Effects of Land Use and 

Retention Practices on 

Sediment Yields in the 

Stony Brook Basin, 

New Jersey

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1798-L

Prepared in cooperation with the 

New Jersey State Departments of 

Environmental Protection and 

of Agriculture
Effects of Land Use and 

Retention Practices on 

Sediment Yields in the 

Stony Brook Basin, 

New Jersey

By LAWRENCE J. MANSUE and PETER W. ANDERSON

SEDIMENTATION IN SMALL DRAINAGE BASINS

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1798-L

Prepared in cooperation with the 

New Jersey State Departments of 

Environmental Protection and 

of Agriculture

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1974
UNITED STATES DEPARTMENT OF THE INTERIC ^ 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 74-600007

For sale by the Superintendent of Documents, U.S. Government Print; »xg Office

Washington, D.C. 20402 Price 55 cents (paper cover)

Stock Number 2401-02465
CONTENTS

Page

Abstract ___ LI

Introduction __ _ 1

Previous investigations _ 3

Acknowledgments _ 4

Stony Brook basin _ 5

Physiography _ 5

Land use 8

Sedimentation - 9

Stony Brook at Princeton 10

Multiple-regression analysis ___ 12

Double-mass-curve analysis _ 18

Subbasin-sediment yield _ ___ 21

Sediment-retention reservoirs __ 23

Sediment-particle size _ 25

Chemical quality _ _ _ 28

Summary and conclusions _____ _ _ _ 30

References ____ 32

ILLUSTRATIONS

Page

FIGURE 1. Map of the upper Millstone River basin L5 

2. Generalized geologic map of the Stony Brook basin 7 

3-8. Graph showing 

3. Frequency distribution of mean daily streamflow, suspended-sediment concentration, and 

suspended-sediment discharge, Stony Brook _ 11

4. Trend analysis of streamflow and sediment discharge, Stony Brook __ 12

5. A representative storm hydrograph, Stony

Brook .___ 15

6. Suspended-sediment transport curve, Stony

Brook __________ 17

7. Double-mass relation of runoff and sediment

discharge, Stony Brook 19

8. Double-mass relation of observed and calculated

sediment concentrations, Stony Brook 20 

9. Map showing location of subbasin sampling stations and

sediment-retention reservoirs _ 21

10. Graphs showing sediment-load relation between subbasin sampling stations and Stony Brook at Princeton 22

11. Graph showing particle-size distribution of suspended

sediment, Stony Brook 26

ill
IV CONTENTS

TABLES

Page

TABLE 1. Average annual and normal precipitation at Trenton and 

in the State's northern and southern climatologh divisions _______________________________ L6

2. Land use in the Stony Brook basin and selected subbasins_ 8

3. Suspended-sediment discharges, Stony Brook at Princeton _ 13

4. Annual suspended-sediment discharge of Stony Brook subbasins ______________________________ 23

5. Descriptive data on retention reservoirs _ _ 24

6. Suspended-sediment discharges, Baldwin Creek at Ealdwin

Lake, near Pennington _____ ___ 25

7. Particle-size distribution of sediments deposited in Carnegie Lake __________________ _..____ 27

8. Pesticide analyses of water and bed samples collected from

Stony Brook and Carnegie Lake -___ __.._._ 29
SEDIMENTATION IN SMALL DRAINAGE BASINS

EFFECTS OF LAND USE AND RETENTION

PRACTICES ON SEDIMENT YIELDS IN THE

STONY BROOK BASIN, NEW JERSEY

By LAWRENCE J. MANSUE and PETER W. ANDERSON

ABSTRACT

The average annual rate of suspended-sediment discharge of the Stony 

Brook at Princeton, N.J. (44.5 square miles) is about 8,800 tons, or 20? tons 

per square mile. Annual yields within the basin, which is in the Piedmont 

Lowlands section of the Piedmont physiographic province in west-central 

New Jersey, range from 25 to 400 tons per square mile. Storm runoff that 

transports suspended materials in excess of a ton carries 90 percent of the 

total suspended-sediment discharge from the basin. Observations of particlesize distributions indicate that the suspended material carried during storms 

is 55 percent silt, 40 percent clay, and 5 percent sand.

A trend analysis of sediment records collected at Princeton betweer 1956 

and 1970 indicated an increase in suspended-sediment discharge per unit of 

water discharge during 1956-61. From early 1962 to late 1967, sediment 

trends were difficult to interpret owing to complicating factors, such as reservoir construction, urbanization, and extreme drought. After 1967, yields 

decreased.

Variations in sediment yields during the study are attributed to the integrated influence of several factors. A 2.9 percent decrease in croplands and 

an increase of 5.1 percent in idle and urban land use probably produced a 

net increase in sediment yields. Construction of seven sediment-retention 

reservoirs under Public Law 566 resulted in temporary increases ir sediment yields. However, based on a trap-efficiency investigation at 1 site, the 

combined effect of operation of these 7 reservoirs is estimated to rerult in 

a 20 percent reduction in sediment discharge from the basin. Other factors 

that influence the noted decrease include reduction in yields during 5 years 

of drought, 1962-66, and reduced construction and development during the 

latter part of the study period resulting from a general economic slovdown.

INTRODUCTION

Sediment is an important but often overlooked aspect of stream 

quality. It degrades water quality for nearly every water use. 

Sediment affects the heat balance in streams, shades out aquatic 

plants, abrades constructions in stream channels, and interferes

Li
L2 SEDIMENTATION IN SMALL DRAINAGE BASINS

with the life process of aquatic organisms. Deposited in channels, lakes, reservoirs, ditches, or pipelines, sediment reduces storage and transport capacity, smothers bottom organisms, and 

changes the aquatic habitat. In flooded areas, it may severely damage buildings and their contents, crops, highways, drainage 

ditches, and other land features. In highly industrialized and 

urban areas, sediment may carry surface-adsorbed nutrient materials, pesticides and other toxins, or pathogenic micro-organisms.

As part of its continuing evaluation of the Nation's water resources, the U.S. Geological Survey has cooperated with several 

State and Federal agencies in the investigation of stream-sedimentation characteristics in New Jersey. The purpore of this report is to present the findings of one such investigation on the 

Stony Brook basin in west-central New Jersey.

The original objective of the investigation was to determine the 

suspended-sediment load transported from the basin into Carnegie 

Lake. In order to meet this objective, daily measurements of 

suspended-sediment concentration were made at Princeton. On the 

basis of these measurements and daily water-dischrrge records, 

daily, monthly, and annual loads of suspended sediment to the 

lake were computed.

The objective was modified shortly after inception cf the project 

to include an investigation of the basin's hydrology in relation to 

land-use and land-management practices. Special emphasis in the 

modified investigation was placed on the influence and efficiency 

of reservoir development by the U.S. Soil Conservation Service 

(USSCS) under Public Law 566 (P.L. 566) in reducing sediment 

yield from the basin. Measurements of sediment discharge at 

Princeton in the modified project were to define lonjr-term variations in sediment yield due to gradual urbanization in the basin 

and to the construction of several P.L. 566 reservoirs. Periodic 

measurements of sediment concentrations at five subbasin sampling sites were made during storms to define the yields from 

these areas.

Daily sediment-discharge records were collected f~om the outfall of one P.L. 566 retention reservoir, Baldwir Lake near 

Pennington. These records and periodic measures of the changes 

in the reservoir capacity were used to determine its trap efficiency.

In addition to sediment analyses, additional samples were randomly collected and analyzed for chemical constituents at most of 

the sampling sites. A brief discussion of the results of these 

analyses is presented at the end of this report.
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L3

All records collected during the project were published annually 

in the Geological Survey's Water-Supply Paper series titled 

"Quality of Surface Water in the United States." In addition, 

since 1964 the records also have been released in annual b*.sicdata releases titled "Water Resources Data for New Jersey Part 

2. Water Quality Records." Distribution of these latter reports is 

limited as they are designed primarily for rapid release of data 

to meet local needs.

PREVIOUS INVESTIGATIONS

In 1956, several local agencies, including the Mercer and Hunterdon County Soil Conservation Districts and the Stony BrookMillstone Watersheds Association requested assistance through 

the USSCS under the Watershed Protection and Flood Prevention 

Act (P.L. 566). Detailed improvements were suggested to control 

sedimentation and flooding in the Stony Brook basin. Subsequently, a watershed plan was prepared for the construction of 

nine P.L. 566 reservoirs, for channel improvements, and for other 

conservation practices in the basin. Implementation of this plan, 

that since has been revised or modified several times, was b^gun 

in 1956.

