1 2.0 83 33

R-18 hA 4181.1 3.0 88 40

R-16 10 4185.6 2.0 91 44

R-15 3 1.7 112.4 70.0 2.64

R-15 3A 2.0 115.8 74.4 2.64

R-14 9 4192.9 2.0 77 22

R-14 9A 4192.9 3.0 88 39

R-13 4 18es 92,7 53.9 2.61

R-13 4B 4206.6 2.0 92 47

R-13 4C 4206.6 5.0 113 81

R-12 8 4204.5 2.0 98 58

R-1OB 5 1.0 122.7 82.3 2.64

R-1OB 5B 4211.0 2.0 104 67

*R-9 7 0. 8 167.4 145. 5 2.65

*R-6 6 0.5 1573 142.7 2.63

*These samples taken by pushing plastic tube into sediment.

**For RSD computations, the specific gravity was assumed at 2. 65.
Sediment Disposition in Guernsey Reservoir

Longitudinal Distribution

The variation of the thickness of the sediment deposition in

Guernsey Reservoir is presented graphically by Figure 12, page 49, The 1957

profile of the thaiweg is shown along with the 1937 and 1947 profiles, and

also the 1927 original thaiweg profile. The 1937 profile does not extend

all the way to the headwater of the reservoir because the resurvey was

not completed.

The thickest deposition of sediment is located at Range 18 where

it amounts to 37 feet. The 1947 resurvey showed that the thickest deposition was at Range 14 where it was 33 feet. Thus, it is shown that during

the 10-year period from 1947 to 1957 the tendency was for the sediment to

be deposited closer to the dam than during the previous period, the section

with the deepest sediment deposit having moved closer to the daro by 2.4

miles.

The 1947 longitud4nil profile shows a sharp break in grade of the

deposition at the entrance to the canyon. This was explained in the 1948

report with the statement, "It is believed that the greatest depth of sediment was deposited in the vicinity of Range 14 for the following reasons:

1, below this range the width of the lake narrows, restricting the flow of

the stream; 2, the drawdown of the lake has produced little or no current

below this range, based on the operation levels of the lake during irrigation seasons." The 1957 profile shows that this break In grade no longer

exists and that the slope of the sediment deposition Is more uniform

throughout the entire length of reservoir. This change in sediment disposition from 1947 to 1957 can be explained in part by the fact that Guernsey

27
Reservoir was operated for a six-year period at a lower than normal elevation. This six-year period started in 1951 and lasted through 1956. The

average month-end reservoir elevation during this six years was 4, 407. 49

feet. The twelve years preceding this period, 1939 through 1950, had an

average month-end reservoir elevation of 4, 411.26 feet. The yearly averages of the month-end elevations are:

Year Elevation Year Elevation

1939 4410.15 1948 4413.65

1940 4409.81 1949 4411.15

1941 4407.68 1950 4413.22

1942 4412.13 1951 4406.10

1943 4410.87 1952 4405.10

1944 4409.14 1953 4408.54

1945 4412.06 1954 4408.47

1946 4412.49 1955 4408.22

1947 4412.81 1956 4408.52

This lower operating level of the reservoir for a sustained period

of six years undoubtedly contributed to the fact that the sediment deposition

during 1947 to 1957 occurred closer to the dam than in the previous years

of operation. The other reason for this change in deposition pattern is

that the sediment in the upstream half of the reservoir has probably

reached a minimum slope based on sediment size and reservoir operation.

The 1947 slope was the same as the 1957 slope, 2.5 feet per mile. In

1937 the slope was 3.3 feet per mile, while the original slope of the river

channel was 5.7 feet per mile. It can be expected that the future sediment

accumulation will continue to build up the portion of the reservoir near the

dam till the slope of the thalweg is 2.5 feet per mile throughout nearly the

entire Fength of the reservoir. The power intake sill will, of course, always provide a control and therefore the sediment will slope uniformily to

perhaps Range 20 where it will then break its grade and slope towards the

28
power intake sill. The ratio between the present sediment slope and the

original river channel slope is 2. 5 feet/mile = . .