Recognizing the needs for information to define the long-term 

effects of the work plan, this cooperative investigation of sedimentation in the basin was begun in 1956 by the predecessor 

of the present New Jersey State Department of Environmental 

Protection, Division of Water Resources, and the U.S. GeolcTical 

Survey, at the request of Princeton University and the f tony 

Brook-Millstone Watersheds Association. During 1962-67, funding for the cooperative project was provided by the State Department of Agriculture, State Soil Conservation Committee. Subsequently, the Division of Water Resources returned as the prir?.ipal 

cooperating agency. Preliminary results of the cooperative investigation between the State and the U.S. Geological Survey, in 

addition to the annual publication of basic data, were reported by 

George (1963), Anderson and George (1966), Anderson anc1 McCall (1968), and Mansue (1970).

George summarized results from the period 1956-59 and made 

preliminary observations on sediment transport by streams in the 

basin. He reported that the greater part of annual suspendedsediment discharges occur during the nongrowing season. Soil 

conservationists concluded from this fact that more efficient covercrop practices were needed to reduce soil erosion from farmlands 

during nonproductive periods. George also concluded that urban
L4 SEDIMENTATION IN SMALL DRAINAGE BASINS

expansion and reservoir construction produced Hgher-thanaverage suspended-sediment yields in the basin between 1956 and 

1959. He inferred that land-use changes that exposed soils created temporary conditions contributing to excessive stream sedimentation. George also reported that on several occasions construction of bridges, reservoirs, or pipelines in or near the stream 

channel contributed to temporarily high sediment yields in this 

basin. This trend toward increased sediment yield in the basin 

from urbanization and construction was shown by George (1963, 

p. 42) to expand after 1957. That is, the amount of sediment for 

a given rate of runoff increased significantly.

Anderson and McCall (1968) included a brief discussion of this 

project in an article on urbanization's effect on sediment yields in 

the State. Mansue (1970) more recently discussed sediment yields 

in the Stony Brook basin, as affected by land-use and retention 

practices. In addition, Anderson and George (1966, p 37-40), as 

part of a reconnaissance of the water-quality characteristics of 

New Jersey's streams, presented brief discussions of the sediment 

characteristics of this basin.

ACKNOWLEDGMENTS

The authors acknowledge the guidance, support, and advice 

received from the following persons, without whose assistance the 

study could not have been accomplished: Mr. Phillip Alampi, Secretary, State Department of Agriculture; Mr. C. M. Pike, Director, State Division of Water Resources; Messrs. G. F. Walton, 

M. W. Crooks, and S. R. Race, successive Executive Secretaries 

of the State Soil Conservation Committee, and Mr. G. R. Shanklin, former Director and Chief Engineer, State Division of Water 

Policy and Supply.

Appreciation is acknowledged to representatives of the Stony 

Brook-Millstone River Watersheds Association, in particular, Paul 

M. Van Wegen, former President, and M. W. Crooks, G. F. Walton, R. W. Thorsell, and I. R. Walker, successive Executive Directors, for their advice, support, and guidance in the conduct of 

the project and for their assistance in coordinating the services 

of several resident observers throughout the watershed.

The technical staff of the U.S. Soil Conservation Service, in 

particular, S. L. Tinsley, R. W. Akely, and W. J. Parker, successive State Conservationists, and K. T. Werkman, State Engineer, 

and H. R. Slayback, District Conservationist, assisted1 most effectively in the planning and scheduling of activities.
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L5

STONY BROOK BASIN

The Stony Brook is a major headwater tributary of th<^ Millstone River. It drains 47.8 sq mi (square miles) and flovrs into 

Carnegie Lake near the east edge of Princeton (fig. 1).

This part of New Jersey has a fairly mild climate. Based on 

National Weather Service records for Trenton, the nearest city 

having continuous climatologic records, while winter temperatures may occasionally drop to 0°F ( 17.8° Celcius), the average 

daily temperature during the coldest month, January, is 33°P 

(0.6°C). The average daily temperature in July, the warmest 

month, is 76°F (24.4°C). The growing season ranges from 190 

to 240 days and averages 218 days. Distribution of precipitation 

throughout the watershed seems nearly uniform, both in time and 

place. For comparison, a tabulation of average precipitation during 1956-70 and the normal monthly and annual precipitation in 

the State's northern and southern climatologic divisions f.nd for 

Trenton are presented in table 1. The basin is in the boundary 

area between the two divisions.

PHYSIOGRAPHY

The basin lies on the east edge of the Piedmont Lowland section 

of the Piedmont physiographic province (fig. 1). Andersin and

EXPLANATION

Gaging station 

 "^ Generalized fall line 

 Basin boundary

FIGURE 1. Map of upper Millstone River basin showing generalized physiographic boundary.
L6 SEDIMENTATION IN SMALL DRAINAGE BASIN?

TABLE 1. Average annual and normal precipitation, in inches, at Trenton 

and in the State's northern and southern climatologic divisions

[Based on National Weather Service records]

Year

1966 __ _ _

1967

1968 ____________ .

1969 _ __ _ __

I960 _ . _ _

1961 _ ___ _______ _________

1962 _ ___ __ __

1963 _ _ _

1964 ______________________

1966 _ __ _ __ _

1966 _ - -

1967 _______ ____ __

1968 _ _- - _ _

1969

1970 _ ___________ __

Trenton

Average

to ae

no I7Q

41.30

40.91

A K ff7

44.02

30.41

35.44 

32.73

39.57

46.27

37.48

46.69

33.83

Northern 

division

46.78

QQ 70

1Q Q7

A A AQ

48.46

44.35

41.68

33.95

34.63 

30.54

40.00

46.29

41.63

46.83

41.01

Southern 

division

48.68

QQ 7Q

65.95

42.84

46.00

46.39

44.31

86.03

37.73 

28.39

41.27

45.83

38.79

47.25

39.16

Normal

Jan _______________________

Peb _______________________

Mar ______________________

Apr _______________________

May -_______ __--__ _ 

June ___________________

July ______________________

Aug ______________________

Sept ______________________

Oct _______________________

Nov ______________________

Dec _______________________

Annual ____ _ _

3.10

2.69

3.84

3.21

3.62

3.60

4.18

4.77

3.60

2.84

3.16

2.87

3.47

2.92

4.10

3.91

4.07

4.01

4.65

4.91

4.06

3.42

3.88

3.56

3.45

2.99

4.09

3.45

3.78

3.62

4.37

6.06

3.79

3.35

3.74

3.26

41.28 48.96 44.95

George (1966, p. 37) described this province as producing the 

highest sediment yields in nonurban areas of the State. The general topography is rolling to hilly. Elevations range from 560 feet 

near Hopewell to 53 feet at Princeton. More than thr^e-fourths 

of the land slopes are classified between 0 and 6 percent grade 

(Stony Brook-Millstone River Watersheds Assoeiat'on, 1956, 

p. 3).

The basin is underlain (Bascom and others, 1909) by sedimentary members of the Newark Group that is, the Stockton Formation, Lockatong Formation, and Brunswick Shale and1 by intrusive diabase (fig. 2). The Stockton Formation, the oldest unit of 

the Newark Group in this area, is exposed over approximately 5 

percent of the basin. It is composed generally of varicolored sandstone, arkose, and scattered thin red shale. The Lockatong Formation, which underlies approximately 32 percent of the basin, is a 

hard dark argillite that includes some thin-bedded sandstone. The 

youngest formation of the Newark Group exposed is the Brunswick Shale, which underlies approximately 48 percent. It consists
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L7

of soft red shale that locally includes a few layers of sandstone. 

Diabase is exposed along the northeast edge of the upper part of 

the basin, along the northern divide between Hopewell and Princeton, and at two points north of Pennington. Because of its greater 

resistance to weathering, the diabase forms the highlands of much 

of the northern border. Approximately 15 percent is underpin by 

diabase.

Soils vary in physical character and in depth (U.S. So?l Conserv. Service, 1953). Those developed from the Stockton Formation are primarily sandy and silt loams ranging in thicknen from 

less than 24 inches to very deep; those from the Lockaton Formation are generally silty loams, ranging in thickness froir 20 to 

more than 36 inches; those from the Brunswick Shale are generally silty loams, ranging in thickness from less than 12 to 36 

inches; and those from diabase are silt loams ranging from thin 

to thick. Even though the soils are generally thin in the diabase 

highlands, when exposed they may yield rather large quantities 

of sediment. The red shale which underlies much of the basin is

::::::'P^INCETON

From U.S. Geological Survey (1967)

FIGURE 2. Generalized geologic map of the Stony Brook basin.
L8 SEDIMENTATION IN SMALL DRAINAGE BASINS

a potentially high sediment yielder where silty and a low yielder 

where sandy.

LAND USE

The land-use distribution above Princeton as well as in several 

subbasins, as reported by George (1963, p. 17-18), if given in 

table 2. The sample values for the gaged area were reported by 

George to compare favorably to those reported earlier IT Palmer 

and others (1957).

A comparison was made between the aerial photographs obtained in 1957 by the USSCS and those by the U.S. Geological 

Survey in 1969. Changes noted were field checked; a planimeter 

was used to determine acreage; and the land usage, as of 1970, 

was tabulated in table 2. The same land-use categories used by 

George are given in this report, with the following exception: 

Because grass, hay, and pasture have similar erosion characteristics, these categories were combined.

TABLE 2. Land use, in percentage of area, as measured in 1957 and 1970 in 

the Stony Brook basin and selected subbasins

Woodland

Stony Brook at Princeton

Woodsville Brook at Woodsville

Baldwin Creek at Pennington

Stony Brook near Hopewell

Honey Branch near Rosedale

Stony Brook at Glenmoore 

(17.6 sq mi) ____ _____ .

1957

32.2

20.0

25.6

71.4

21.0

40.9

1970

32.5 

21.6 

26.1 

72.6 

18.3 

42.1

Cropland

1957

18.3 

17.0 

22.6 

2.4 

22.0 

15.5

1970

15.4 

1.6 

16.7 

2.4 

19.6 

11.7

Grass, 

hay, and 

pasture

1957

25.1 

42.0 

7.6 

9.5 

41.1 

22.6

1970

22.6 

42.0 

7.6 

8.9 

33.6 

21.9

Idle

1957

10.7 

12.0 

6.0 

7.1 

8.9 

12.8

1970

11.2 

ft.2 

9.4 

6.6 

10.3 

14.0

Urban

1957

13.7 

8.9 

8.3 

9.5 

6.9 

8.1

1970

18.3 

13.5 

10.3 

9.6 

18.1 

10.1

Woodlands constitute 32 percent of the land area. T 3se lands 

are principally in the northern and western parts of the basin. 

There has been a negligible net change in these lands since 1957. 

However, some areas idle in 1957 are now (1970) wooded, whereas some wooded areas in 1957 are now in another land-use classification.

Much of the land is used for farming, about 43 percent in 1957 

and 38 percent in 1970. In 1957, poultry, dairy, and cattle farms 

were scattered throughout the basin, but primarily in tl ^ western 

part. These farms nearly disappeared by 1970 and were replaced 

by "cash-crop" farming; that is the growing of soy beans, small 

grains, and corn without sufficient crop rotation. This type of
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSFY L9

farming probably creates greater erosion problems than previous 

types (H. B. Slayback, U.S. Soil Conserv. Service, oral commun., 

1970).

Most of the 5-percent net decrease in farmland is reflected by a 

similar increase in urban areas. The 18-percent urban land use 

exists mainly in the southeast, in the Princeton area, anc1 in the 

northwest, near Hopewell (fig. 1), Increased urban usage is greatest in the eastern part of the basin. This can be attributed1 chiefly 

to the development of housing and research facilities in the 

Princeton area.

About 11 percent of the land is classified as idle (1970). The 

net change from 1957 in this use is an approximate 0.5 percent 

increase. Much of this idle land is in abandoned submarginal 

farms along the northwest divide or in vacant lands west of 

Princeton. Some of this land exists as an interim phase between 

the change from farmland to suburban-residential use.

In the northern headwaters area near Hopewell, land that was 

classified as idle in 1957 seems to have been farmed previously. 

In 1970 these areas were primarily woodland. This change is 

attributed to less suitable soil for farming.

Within the Honey Branch subbasin, nearly 3 percent of the 

woodland area was converted either to idle or urban classifications 

owing to construction of a retention reservoir and housing. Urbanization in this subbasin increased 11 percent, primarily in 

areas that previously (1957) had been classified under the grass, 

hay, and pasture category.

SEDIMENTATION

Stony Brook and Millstone River were impounded in 1907 to 

create Carnegie Lake (fig. 1) for use by Princeton University for 

recreation. Extending about 3.5 miles, the lake has an average 

width of over 500 feet. The upper Millstone River enters the lake 

about 2 miles above the dam. The lake's original storage capacity 

was 1,355 acre-feet (422 million gallons).

Sediment accumulation in the lake became a problem within a 

few years after impoundment. The University found it necessary 

in 1927 to dredge a channel from the boathouse in the upper end 

(Stony Brook) of the lake to deep water in the center. Tl^e upper 

1.5 miles of the lake was again extensively dredged between 1937 

and 1939. Permanent cross-section monuments were established 

in 1950 on each side of the lake at 2,000-foot intervals throughout 

its length. Results of a survey in 1950 (Moore and others, 1952) 

indicated a total deposition of 410 acre-feet of sediment, including
L10 SEDIMENTATION IN SMALL DRAINAGE BASINS

dredged materials, since the original impoundment. Results of a 

survey in 1959 (U.S. Soil Conserv. Service, 1959) indicated that 

the total sediment accumulation had increased to 459 acre-feet. 

Another survey in 1968 (Praeger and others, 1968) reported that 

651 acre-feet of material would have to be removed to restore the 

original hard bottom.

Moore and others (1952, p. 19) estimated that 1.3 percent of 

the total sediment accumulated in Carnegie Lake before 1950 was 

contributed by Millstone River and 98.7 percent by Stony Brook. 

Results of their investigations suggest that permeable soils, low 

stream gradients, and the presence of several dams in the upper 

Millstone River basin minimize the sediment contributed by this 

river system.

STONY BROOK AT PRINCETON

Because of its greater sediment contribution, Stony Brook was 

chosen by the cooperating agencies for intensive investigation. 

Daily measurements of suspended-sediment discharge of Stony 

Brook were begun in January 1956 in order to define the sources 

of suspended-sediment discharge from the basin and to evaluate 

any trend in sediment discharge over an extended period. Between January 1956 and June 1970, more than 127,000 tons of 

suspended sediment was transported from the basin at an average annual discharge of 200 tons per sq mi.

Streamflow- and sediment-duration curves (fig. 3) were prepared to evaluate the distribution of daily data with respect to 

time. Note that high streamflow, suspended-sediment concentration, and sediment discharge represent only a small percentage of 

the total time period. For example, although days vlien more 

than 100 tons of sediment was transported occurred only 2.5 percent of the time during the 1956-70 period, these days accounted 

for 88 percent of the sediment load. Conversely, though days of 

low suspended-sediment discharge are frequent, the totel sediment 

discharge during these times of minimum streamflow is small.

Another application of duration curves is in the determination 

of the percentage of time that a particular parameter equaled or 

exceeded or, conversely, was less than an indicated value. For 

example, the median streamflow, that equaled or exceeded 50 percent of the time, is 18.5 cfs (cubic feet per second) ; median 

suspended-sediment concentration is 5.6 mg/1 (milligrams per 

liter) ; and median suspended-sediment discharge is 0.24 ton per 

day. Similarly, values for other frequencies of occurrence can be 

described.
WATER DISCHARGE, IN CUBIC F

SUSPENDED-SEDIMENT CONCENTRATION

SUSPENDED-SEDIMENT DISCHARGE
L12 SEDIMENTATION IN SMALL DRAINAGE BASINS

The seasonal and annual variations of the suspended-sediment 

load transported from the basin are shown in table 3. Generally, 

low sediment loads are concurrent with low streamflows from 

August to October, with higher loads in the remaining months. 

Although moving averages tend to dampen extremes of shortterm fluctuations in the chronologic sequence of the parameter 

analyzed, the plot illustrated in figure 4 shows that the decreased 

quantity and intensity of storms and resultant low streamflows 

during the 1962-66 drought resulted in sediment discharges being 

reduced considerably. One of the few beneficial environmental 

effects of drought is the reduction of the amount of soil erosion 

and stream sedimentation undoubtedly related to the reduction 

in the number and intensity of storms. Based on the anrual loads 

at Princeton (table 3), sediment discharges were reduced nearly 

tenfold between 1961 and 1965.