5.7 feet/mile

Lateral Distribution

The lateral distribution of the sediment in Guernsey Reservoir

is shown by Figure 131 page 51.

Range 21 is typical of the deposition in the canyon-like portion

of the reservoir near the dam • The sediment is equally distributed over

the bottom forming a very flat surface. Range 15 is typical of the lake

portion of the reservoir where a channel is always found which is a result

of the drawdown of the reservoir. Except for the channel, the sediment

is laid down fairly uniformly in layers which form a flat bottom. Ranges

5 and 8 are typical of the head of the reservoir. Ranges 5 and 8 cross

sections are similar to what one would expect to find in an aggrading

river channel. Actually, most of the year this portion of the reservoir

does not experience the effects of the reservoir storage and it usually

functions as a river channel would.

The lateral distribution of the sediment, at the sections where

there are creeks tributary to the reservoir, changes from the typical

cross section shown. At these points the sediment brought in by the

reservoir tributaries drops out and deltas are formed at their mouths.

This is probably the greatest factor causing the 4420-foot contour area

of the reservoir to diminish as the years pass.

Sediment Disposition Curves

The 1947 and 1957 sediment disposition curves are shown in

Figure 14, page 53. The curves illustrate clearly that during the 1947-

1957 period the sediment was deposited in a greater percent in thelower

elevations of the reservoir which are found towards the dam.

29
In the period that Guernsey Dam was planned and designed, there

was no procedure for forecasting the shape of the sediment disposition

curve. The original data pertaining to the depth and capacity of the reservoir were used in this present investigation to determine, if a forecast

had been made, if it would match the actual sediment disposition curve.

The relation between capacity and depth indicated that a Va&t Hul Type

III curve should be used up to a 40-foot depth, and from 40 feet to the surface a Type II should be used. This particular reservoir is an excellent

example, however, as to why engineering judgment must be used on forecasting disposition of sediments rather than only applying empirical methods. The Sediment Disposition Curves in Figure 14 show that the sediment

was deposited closer to a Van't Hul Type I curve than to a Type II or III.

The reason for this is that the portion of the lake between Ranges 15 and 10

acted as a huge stilling basin and the amount of deposition that occurred

here was abnormally large when based upon the depth-capacity relationship. Had a sediment disposition forecast been made for this reservoir,

it would have been necessary to consider the effect of the lake

storage on the disposition plus the narrow neck near Range 15, and several

other factors peculiar to this reservoir. The factors are itemized in the

"Interim Report, Distribution of Sediment in Reservoirs" published in June

1954 by the Bureau of Reclamation.

Area-Capacity Curves

The 1927, 1947, and 1957 area and capacity curves are presented

in Figure 15, page 55. An area and capacity tabl. is given in Table 3,

page 32.
The capacity curves illustrate clearly the large loss of storage

in Guernsey Reservoir between 1927 and 1947 when compared with the penod from 1947 to 1957. The loss in capacity for the first 20 years was

nearly 25, 000 acre-feet, while in the last 10 years it was only 4, 350 acrefeet.

The loss of area at the 4420 contour indicates only a very small

loss of 19 acres in the first 20 years, and 4 acres in the last 10 years of

Guernsey Reservoir operation for a thirty year loss of area of 23 acres.

The area curves, however, show loss of area at all of the contours. The

area loss at contour 4395 amounts to nearly 900 acres for the 30-year penod. The area curves also show that the reservoir has completely been

filled in with sediment from elevation 4,329 feet to 4,359 feet. The capacity

in this 30-foot vertical interval amounted to 2, 900 acre-feet.

At the present time the sediment deposit is up to the sill of the

power intake. This means that water passing through the turbines has,

and will continue to have, a large concentration of silt and clay which of

course causes abnormal wear on the blades of the turbine wheels.

Sediment Distribution by Segments

The reservoir was divided into six segments to facilitate the cornputation of the total tonnage of sediment deposited in the reservoir during

the period from 1947 to 1957.

Information on the deposition within these segments is given in

Table 4, page 33.