MULTIPLE-REGRESSION ANALYSIS

For most streams, there is a close relation between the rate of 

sediment discharge and that of storm runoff (Colby, 1956). If the

100

o

O 90 

O ill 

V)

m 80

Ill 

111 U. 70

U

m 

D 

" 60

5°

< 30 

5

20

3200

2800 !£

O

H

24OO -

ill" 

U

OC

2000 £

U

w 

o

16OO H

z

1200

800

4OO

1955 1960 1965 1970

FIGURE 4. Trend analysis, as shown by 12-month moving averages, of streamflow and 

sediment discharge, Stony Brook at Princeton.
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L13

TABLE 3. Suspended-sediment discharges, in tons, Stony Brook at Princeton,

1956-70

Year Jan. Feb. Mar. Apr. May June July

1956 _______

1957 __ _ __

1958 _ ____

1959 _______

I960 ______

1961 ___ _

1962 __ _ __

1963 ______

1964 _ __ ___

1965 _______

1966 ___ _

1967 __ __ _

1968 _______

1969 _______

1970 __ ___

141

4.230

777

489

941

2,078

178

5,400

56

14

350

244

715

23

1,985

303

7,512

695

2,470

2,592

2,295

77

107

1,200

1,280

208

85

44

2,360

3,019

149

978

4,051

57

4,090

5,829

7,245

171

290

978

5,314

2,344

230

120

591

2,399

4,954

240

1,578

1,350

1,652

108

824

51

50

40

113

202

3,347

551

3.5

233

8.5

19

161

74

111

16

6.1

393

542

2,060

101

23

65.6

2.1

3.1

194

16

6.3

80

25

6.6

1.7

4.9

184

682

11

181

5.6

.2

2,239

7.5

1,666

1,426

33

18

248

2.7

.8

434

2.3

3,653

Year Aug. Sept. Oct. Nov. Dec. Annual

1956 ___________

1957 __ _ _________

1958 _ __ __ ___

1959 _ __ ___ __

I960 _______ ___

1961 _____ __ _

1962 - _____ 

1963 _ ___

1964 _ ___ __ __

1965 _ __ _ ______

1966 _ _____ __ __

1987 _ __ ____

1968 _ _ __

1969 ___ _ __ _

1970

1 9

.5

26

192

17

200

125

17

1.7

1.9

.2

858

2.2

168

2.0

2.2

5.7

40

2,647

136

28

259

4.8

11

214

5.1

1.5

1,155

0.7

.9

359

2.2

56

3.0

86

.5

5.1

2.1

884

274

21

190

127

7.4

701

91

130

23

1,460

211

1.7

.3

85

21

47

19

345

2,776

679

1,024

248

193

549

71

138

1.4

146

1,227

107

2,214

5,785

21,920

7,322

9,393

11,121

14,299

8,319

6,923

1,625

4,050

9,457

5,709

8,701

availability or transportability of these sediments changes, the 

relation of sediment to water discharge also may change. / s each 

storm is unique, each having different meteorologic, hydrologic, 

and areal cover patterns, the data can be assembled, logically, on 

a single storm basis. An analysis of data from a large number of 

storms is simplified by use of a digital computer, as many variables would be necessary to define the transport of sediment.

The most comprehensive method for analysis of data is through 

a multiple-regression analysis. Such an analysis was made on the 

Princeton data to obtain the best fit of several variables (independent) that affect the transport of suspended sediment (dependent variable) for given storms. A multiple regressior of the 

following mathematical form was used:

Y^bo+bi Xt+b2 X2+ .. .bn Xn

where constants b Q to bn are the partial-regression coefficients; Y, 

the estimated dependent variable; and X: to Xn, the independent 

variables.

The following regression models, which are basically those discussed by Guy (1964), were used to define predictive equations:
L14 SEDIMENTATION IN SMALL DRAINAGE BASINS

log S£=&0+&ilog Qt (1) 

logS^&o+WogQw (2) 

log C=&0+&1 logQ, (3) 

log C=&0+&ilogQ«, (4) 

log C=&0+&xlogPn (5) 

log C=&0+&ilogQ«,+&2logPn (6) 

log C^bo+bjog Qw+b2log Pw+&3log Qa (7) 

log C=&0+&ilogQw+&2 logPn+&3logQ0+&4logQ6 (8) 

log C=&0+&ilog Qw+b2log Pn+&3 log Qa+bjog Q6+M* (9) 

log C=&0+&ilog Qw+62log Pn+&3log Qa+&*log Q6+M*

+&6rm (10) 

where Si is the suspended-sediment load for a storm, in tons ; C, 

the mean sediment concentration for a storm, in mill' grams per 

liter; Qt, the surface runoff due to the storm, in cfs-days (cubic 

feet per second-days) ; Qw, the net water discharge due to the 

storm, in cfs-days; P», the peak rate of water discharge minus 

the base flow, in cubic feet per second; Qa, the 'antecedent streamflow at the beginning of the storm, in cubic feet per second ; Q&, 

the base flow during the storm, in cfs-days ; At, the normal daily 

air temperature during the storm, in degrees Fahrenheit ; and Tm> 

the accumulative time since the first storm, in tenths cf a month.

Many hydrologic and climatologic variables affect the sediment 

transported from a basin. Using a multiple-regression analysis, 

one can evaluate from the correlation coefficients the nost useful 

variables for determination of the optimum mathematical expression. The search for useful variables is reported to b<5 limitless 

(Guy, 1964, p. 22). However, many of these variables f.re of little 

use as an independent variable. This is due to either low correlalation, poor quality of the data, or high intercorrelation with 

other variables. In addition, significance of a variable as an independent quantity is reported to vary from basin to basin (Guy, 

1964, p. 42-46).

Some variables were not used because data are either not available or are inaccessible in usable form. For example, precipitation 

intensity in the study area is difficult to evaluate and often is too 

inaccurately determined for an effective measure of storm intensity. Thus, the peak-flow rate of the storm-streamflow hydrograph 

(fig. 5) was used as a partial measure of precipitation intensity. 

High intercorrelation was found between peak-flow rates and 

other hydrologic variables. This is due to the antecedent streamflow (Qa ) and the base flow (Q6 ) being included in the value of 

the total peak streamflow (Pt). The intercorrelation w^s reduced 

by subtracting the estimated base flow from total streamflow at
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L15

3.0

t Pt: 5.88-ft gage height = 1530 cfs

Base flow 

20 cfs 

66 cfs

Qt = 546 cfs-days Qb = 86 cfs-days

Pn =i 1530 cfs - 36 cfs = 1490 cfs ~~

Storm peak base flow: 

2.08-ft gage height = 36 cfs

Qg : 2.10-ft gage height = 38 cfs 

I , , , t

Dec. 6, 1962 Dec. 7, 1962 Dec. 8, 1962 

FIGURE 5. Representative storm hydrograph, Stony Brook at Princeton.

the time of each peak. Consequently, the net peak-storm streamflow (Pn ) was used to partly represent the storm intensity.

Base flow was determined from hydrographs (fig. 5) in a manner similar to that described in Davis and DeWiest (1967, p. 30- 

32). This technique involved extending the dry-weather recession 

curve (that is, the flow recession curve preceding the storir to the 

time of the peak flow A to B in fig. 5). From this point of intersection (B), a line is drawn at an angle of 30° to its intersection 

(C) with the storm's recession curve. Base flow was subtracted 

from the streamflow to obtain the direct runoff from each storm. 

Likewise, the net storm peak was derived by subtracting the base 

flow at point B from the streamflow peak.
L16 SEDIMENTATION IN SMALL DRAINAGE BASINS

A measure of the seasonal variation of sediment vras needed. 

Assignment of arbitrary numbers to months of the year was 

found to be indefinite. As seasonal variation reflects climatic variation, some measure of this variation could logically be used. 

Daily normal air temperatures ( U.S. Weather Bureau, 1963) 

were chosen, as their partial-regression coefficients agreed well 

with those of the mean daily air temperatures during storms. Soil 

temperatures also were tried, but air temperature? produced 

higher correlation coefficients than soil-temperature data.

Storms with sediment loads of less than 1 ton per dry were not 

considered for the regression analysis. Also, storms in which 

streamflow hydrographs had nearly equal double peaks were not 

used. Between January 1956 and June 1970, there were 354 major 

storms that met these criteria, during which 90 percent of the 

total sediment load was transported.

Standard error of estimate was used in selecting the mathematical model best fitting the data. The smaller the value of the 

standard error of estimate, the better the model describes the 

suspended-sediment discharge from the basin. The standard errors 

of estimate for the 10 regression models (p. L14) are: 0.412, 

0.377, 0.337, 0.320, 0.292, 0.293, 0.291, 0.271, 0.268, and 0.260 log 

units, respectively. It is evident that as additional variables are 

added to the model an improvement is made in its ability to describe the dependent variable. Model 5 produced a relatively low 

standard error of estimate (0.294 log units), with the least number of variables. Little improvement was made by the addition of 

antecedent flow, base flow, temperature, or time trend in the regression analyses.

The net peak discharge was found to be the most significant 

independent variable, and the magnitude of the time trend the 

least significant for describing sediment variations. The partialregression coefficient, a measure of the interdependent variable 

correlation with the dependent variable, for the time of the storm 

was found to be negative; that is, the sediment concentration decreases with increasing time of the storm. This can be interpreted 

as indicating a long-term reduction in storm-sediment concentration. The daily normal air temperature, a measure of seasonal 

effects, also varied inversely with sediment concentration. The 

high degree of negative intercorrelation between air temperature 

and seasonal storm periods unquestionably produced the relation 

that is observed here.