A comparison of the sediment deposited during the 1927 to 1947

period and the 1947 to 1957 period is given in Table 5, page 34.

31
Table 3

AREA-CAPACITY TABLE

Guernsey Reservoir

Contour

line

el

Capacity

1927

acre-ft

Capacity

1947

- acre-ft

Capacity

1957

acre-ft

Area

1927

acres

Area

1947

acres

Area

1957

acres

4,420 73,810 49,150 44,800 2,405 2,386 2,382

4,415 62,250 37,770 33,540 2,208 2,159 2,122

4, 410 51, 730 27, 680 23, 680 1, 994 1, 874 1, 822

4,405 42,240 19,570 15,775 1,797 1,376 1,340

4,400 33,690 13,790 10,315 1,618 948 844

4,395 26,110 10,050 6,905 1,409 561 520

4, 390 19, 850 7, 588 4, 800 1,098 425 322

4,385 14,920 5,650 3,360 873 350 254

4,380 11,060 4,052 2,215 671 289 204

4,375 8,069 2,726 1,320 528 242 154

4,370 5,765 1,647 660 395 190 110

4,365 4,066 802 200 286 148 74

4, 360 2, 834 189 2 207 99 5

4,355 1,910 0.6 0 162 1.( 0

4,350 1,192 0 0 125 0 0

4,345 639 0 0 96 0 0

4,340 278 0 0 50 0 0

4,335 92 0 0 25 0 0

4,330 19 0 0 6 0 0

4,329 4 0 0 1 0 0

32
Table 4

Sediment Distribution by Segments - 1947-1957

C..,

Segment

Capacity

1947

acre-feet

Capacity

1957

acre-feet

Sediment deposited

1947-1957

acre-feet

Density of

sediment

lbs/cu ft

Sediment deposited

1947-1957

tons

Head of reservoir

to Range lOB 3,047 2,797 250 144.1 784,625

Range lOB to Range 12 3, 556 3,629 * -73 69.1 * -110, 166

Range 12 to Range 15A 22, 073 20, 605 1, 468 52. 1 1, 665, 795

Range 15A to Range 19B 5, 225 4, 016 1, 209 57. 3 1, 508, 326

Range 19B to Range 21 8,801 7,645 1,156 61.1 1,538,356

Range 21 to Dam 6, 448 6, 108 340 48. 6 360, 634

49,150 44,800 4,350 5,74757O

*This represents scour of sediment which was deposited elsewhere in the reservoir.

Average density of sediment, arrived at by dividing total tonnage by total acre-feet of sediment deposited in the 10-year period, is 60.7 lb per cu ft.
Table 5

1927 to 1957 Sediment Distribution by Segments

Segment

Capacity

1927

acre-feet

Capacity

1947

acre-feet

Capacity

1957

acre-feet

Deposition

1927-1947

acre-feet

Deposition

1947-1957

acre-feet

Deposition

1927-1957

acre-feet

Head of reservoir

to Range lOB 6, 525 3, 047 2, 797 3, 478 250 3, 728

Range lOB to Range 12 7, 111 3, 556 3, 629 3, 555 * -73 3, 482

Range 12 to Range 15A 35, 442 22, 073 20, 605 13, 369 1, 468 14, 837

Range iSA to Range 19B 7, 256 5, 225 4, 016 2, 031 1, 209 3, 240

Range 19B to Range 21 10, 405 8, 801 7, 645 1, 604 1, 156 2, 760

Range 21 to Dam 7,071 6, 448 6, 108 623 340 963

73,810 49,150 44,800 24,660 4,350 29,010

*This represents scour of sediment which was deposited elsewhere in the reservoir.
STATISTICAL SUMMARY

Guernsey Reservoir

Age 30 years

Watershed

Total area, 1927 to 1938 5,500 sq ml (1)

Total area, 1938 to 1957 5,400 sqmi (2)