The regression constants for each of the 10 models using the 

1956-70 storm data are listed in the following table.
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L17

Model

1 __________

2

3 _ _

4

5 __ _ _

6 _

7 __________

8 __________

9 __ _ _____

10 ______

bo

_ _ _ 2.0837

_______ 1.5349

 .6491

__ ____ .7293

_______ .4768

._ ____ __ .4580

.4880

_ ____ _ .5948

_ ______ .8521

. _______ .8854

b,

1.5633

1.4343

.4353

.4309

.4836

 .1508

 .1146

.1014

.0

.0

62

0.6253

.6195

.5765

.6627

.6362

bs

 0.0737

.2908

.2523

.1995

bt bs

 0.5481

 .5560 0.0036

 .4567 .0027

be

 0.0014

These constants can be used to predict the suspended-sediment 

concentration, given knowledge of the other parameters.

Model 2 is a regression of the two variables used for a unit rate 

of sediment-transport curve. A plot of this regression is illustrated in figure 6. It does not seem that the observed sediment 

data for any of the years of record plots above or below the line 

of regression. Therefore, a trend cannot be detected in tl is illus10,000

EXPLANATION 

« 1956-57 

» 1958-59

* 1960-61 

v 1962-65

 1966-70

100

1.0

10 1OO 1OOO 

NET WATER DISCHARGE, IN CFS-DAYS PER STORM

10,000

FIGURE 6. Suspended-sediment transport curve based on storm runoff, Ston^' Brook at

Prince ton.
L18 SEDIMENTATION IN SMALL DRAINAGE BASINS

tration. Consequently, another method of analysis must be considered. Note also that in areas above 1,000 cfs-days this linearregression analysis seems to be an inaccurate predictive model. 

Sediment-load values predicted are generally lower than those observed. A nonlinear expression would probably be of greater use 

for prediction.

DOUBLE-MASS-CURVE ANALYSIS

Another technique, that involving a double-mass curvs, also 

has been used (Guy, 1957) for studying trends in sediment yield 

and in detecting the effect of watershed practices on sediment 

yield. A double-mass curve (Searcy and Hardison, 1960) is a plot 

of the cumulative observed data for one variable against the 

cumulative observed or calculated data for another variable. The 

plot will be a straight line when variations in both parameters are 

proportional; the slope of the line will represent the constant of 

proportionality between the quantities. Each break in slope represents a point in time at which a change has occurred in the 

relation between the two quantities analyzed.

A double-mass curve of net storm runoff and suspended-sediment discharge at Princeton is illustrated in figure 7. The parameters plotted are those used in model 2. Several breaks in slope 

can be seen. For example, the slope changed in late 1957. This is 

in agreement with an earlier observation by George (1963, p. 69), 

who concluded that urban expansion and reservoir construction 

produced temporarily high average sediment yields from 1957 to 

1959. Large breaks in the curve, such as those in 1959, 1962, 1964, 

1967, and 1970, are difficult to explain. Similar patterns (H. P. 

Guy, written commun., 1972) have been observed or other 

streams and seem to occur at the time of rather drastic (nonseasonal) weather changes, especially rather large storms. The 

breaks illustrated seem to concur with the first major storm subsequent to the spring thaw.

Interpretation of the data on this curve is complicated further 

by at least two factors: (1) the construction of several sediment 

retention reservoirs during 1958-70 and (2) an extreme drought 

during 1962-66.

If the drought is ignored and if the slope during the early 

years, 1956-61, is compared with that subsequent to the drought, 

1967-70, then the following observations can be made. From 1956 

to 1961, the slope of the curve is 1.03; from 1967 to 1970, it is 

0.80. This suggests an overall change in the relation of about 22 

percent. However, four of seven retention reservoirs were com-
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L19

pleted in the early period and only one during the later period. 

The change in slope may reflect the reduction in temporarily high 

sediment yields due to reservoir construction.

Figure 7 indicates that the proportionality between vater and 

sediment discharges changes with time. However, which of the 

two parameters caused the variation in the proportiorality? In 

order to answer this question a double-mass-curve analyses of 

observed data against values derived from model 10 was made and 

illustrated in figure 8. Model 10 was chosen, as it is the most accurate in predicting sediment transport. Also, variation* in sediment concentration, rather than load that includes both streamflow and sediment, can be considered. In effect, this illustration 

indicates periods in which the observed concentrations are higher 

or lower than the average, as derived by regression analysis, for 

the entire period of record.

Note the six periods of relatively consistent slopes dur'ng 1956- 

58, 1959, 1960-62, 1963-66, 1967, and 1968-70. These periods of 

consistent slope are almost concurrent with similar periods in

no h 197tK

 \

100

o

OC 90

*u. 70 

lo

ogso

w h

>Z 40

I- 

< 

^ 30

1

" 20

10

0 10 20 30 4O SO 60 70 80 90 1OO 110 12O 130

CUMULATIVE NET STORM RUNOFF, IN THOUSANDS OF CFr DAYS

FIGURE 7. Double-mass relation of net storm runoff and storm suspended-sednrent discharge,

Stony Brook at Princeton.
L20 SEDIMENTATION IN SMALL DRAINAGE BASINS

figure 7. Consequently, it is concluded that changes in proportionality are related, at least, to variations in sediment concentrations and not entirely to variations in water yield. Also, note that 

observed sediment concentrations were higher than average during 1958-59,1962-66, and 1968-70 and that they were lower than 

average during 1960-61 and 1967. The periods of higher than 

average sediment concentration is coincident with retention reservoir construction in the basin. For example, three reservoirs 

(table 5) were completed between 1959 and 1960, three were completed between 1962 and 1964, and one in 1969. The higher yields

30

25

O £ 

§320

h- UJ Z o.

Il

0 <

Q - 

Z 5

i<

.0

2"

c z

.S

A

5 10 15 20 

CALCULATED STORM SUSPENDED-SEDIMENT CONCENTRATION, 

IN THOUSANDS OF MILLIGRAMS PER LITER

25

FIGURE 8. Double-mass-curve relation of observed and calculated storm-sedirrent concentrations, Stony Brook at Princeton.
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L21

observed during 1958-59, 1962-66, and 1968-70 may be explained 

partly by earth moving in and near the stream channel from the 

construction of these reservoirs.

SUBBASIN-SEDIMENT YIELD

Five sediment-sampling locations were established within the 

basin at which sediment-load data were collected during stormrunoff. The period of record is listed in table 4. Measurements 

were made in order to identify areas yielding abnormally high or 

low quantities of sediment. The location of these sites an'! the 

drainage area above each location is shown in figure 9.

Storm data collected at these intermittent sampling site^ are 

summarized and compared graphically (fig. 10) with similar data 

collected at Princeton. These plots show that the average sediment load per square mile transported by the Stony Brook near 

Hopewell, Honey Branch, and Stony Brook at Glenmore are less 

than that carried at Princeton. The loads from Baldwin Creek 

generally exceed those at Princeton below 7 tons per sq mi and 

are less that those at Princeton above 7 tons per sq mi. Woodsville 

Brook is transporting a greater load per square mile than Stony

EXPLANATION

A, Woodsville Brook at Woodsville

B, Baldwin Creek at Pennington

BL, Baldwin Lake near Pennington

C, Sffiny Brook Tributary No. 3 near Hotewell

D, Honey Branch near Rosedale

E, Stony Brook at Glenmoore

P, Stony Brook at Princeton

PRINC7TON

 ' " Drainage divide 

 Sampling site drainage divide 

V Sediment-sampling site 

Streamflow-gaging station 

Reservoir (not to scale) with U.S. Soil 

Conservation Service site number

FIGURE 9. Map showing location of subbasin sediment-sampling stations and sedimentretention reservoirs.
L22 SEDIMENTATION IN SMALL DRAINAGE BASII T S

Brook at Princeton. However, data collected to date at this latter 

sampling site define the relation in only a small region of the 

graph and, thus, may be insufficient, for valid interpretation.

100

< 10

a:

> ui

M O1.0

0.1

10OO

EIOO

U| OC 

UI <

0:3

10

z

O 

KT.O

0.1 1.0 10 10O 2

STONY BROOK, 

IN TONS PER SQUARE MILE

1OO

^< 5

10

* w i.o

On 

O ui 

C

m,

;i-o.i

0.01

0.1

6.1 1.0 10 100

STONY BROOK, 

IN TONS PER SQUARE MILE

1OO

0.1 1.0 10 1OO 

STONY BROOK, 

IN TONS PER SQUARE MILE

10

STONY BROOK. 

IN TONS PER SQUARE MILE

100

1OO

1.0 10 1OO 

STONY BROOK, 

IN TONS PER SQUARE MILE

FIGURE 10. Sediment-load relation between subbasin sampling stati

Prineeton.

ions and ftony Brook at
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSE^ L23

Using graphs similar to those in figure 10, George (196"*) determined the percentage of load yielded by each subbasin to the 

amount at Princeton (table 4). Storm-load samples collected after 

George's study plot in a manner similar to those he reported. Consequently, no change in this correlation was considered. Total 

suspended-sediment load at Princeton during January 1956 to 

June 1970 was about 127,000 tons, or 8,800 tons per year. Applying the percentage values listed to the average annual suspendedsediment discharge at Princeton results in a computed annualsediment discharge for each subbasin. These results, which are 

summarized in table 4, range from roughly 25 to 400 tons per sq 

mi and compare well with the earlier estimates of Anderson and 

George (1966, p. 38) for this physiographic province.

Note that the highest yield, 405 tons per sq mi, was observed 

on Baldwin Creek (fig. 9, site B). This basin mainly drains the 

Brunswick Formation (fig. 2). Conversely, the lowest yield, 28.4 

tons per sq mi, was observed on Stony Brook tributary No. 3, 

which principally drains diabase rock. Other subbasin sampling 

sites also were chosen to be representative of underlying geologic 

formations. For example, Honey Branch mainly drains the Brunswick Formation, Woodsville Brook the Lockatong Formation, and 

the Stony Brook at Glenmore a composite of the Stocktcn and 

Lockatong Formations and diabase rocks.

TABLE 4. Computed average annual suspended-sediment discharge of Stony

Brook subbasins

Period Percentage 

Subbasin of of Princeton 

record load

Stony Brook at Glenmoore 

(17.6 sq mi) _ ____ _ _ 1956-59, 1970 ______

Honey Branch near Rosedale 

(4.02 sq mi) _ ____________ 1956-59, 1969 _ __

Stony Brook Tributary 

No. 3 near Hopewell 

(2.57 sq mi) _________ 1956-57, 1970 ____

Baldwin Creek at Pennington 

(1.92 sq mi) __ ___ __ 1956-59, 1968 ______

Woodsville Brook at Woodsville 

(1.86 sq mi) _ _ __ __1956-58, 1970 - -

28.7 

5.4

.7 

7.5 

4.9

Suspended-sediment discharge

Tons

2,990 

560

73 

779 

509

Tons per sq mi

169 

139

28 

405 

273

SEDIMENT-RETENTION RESERVOIRS

Seven small reservoirs were constructed in the basin by the 

USSCS between 1958 and 1969. Each reservoir was designed to 

retain a large amount of the transported sediments normally carried downstream. The location of these sites is shown in figure 9.
L24 SEDIMENTATION IN SMALL DRAINAGE BASINS

A listing of the storage, drainage area, and approximate completion date is given in table 5. The drainage area above these reservoirs is 14.2 sq mi, or roughly 25 percent of the basir's drainage 

area. The USSCS estimated that these reservoirs would reduce 

the amount of sediment transported from the entire basin by 61 

percent (M. P. Crooks, written commun., 1960).

TABLE 5. Descriptive data on retention reservoir?

Site 

(fig. 9)

2 _____

4 _____

7 _____

11A_ _

5 ____

14 ____

3 _ __

Reservoir name

Storage 

(acre-ft)

16

107

43

47

77

125

69

Drainage 

area 

(acres)

256

1,088

422

595

1,609

2,260

932

Percent of 

basin drainage area

0.89

3.82

1.48

2.09

5.69

7.94

3.27

Completion 

date

Aug. 1959

Sept. 1960

Jan. 1962

Jan. 1984

Dec. 1964

Oct. 1969

One of these P.L. 566 retention reservoirs, Baldwir Lake, was 

selected for a sediment-trap efficiency investigation. This lake 

(site 5, fig. 9), built in 1960 and modified slightly in 1962, is 

about 1 mile north of Pennington. Daily records of suspendedsediment discharge were collected at the lake overflow outlet 

(drainage area 2.52 sq mi) between October 1962 and July 1969. 

Monthly and annual sediment loads at this station are summarized 

in table 6. In addition, storm-sediment data were collected at a 

point upstream from the lake, drainage area of 1.92 si mi.

As part of the trap-efficiency study, topographic surveys of the 

lake bottom were completed in 1960 and 1964. Because the lake 

was drained and modified in 1962, comparison of these surveys 

cannot be used to define the lake's trap efficiency accurately. The 

USSCS currently (1972) plans similar surveys periodically, at 

least every 5 years. Upon completion of additional surveys, it will 

be possible to determine the volume of sediment deposited in the 

reservoir. However, it is possible to estimate the lake's trap efficiency by the techniques described in the next paragraph.

Computations, based on 1962-69 records, indicate a sediment 

discharge from Baldwin Lake of about 117 tons per year, or an 

annual sediment yield downstream of approximately 46 tons per 

sq mi. When compared to the average annual yield of Baldwin 

Creek before reservoir construction (about 433 tons per sq mi), 

a reservoir-trap efficiency of 89 percent is indicated. P. ssuming all 

P.L. 566 reservoirs are equally efficient, the result should be a 

reduction in sediment yield into Carnegie Lake of about 20 percent. However, a greater percentage reduction would be expected,
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L25

TABLE 6. Suspended-sediment discharges, in tons, Baldwin Creek at Baldwin

Lake, near Pennington

Year Jan. Feb. Mar. Apr. May June July

1962 __ __.

1963 ___ .

L964 _ __ .

1965 __ .

L966 __ .

1967 -__ .

L968 ___ .

1969 __ .

6.1

31.7

o 7

.8

. ____ 21.1

6.4

. ____ 8.4

17.7

5.6

13.8

50.7

7.7

9 7

1.8

34.2

5.9

14.3

20.4

91.8

58.4

47.0

1.0

12.8

0 Q

.5

2.0

2.1

4.0

n o

1.4

.2

3.5

7.7

50.9

1.2

.1

.0

.0

.3

1.0

27.2

.4

0.0

1.1

.0

.0

15.7

.1

32.2

5Tear Aug. Sept. Oct. Nov. Dec. Annual

1962 ____ _.

1963 _ _ _ _.

1984 _ _ __ .

1965 ______

1966 __ _ __ .

1967 _ _ __ .

L968 __ __ .

0.0

.0

.7

.0

16.4

.0

0.0

.0

.5

3.3

.9

.0

0.0

.0

.3

.2

40.2

1.5

.0

9.5

11.6

.5

.1

1.8

1.3

1.3

8.4

2.6

15.2

.2

4.3

71.6

4.5

73.6

74.5

35.5

125.8

238.7

153.6

as these reservoirs are in areas of potentially high sediment yields. 

These computations assume that the period of sediment-discharge 

records from Baldwin Lake are representative of the average, 

that the average annual yield from the basin before construction 

has not significantly changed, and that all reservoirs are equally 

efficient. Also, the average-annual yield for the Baldwin Creek 

basin before reservoir construction was developed on the basis of 

comparatively few storm data. The 89 percent reduction value 

may be high in that the period of sediment-discharge records 

(1962-69) on Baldwin Lake includes 5 years of extreme draught 

(1962-66), with resultant lower than normal sediment discharges. 

As these reservoirs fill with sediment their efficiency can be 

expected to decrease. Also, because a stream has a certain inherent capacity to carry sediments, some material from the channel 

and banks will be picked up by the stream below these reservoirs, 

reducing the reported efficiency of the reservoirs. In addition, as 

additional areas of the basin are urbanized, an increase in impervious areas will result in increased runoff and cause channel 

enlargement. This will probably result in increased sediment 

transport below the P.L. 566 reservoirs.

SEDIMENT-PARTICLE SIZE

Analyses were made on several occasions to determine the 

particle-size distribution of suspended sediments in Stony Brook. 

Samples were collected during periods when direct runoff constituted most of the flow and when suspended-sediment concentrations were relatively high. As most of the sediment is transported 

during storms, these samples closely represent the size distribu-
L26 SEDIMENTATION IN SMALL DRAINAGE BASINS

tion of a large percentage of the suspended sediment transported 

annually.

Samples of suspended sediment collected at Princeton and 

analyzed for particle-size distribution were compared by relating 

each size distribtuion to its corresponding water discharge and 

then grouping the discharge into three ranges by using the 

streamflow duration curve in figure 4: those discharges expected 

to be equaled or exceeded 0.1 percent of the time or less; those 

expected between 0.1 and 1.0 percent of the time; and those expected between 1.0 and 10 percent of the time. The average 

particle-size distributions for these three streamflow duration 

ranges are illustrated in figure 11. The American Geophysical 

Union's classification of particle size is used in this illustration 

(Lane and others, 1947).

Comparison of the curves in this illustration indicate some interesting variations in particle size with changing flow frequency. 

Amounts of material in each class of samples collected during 

flow duration of less than 0.1 percent and 0.1-1.0 percent are 

approximately identical; roughly 40 percent clay, greater than 55 

percent silt, and minor amounts of sand. Distributions at durations of 1.0-10 percent have higher clay sizes (50 percent) and 

lower silt sizes (45 percent). Clay and silt predominate in all 

samples and make up 96-99 percent of this suspenc^d-material 

transported. Transport of sand sizes increases somewHt at lower 

duration, that is, at higher flows.