Reservoir

Area at crest stage, 1927 2,405 acres

Area at crest stage, 1947 2,386 acres

Area at crest stage, 1957 2,382 acres

Storage capacity, 1927 73,810 acre-feet

Storage capacity,: 1947 49,150 acre-feet

Storage capacity, 1957 44,800 acre-feet

Storage per sq ml of drainage area, 13.42 acre-ft/sq ml

1927

Storage per sq mi of drainage area, 9. 10 acre-ft/sq mi

1947

Storage per sq ml of drainage area, 8. 30 acre-ft/sq mi

1957

Sedimentation

Sediment accumulated, 1927-1947 24,660 acre-ft

Sediment accumulated, 1947-1957 4,350 acre-ft •0

Sediment accumulated, 1927-1947 28,580,000 tons

Sediment accumulated, 1947-1957 5, 748, 000 tons

Sediment* yield, 1927-1947 0.23 acre-ft/sq mi/yr

Sediment* yield, 1947-1957 0.08 acre-ft/sq mi/yr

Depletion of Storage

Yearly loss of original capacity, 1.67% per year

1927-1947

Yearly loss of original capacity, 0. 59% per year

1947-195 7

Yearly loss of original capacity, 1.31%

1927-1957

Loss of original capacity, 1927-1947 33.41%

Loss of original capacity, 1947-1957 5.90%

Total loss of original capacity, 39. 31%

1927-1957

*Does not include the sediment passing Guernsey Dam. Please

see section on Trap Efficiency..

(1) Area between Pathfinder Dam and Guernsey Dam.

(2) Area between Alcova Dam and Guernsey Dam.

35
Trap Efficiency

The Geological Survey took suspended sediment measurements

below Guernsey Dam during the period from April 1947 through the 1952

water year. The gaging station that was used is located about 31 4 mile

below the dam, and because of its proximity to the dam, it can be assumed that the suspended sediment measured at this station is that which

passed through the reservoir.

From July 20, 1947, to September 30, 1952, the USGS measured

208, 500 tons of suspended sediment discharged from Guernsey Reservoir.

From October 1, 1952, to July 20, 1957, the suspended sediment discharge was estimated using the relationship between water and sediment established in the 1947 to 1952 measurements. It was thus determined that

288,000 tons of suspended sediment was discharged from Guernsey Reservoir during the 10-year period between the 1947 and 1957 resurveys.

It has previously been stated in this report that the same 10-year

deposition in Guernsey Reservoir was 5,747,570 tons.

Therefore:

5, 747, 570 Trap Efficiency =5747,57p+ 2ff8,ooo = 95.2%

This is the average trap efficiency for the reservoir from

1947 to 1957.

This trap efficiency was checked using USGS suspended sediment

measurements at Cassa, Wyoming, which is upstream from Guernsey

Reservoir a short distance. Over a 5.2-year period of records (1947-

1952), it was shown that 4, 616, 500 tone of sediment entered Guernsey

Reservoir and 208, 500 tons were discharged past the dam. From this

data, the trap efficiency was shown to be 95.5 percent. This close

36
agreement substantiates the 10-year trap efficiency of 95. 2 percent which

was calculated on the basis of sediment actually deposited, and that measured downstream from the reservoir.

The volume of the sediment which was passed through Guernsey

Reservoir amounted to 275 acre-feet. This figure is based upon the density of the sediments as deposited near the dam at Range 22A.

Channel Condition Below Guernsey Dam

The channel downstream from Guernsey Dam has in general aggraded between 1953 and 1957. This is shown in the cross-sections in

Figure 16, page 57. At one section, the Geological Survey Gaging Station,

the cross-section is plotted for 1947 as well as 1953 and 1957. This section shows aggradation since 1947 as well as from 1953. The location of

the sections* shown in the figure are as follows:

Section 11--1,425 feet below end of spillway chute

Section 12- -1, 765 feet below end of spiliway chute

Section 17--4, 150 feet below end of spillway chute

USGS Station- -5, 368 feet below end of spillway chute

Section 11 is on a river bend and since 1953 there has been a redistribution of the bed material so that the deepest portion of the channel

has moved from the center to the outside bend. This section has neither

*

degraded or aggraded but has remained relatively stable.

*It was impossible to locate 2 of the sections used in the 1947

resurvey. These sections were Range 0.5 and 0.9 as described on page

16 of Reference 3.

37
Section 12 is on the same river bend as Section 11. This section

shows an average of about 0.7 foot of aggradation since 1953. Both Sections 11 and 12 are upstream from Sunrise Creek which is the only tributary in this reach of the river. Therefore, the aggradation at Section 12

probably originated from a gravel groin constructed in the taiLrace near

the powerhouse.

Section 17 aggraded approximately 2 feet between 1953 and 1957.

Since this section is downstream from Sunrise Creek, the aggradatlon material is undoubtedly gravels contributed by Sunrise Creek. The lower discharges of the recent years has not been sufficient to transport the bed

load as it has in the first 20-year period.

The USGS Gaging Station aggraded approximately 1 foot between

1947 and 1953. Some aggradation also occurred between 1953 and 1957.

This aggradation, as at Section 17, originated from sediment contributed

by Sunrise Creek.

The period from 1953 to 1957, and from 1947 to 1957 for the

gaging station, resulted in general aggradation of the channel below

Guernsey Dam. However, the long-time result, from 1927 to 1957, is

that of degradation. The 1957 condition, even with the recent aggradation, shows a net degrading of 1 to 2 feet at Sections 11 and 12, and about

3 feet at Section 17 and the gaging station.

Future Sediment Deposition in Guernsey Reservoir

The construction of Glendo Dam will decrease the deposition -

rate in Guernsey Reservoir a substantial amount. The sediment contributing area of the drainage basin will be reduced from 5,400 square miles

to about 700 square miles, which is about 13 percent of the pre-Glendo area.

38
The 1927 to 1957 average deposition rate in Guernsey Reservoir

has been about 970 acre-feet per year, or a yearly loss of 1.31 percent

of the original storage capacity of 73, 810 acre-feet.

To make an estimate of the future sedimentation rate, a soil erosion map was examined of the past and present area of the Guernsey drainage basin. Erosion severity areas were planimetered and the following

was determined as shown in the table.

Soil condition

Minor erosion

Moderate sheet

erosion

Severe sheet

erosion

Severe erosion with

geologic erosion

pre dominant

Soil Erosion Areas

Drainage area

Before Glendo After Glendo

5,400 sguare miles 700 square miles

12 percent 24 percent

78 percent

8 percent

2 percent

55 percent

21 jrcent

o percent

100 percent 100 percent

The condition of the soils in the two areas with respect to the

severity of erosion can be expected to give about equal sediment contributions per square mile. The fact that one basin is smaller means

that the sediment yield which actually reaches Guernsey Reservoir will be

higher for the 700-square mile basin than for the 5,400-square mile basin.

It has been shown that as the drainage basin increases in size, the sediment yield decreases, when other factors are equal.

39
The sediment yield for the 5)400 square miles over the period

from 1927 to 1957 was 212 tons/square mile/year. Using the relationship

as developed by Glymph in Reference 6, the sediment yield for the

700-square mile basin is 290 tons/square mile/year. Based on the average

density of 60.7 pounds/cubic feet of the deposited sediment, the average

yearly reservoir deposition will be 150 acre-feet/year.

Summary

Guernsey Reservoir has been subject to an unusually high sedimentation rate during its 30-year life up to 1957. This is due primarily

to the fact that the capacity is smaU when compared to the large size of

the drainage basin.

In the period from 1927 to 1957, Guernsey Reservoir lost 39.3

percent of its original capacity to sediment deposition. The 10-year period form 1947 to 1957, however, was a period of reduced storage loss.

From 1927 to 1947 the loss was 1.67 percent per year while the 1947 to

1957 loss was only 0.59 percent per year. This difference in loss rate

was due primarily to reduced reservoir inflow during the latter 10 years.

This dry period was the cause of two contributing factors to a relatively

smaU capacity loss during the last 10-year period. One factor was that

less sediment was carried by the North Platte River above Guernsey Reservoir and thus there was less sediment available for deposition. The

other factor was the low operating level of the reservoir from 1951

through 1956 which caused the deposited sediments to be exposed to the

sun and air more than normal. This exposure caused the sediments to

compact so that they occupied less reservoir space than an equivalent

deposition during the 1927 to 1947 period.