99.9

99.0

98

50

10

5

2

1.0

0.001

SIZE DISTRIBUTION AT INDICATED 

STREAMFLOW DURATION 

Less than or equal to 0.1 percent of time

 Greater than 0-1 but ler$ than or equal to 

1 percent of time

 Greater than 1 but less than or equal to 

10 percent of time

-Clay- -Silt -Sandl i i i i i i

0.01 0.1 

DIAMETER, IN MILLIMETERS

1.0

FIGURE 11. Average particle-size distribution of suspended sediment, Stony Brook at Princeton.
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L27

In addition, samples of lakebed material were collected in April 

1959 at several points for subsequent particle-size analysis. The 

purpose of this sampling was to determine downstream variation 

in particle-size composition of the lake-deposited sediments. Results of these analyses are shown in table 7. The first two distributions listed in the table represent sediments composited from 

bed samples collected in Carnegie Lake above confluence with the 

Millstone River. The second pair of distributions represent lakebed samples collected below the river confluence. There is little 

difference between particle-size distributions for the two pg.irs of 

samples.

TABLE 7. Particle-size distribution of sediments deposited in Carnegie Lake

at Princeton

Percentage of

Clay

0.002

. _ 16

15 

______ 11

10

0.004

26 

29

24 

23

sample finer than indicated size (mm)

Silt

0.008

48 

47 

45 

37

0.016

63 

65 

62

54

0.032

88 

80 

81 

67

Sand

0.062

97 

90 

97

87

0.125

99 

92 

99 

90

Praeger, Kavanagh, and Waterbury (1968) reported analyses 

of material collected in January 1968 from the "upper" and 

"lower" layers of Carnegie Lake. The percentage of material in 

each soil class is:

Clay Silt Sand

Upper layer _ 25 70 5 

Lower layer _______ 22 72 6

These compare closely to those collected in April 1959 (tables 7).

Average particle-size composition of suspended-sediment samples collected from Stony Brook at Princeton indicates 3 percent 

sand, 53 percent silt, and 44 percent clay. The average composition of sediments deposited in Carnegie Lake (table 7) was found 

to be 7 percent sand, 68 percent silt, and 25 percent clay. These 

data show slightly higher percentages of sand (which may lv» due 

to high sand content in sediments transported by the Millstone 

River, which drains Coastal Plain sediments) and somewhat 

smaller percentages of clay in the deposited sediments. Some of 

the very fine sediments transported into the reservoir are probably 

not deposited, but are carried over the dam. In part, this exolains 

the differences between the composition of the suspended and deposited sediments.
L28 SEDIMENTATION IN SMALL DRAINAGE BASINS 

CHEMICAL QUALITY

In general, streams draining the basin are similar in chemical 

characteristics. The alkaline earths, calcium and magnesium, are 

the predominant cations, making up 70-90 percent of the total. 

Calcium-magnesium hardness usually ranges in pH from 6.7-8.1. 

The waters are neutral to alkaline, ranging in pH from 6.7-8.1. 

Anions associated with strong acids, sulfate, chloride, fluoride, 

and nitrate, predominate, making up. 50-70 percent of the total. 

Of these, sulfate is found in larger amounts. This may be attributed to weathering of gypsum and red shale. Alkalinity, almost 

always bicarbonate, makes up the remaining 30-50 percent of 

the total anions. Dissolved solids generally range from 100 to 

250 mg/1.

Results of six spectrographic analyses of water samples collected at Princeton for trace elements were recently reported by 

Anderson (1970). A summary of the maximum and minimum 

value observed in these samples for several elements is listed 

below. In addition to those listed, the following elements were

Element Range

Aluminum _ ___ _ ________ _ __ ______ 15 -900

Barium _________ ________ __ ___ _ 25 - 70

Boron _____ ___ ___ _________ __ ______ __ 29 - 90

Chromium _ ___ _ ___ ___ ___ ____ .3- 4.0

Copper. ______ __ _________ __ __ ___ 2.0- 28

Lead ____________________________________ .7- 7.0

Lithium _ ___ ___ __________ ___ ___ _ .4- 5.0

Molybdenum _ __ __ ___ _ __ _______ _______ .0- 3.0

Nickel __________________________________ _ 3.0- 7.0

Rubidium _________ __ _______ __ ____________ __ 1.0- 7.0

Strontium ______________________ _ __________ 60 -320

Titanium __________________________________ 1.0- 19

Vanadium ____ __ ______ _ _ __ ___ ____________ ___ .0- 6.0

sought, but were not observed in analyzable quantities : beryllium, 

bismuth, cadmium, cobalt, gallium, germanium, silver, tin, zinc, 

and zirconium. In general, iron concentrations were less than 500 

fj.g/1 (micrograms per liter) and manganese less than 150 /*g/l. 

Comparison of these analytical results with others in the State 

produced no anomalies.

In addition to chemical and spectrographic analyses of water 

samples, special samples were collected in the fall of 1967 and 

the spring of 1968. Water and bed-material samples were collected at the gaging station and at three points in Carnegie Lake. 

The samples were analyzed for 10 chlorinated hydrocarbon pesti-
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L29

cides, and the results are summarized in table 8. The data iHicate 

the presence of several chlorinated hydrocarbon insecticides.

TABLE 8. Pesticide analyses of water and bed samples collected frotn Stony 

Brook and Carnegie Lake at Princeton, 1967-68

Tlfl,

1 0 

§

H

§ 1

(3

1

3 o

a

I

£

 C

1 ffi

0)

a 

J

WATER SAMPLES

[Results in micrograms per liter]

01-4010.00 Stony Brook at Princeton, N.J.

09-15-67 

05-20-68

09-15-67 

05-20-68

_____ 0.00 

__ _ .00

Carnegie

0.00

 .00

0.00 

.01

Lake at

0.02 

.04

Carnegie Lake at Princeton,

09-15-67 

05-20-68

09-15-67 

05-20-68

_____ 0.00

Carnegie Lake

0.00

_____ .00

0.01 

.03

0.00 

.01

0.00 

.03

Princeton, N.J.

0.00 

.08

N.J.

0.00 

.05

0.02 

.25

0.00 

.01

0.00 

.00

o.oc 

.or

0.00 

.01

(boathouse)

0.01 

.00

(below Millstone

0.00 

.01

at Princeton, N.J. (0.25

0.01 

.01

0.00 

.02

0.01 

.01

0.03 

.20

mile

0.03 

.10

0.00 

.00

River

0.00 

.00

above

0.00 

.00

o.oc 

.oc

confluence)

0.00 

.00

dam)

0.00 

.00

0.00 

.00

0.00 

.00

0.00 

.01

BED SAMPLES

[Results in micrograms per kilogram] 

01-4010.00 Stony Brook at Princeton, N.J.

09-15-67 

05-20-68 _____ 0.00 

.00

5.0 

2.0

Carnegie Lake at

09-15-67 

05-20-68 0.00 

_ __ .00

Carnegie Lake at

09-15-67 

05-20-68

___ ___ 0.00

 .00

115 

200

Princeton,

110 

45

2.0 

.5

20 

5.0

Princeton, N.J.

3.0 

15

N.J.

2.0 

6.0

45 

75

0.00 

.00

0.00 

.00

0.01 

.01

0.00 

.00

(boathouse)

0.00 

.00

(below Millstone

25

11

Carnegie Lake at Princeton, N.J. (0.25

09-15-67 

05-20-68 0.00 

__ ____ .00

55

40

3.0 

4.0

15 

8.0

0.00 

.00

mile

0.00 

.00

0.00 

.00

River

0.00 

.00

above

0.00 

.00

0.00 

.00

confluence)

o.co

.CO

dam)

0.00 

.CO

0.00 

.00

0.00 

.00

0.00 

.00

The water-phase data indicate the presence of the DDT and its 

metabolites, DDD and DDE and some dieldrin and lindane. Concentrations seem to be slightly higher in samples collected in the 

spring than those in the fall, perhaps indicating an inpnt from 

agricultural usage.

The bed-material data indicate only the presence of the DDT 

family. Data collected during the spring show concentrations at
L30 SEDIMENTATION IN SMALL DRAINAGE BASINS

one site (boathouse) increasing in the amount of DDT-type compounds in relation to fall samples, while decreasing at the other 

three sites. The reason for this is unclear, but may be related to 

sampling techniques or bed movement. Values in the Carnegie 

Lake samples represent an average concentration greater than 

one thousand times the levels observed in the water phase for the 

DDD and DDT components. The high concentrations of DDD may 

result from the degradation of DDT. These data indicate a situation where DDT entered the water medium at a time in the past, 

but ended up in the sediments as a persistent residue. There undoubtedly has been a buildup over a time period, but the absence 

of previous data precludes any quantitative conclusion.

SUMMARY AND CONCLUSIONS

The Stony Brook basin drains part of the Piedmont Lowland 

section of the Piedmont physiographic province in west-central 

New Jersey. This section has been described (Anderson and 

George, 1966) as the State's heaviest nonurban sediment producer. Cooperating agencies determined that it was necessary to 

identify the source, magnitude, and trend of sediment transported 

in and from the basin and to describe the effect of land-management practices, urban growth, and development of seven P.L. 566 

retention reservoirs on the sediment yield from the basin.

Observation of sediment yield at Princeton (table 3) and at 5 

subbasin sampling sites (table 4) range from roughly £5 to 400 

tons per sq mi. During 1956-70, about 127,000 tons of suspended 

sediment was transported by Stony Brook into Carnegie Lake at 

an annual rate of about 8,800 tons, or 200 tons per sq mi. About 

90 percent of this material, which consists of 40 percent clay, 55 

percent silt, and 5 percent sand, was carried during storms that 

transported at least 1 ton of suspended sediment from th« basin.

Land use has changed in two prominent ways: an increase in 

the percentage of idle land and cash-crop farming and an increase 

in urbanization. Based on surveys made in 1957 and 1970, there 

was a 0.5 percent net increase of idle land, nearly a P percent 

decrease in farmlands, and a 4.6 percent increase in urVan land. 

Increases in idle areas were mainly in the northwestern part of 

the basin. Farmlands have decreased over the entire b*\sin, but 

mostly in the western part. The basin is being urbanized throughout, but somewhat more rapidly south of Hopewell and1 west of 

Princeton.

Trend analyses indicate that a greater suspended-sedinent load 

was transported by the Stony Brook at Princeton during the
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L31

earlier years of this investigation (1956-61) than during the more 

recent years (1967-70). Also, in a multiple-regressior analysis 

of the same data, the partial-regression coefficient for a particular 

storm was found to be negative, thus indicating that sediment 

concentration decreased with increasing period of sediment record. These analyses can be interpreted as evidence of a trend 

toward decreasing sediment load per unit discharge with time.

An upward trend in sediment discharge at Princeton, during 

the early period investigated (1956-61), is probably the consequence of farming, highway construction, reservoir cor^truction, 

and urbanization. Earth moving related to highway and reservoir 

construction and to developing urban areas is a potential source 

of higher sediment yields. Similarly, the continued reworking of 

the land surface by farming together with a general lack of covercrop practices, particularly in areas where cash-cropping prevails, 

also is a potential source of increased erosion and sediment transport. Construction of three of seven P.L. 566 sediment-retention 

reservoirs prior to 1961 exposed soils to erosion and increased 

the potential for sediment transport. The influence of these and 

other factors probably explains the upward trend noted in the 

1956-61 period.

During the later period (1967-70), sediment discharge per unit 

water discharge decreased. The decrease can be attributed to several factors. Exposure of soils through earth moving associated 

with construction and during developmental phases of urban 

areas generally results in temporary high sediment yields. When 

this stage has passed, an area becomes relatively stable and sediment yields become lower. An economic slowdown in construction 

and urban development during this period certainly contributed 

to this downward trend. Also, while temporary local increases in 

sediment yields can be attributed to the construction of one P.L. 

566 sediment-retention reservoir in 1968-69, the combined operation of six completed reservoirs, based on a trap-efficiency study 

of one, Baldwin Lake, is estimated to reduce sediment discharge 

at Princeton by 20 percent.

Interpretation of trends in sediment discharge durir<? 1962-66 

is extremely difficult, complicated by the installation of three 

reservoirs, continued land-use changes, and a drought. Although 

it was not possible to separate the influences of reservoir construction and urbanization, they undoubtedly produced higher 

than normal sediment yields. Concurrently, sediment discharges 

at Princeton were reduced almost tenfold, from 11,121 tons in 

1961 to 1,625 tons in 1965, during the drought. The total effect of 

these factors complicated the interpretation of sediment trends.
L32 SEDIMENTATION IN SMALL DRAINAGE BASINS

The drought is over, as is the economic slowdown. Whether the 

downward trend in sediment discharge continues remains to be 

determined. It seems likely, however, that completion of the sediment-detention reservoirs, together with the technical knowledge 

now available for sediment and erosion control, will work together for reduction of sediment discharge.

Calcium sulfate type water predominates in the basir's streams. 

Dissolved-solids content ranges from 100 to 250 mg/1, hardness 

from 75 to 200 mg/1, and pH from 6.7 to 8.1. Spectrographic 

analyses indicate trace amounts of aluminum, barium, toron, chromium, copper, iron, lead, lithium, manganese, molybden um, nickel, 

rubidium, strontium, titanium, and vanadium in addition to those 

elements routinely measured in chemical analyses, including sodium, potassium, calcium, magnesium, bicarbonate, sulfate, chloride, and nitrate. Results of analyses for 10 chlorinr.ted hydrocarbon insecticides also are given. In general, higher amounts of 

these insecticides, principally members of the DDT fp.mily, were 

observed in water during a spring sampling period, perhaps indicating agricultural input, and in the bottom sediments during 

both spring and fall samplings, indicating that pesticides are persistent in bottom sediments. However, dredging, scouring during 

high-flow periods, or other disturbance of bed materials are likely 

to move bottom sediments.

REFERENCES

Anderson, P. W., 1970, Occurrence and distribution of trace elements in New 

Jersey streams: New Jersey Div. of Water Policy and Supply, Water 

Resources Circ. 24, 24 p.

Anderson, P. W., and George, J. R., 1966, Water-quality characteristics of 

New Jersey streams: U.S. Geol. Survey Water-Supply F^per 1819-G, 

48 p.

Anderson, P. W., and McCall, J. E., 1968, Urbanization's effec4" on sediment 

yield in New Jersey: Jour. Soil and Water Conserv., v. 23, no. 4, p. 

142-144.

Bascom, F., and others, 1909, Description of the Trenton quadrangle [New 

Jersey-Pennsylvania] : U.S. Geol. Survey Geol. Atlas, Folio 167.

Colby, B. R., 1956, Relationship of sediment discharge to streamflow: U.S. 

Geol. Survey open-file rept., 170 p.

Davis, S. N., and DeWiest, R. J. M., 1967, Hydrogeology: New York, John 

Wiley and Sons, 463 p.

George, J. R., 1963, Sedimentation in the Stony Brook basin, New Jersey, 

1956-59: U.S. Geol. Survey open-file rept., 71 p.

Guy, H. P., 1957, The trend of suspended-sediment discharge cf the Brandywine Creek at Wilmington, Delaware, 1947-55: U.S. Geol, Survey openfile rept., 55 p.

 1964, Analysis of storm-period variables affecting stream sediment 

transport: U.S. Geol. Survey Prof. Paper 462-E, 46 p.
SEDIMENT YIELDS, STONY BROOK BASIN, NEW JERSEY L33

Lane, E. W., and others, 1947, Report of the subcommittee on sediment terminology: Am. Geophys. Union Trans., v. 28, no. 6, p. 936-938.

Mansue, L. J, 1970, Sediment yields as affected by land use and retention 

practices: Am. Soc. Agr. Engrs., Proc. Annual Meeting.

Moore, W. R., Ferris, H. J., and Koszchyn, J., 1952, Report on sedimentation 

in Carnegie Lake, Princeton, New Jersey: U.S. Soil Conserv. Service 

Rept. SCS-TP-109, 20 p.

Palmer, A. C., and others, 1957, A regional planning plot study of the 

Millstone watershed: Rutgers Plan. Service, 83 p.

Praeger, Kavanagh, and Waterbury, 1968, Supplementary report of proposed restoration of Carnegie Lake, Princeton, New Jersey: New York, 

Praeger, Kavanagh, and Waterbury Consultants, 13 p.

Searcy, J. K., and Hardison, C. H., 1960, Double-mass curves, U.£ Geol. 

Survey Water-Supply Paper 1541-B, p. 31-66.

Stony Brook-Millstone Watersheds Association and other Sponsoring? Organications, 1956, Work plan agreements for the Stony Brook watershed: 

Stony Brook-Millstone Watersheds Association, 45 p.

U.S. Geological Survey, 1967, Engineering geology of the northeast corridor, 

Washington, D.C., to Boston, Massachusetts, Bedrock geologv: U.S. 

Geol. Survey Misc. Geol. Inv. Map I-514-A, Sheet 3.

U.S. Soil Conservation Service, 1953, Land-capability class (New Jersey): 

U.S. Dept. Agriculture, Sheet nos. 1-7.

 1959, Report of sedimentation study on Carnegie Lake, Princeton, 

New Jersey: U.S. Dept. Agriculture, 3 p.

U.S. Weather Bureau, 1963, Climatography of the United States: U.S. Dept. 

of Commerce, no. 84, p. 181.

* U.S. GOVERNMENT PRINTING OFFICE: 1974 543--S83/72