40
The pattern of disposition of the sediments within the reservoir

has changed so that during the last 10 years the deposition has occurred

much closer to the dam than in the previous years. This is due to the

lower operation level of the reservoir, and the fact that a stable slope of

the sediments has been established in the topset bed of the reservoir. The

slope of the sediments here has reached 2. 5 feet per mile.

The density of the last 10 years of sediment deposition averages

out to be 60.7 lb/cu ft. The density as found in the 1947 resurvey was

53. 2 lb/cu ft. This Increase is due, as mentioned above, to the sediments hav

ing been exposed to air and sun during the period of low reservoir operation.

The trap efficiency of Guernsey Reservoir for the period from

1947 to 1957 was 95.2 percent. The 1927-1947 trap efficiency reported in

Reference 3 waa calculated to be 92.2 percent for Guernsey Reservoir.

This lower trap efficiency is explained by the fact that it was based on only

6 months of sediment measurements below Guernsey Darn, and these particular 6 months had unusually high sediment discharges from Gu*rnaey Dam.

The channel below Guernsey Darn has aggraded in recent years,

though the 1927 to 1957 result has been a net degradation of from 1 to 3

feet.

The storage loss to Guernsey Reservoir has been very large in

past years. The construction of Glendo Dam, however, has reduced the

sediment contributing area to Guernsey Reservoir from 5,400 square

miles to' 700 square miles. This reduction of sediment contributing area

will, therefore, reduce the future sediment inflow to Guernsey Reservoir from the historic 970 acre-feet/year to about 150 'acre-feet/year.

The construction of Glendo Dam has, therefore, extended the useful

life of Guernsey Reservoir by many years.

41
ACKNOWLEDGMENT

The preparation of this report and the data analysis herein were

performed by Kenneth R. Wright, Hydraulic Engineer, Sedimentation

Section, Hydrology Branch, Division of Project Investigations. Mr.

Wright also served as technical supervisor In the acquisition of the

field data.

The report was reviewed by Whitney M. Borland, Head, Sedimentation Section. Acknowledgment is also made to Messrs. J. R. Biter

and H. P. Dugan, Chief and Assistant Chief, respectively, of the Division of Project Investigations and Herbert S. Riesbol, Chief, Hydrology

Branch, for their review of this report.

An able surveying crew from the Casper Project Office under

the direction of Messrs. John Larsen and J. L. Rowse is to be commended for its fine performance of the field work. Preliminary field

work by Messrs. C. R. Miller and H. W. Ford, from the Sedimentation

Section, Hydrology Branch, and Casper Project Office, respectively,

was invaluable to the later portion of the reaurvey. Messrs. Anker and

Schultz who are stationed at Guernsey Dam were very helpful in furnishing Information and services in regard to the resurvey,

Mr. Q. L. Florey of the Chemical Engineering Branch, Engineering Laboratories Division, supervised the Radioisotope Sediment

Densitometer sampling and assisted Messrs. C. R. Miller and K. R.

Wright In taking samples of reservoir deposits with the Sub-Aqueous

Sampler.

The Project Office at Casper performed the tedious job of interpreting the depth recorder charts, drawing new reservoir topography

42
maps, and computing new area-capacity tables. The Casper Project

Office is commended for their rapid, neat, and accurate work on this

portion of the resurvey.

The reHurvey was performed at the request of Region 7 of the

Bureau of Reclamation, R. J. Walter, Jr., Regional Director.

43
Bibliography

1. Water Supply Papers, Surface Water of the United States, Part 6,

Missouri River Basin, Geological Survey, United States Department

of the Interior

2. Water Supply Papers, Quality of Surface Water Supply of the United

States, Part 6, Missouri River Basin, Geological Survey, United

States Department of the Interior

3. Sedimentation Survey of Guernsey Reservoir, North Platte Project,

Wyoming and Nebraska, Sedimentation Section Report, Hydrology

Division, Bureau of Reclamation, United States Department of the

Interior; November, 1948

4. Density Measurement of Saturated Submersed Sediments by Gamma

Ray Scattering, Chemical Engineering Laboratories, United States

Department of the Interior; March, ,1.957

5. Interim Report Distribution of Sediment in Reservoirs, Hydrology

Branch, Project Investigation Division, Bureau of Reclamation,

United States Department of the Interior; June, 1954

6. Relation of Sedimentation to Accelerated Erosion in the Missouri

River Basin, Louis M. Glymph, Jr., Soil Conservation Service,

United States Department of Agriculture

7. Determination of Location and Rate of Growth of Delta Formations,

Lloyd C. Fowler, United States Army Engineer Division, Missouri

River, Corps of Engineers

44
INCHES

----------

----------------

---------------

w

-J

-A

U,

I2

Ui

0

Ui

0

c'J $, - )

q o 0

'9 ci p

0 0

PARTICLE SIZE - MILLIMETERS

CLAY SILT

I

SAND I GRAVEL

I Medium Coarse Vary Fine Fine Medium Coarse Very Fine Fine Medium j Coarse Very Coarse Very Fine Fine Med.

AMERICAN GEOPHYSICAL UNION ( A.G.U.) CLASSIFICATION

SIZE ANALYSIS OF SEDIMENT SAMPLES

TAKEN WITH 2 FOOT PENETRATION

Ui

1

Iz

LU

0

Ui

0

- J_JLJu !•!!!!!!•

0 0 0 000000

4 e) I. ) w

LAN/TED ST4 rES

DEPARrMENT rHE IN1ER/OR

8URE4L/ OF RECLAMATION

SEDIMENT SIZE ANALYSIS

GUERNSEY RESERVOIR

NORTH PLATTE RIVER

.

JULY,1957

OR4_._ MJ SUBMITTED

TR4CED qccii&oto

0,CxEO APPROVED

I

cquoo 4Q. q;/947

45 Figure 10.

U.S_ STANDARD SIEVE SIZES
tOO

90

80

70

60

50

4C

20

20

/ S

__

I U) >

________ _________ ________ ________ ________________

-Ui-

+ I

/

Density- Distance

+ RSD Samples I-

+ • Sub-Aqueous Samba

Density- Penetration

2

-

^

J

1

o Range-,4

-

I-.

U-

+ o Range -22-A /1 A

/ -

a>

o I

Ic Ui

-I

'

U,

Ui

____ _____ _______ _____ _______

U -

-w _____ ____ -0

2

Iii 0

z

Ui 1

1^ Ui

0

-

__p

//

__tx/i ________ ____ ____

,-Oensity vs. Distance from

upper end th petrat ion 0

/ / up to 3 feet

ill

q, / /

____ ____

_ ____ ____

/

U)

d' *

.

I

' I 'S I

Density vs. Penetration

A ll samples with RSD

DRY ENSTY LSS./CU.VT.

40 60 80 (00 (20 40 (50

NORTH PLATTE RIVER

GUERNSEY RESERVOIR

CORRELATION OF DEPTH WITH

LOCATION AND PENETRATION OF SEDIMENT SA MPLES








h

r

at."

0

\

NOTE

P., 0.?,. -. 9k..? I

'P

-

00 PLATTE P0T.wfl%WSI

EN TATIOI SU$07 NVERNSEY RESERVOI

NO,PTN PLATTE NIEER-PLATTE CEUNTP lfl

totmots Ifla?? MAT 7-J0tE PS 957

GPO &5636

\\\\\\\\\\\\\

- - -- -- -- - - - - - -

EXPLANATION

-- 5*0,. c... 01 L.a.

-

-_-----05..- ItT-S Pt On,.., Mt.,,.?

-

- mOltS O1 51,0..

4 - floLo-0 0-909 5*0 li,nt.tI.. np.

- -

Ph. T,.n.a. S?s,IPS I47

L---------- -

-

J000 S TtICflaIS??MO S?.?Ioc 1947

65 Figure 18. Sheet 2 of 2.