Record Low Tide of 

December 31,1962 

On the Delaware River

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1586-E

Prepared in cooperation with the City of 

Philadelphia Heater Department, the Corps 

of Engineers, Department of the Army, and 

the New Jersey Department of Conservation 

and Economic Development
Record Low Tide of 

December 31,1962 

On the Delaware River

By A. C. LENDO

HYDROLOGY OF TIDAL STREAMS

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1586-E

Prepared in cooperation with the City of 

Philadelphia Water Department, the Corps 

of Engineers, Department of the Army, and 

the New Jersey Department of Conservation 

and Economic Development

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1966
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 15 cents (paper cover)
CONTENTS

Page

Abstract___ ______________________________________________________ El

Introduction. _ -_---_-_---_-_-_-___-____________-__---_-----_-_-___ 1

Data available_____________________________________________________ 3

Data on record low tide_ _-_-_-___________-_-_-____---____-___-_ 3

Quality-of-water data._________________________________________ 8

Long-term records.________________-_---_-_________-_---_-_-_-_ 8

Analysis of data on record low tide._________________________________ 8

Effect of wind on tide___________-____________-.___---_-_---___-_.___ 10

Analysis of long-term records of low tides on Delaware River at Philadelphia, Pa___-_____---___-____-_____-___-_---__--___-__----_..-_ 13

Effect of the record low tide on water quality.________________________ 15

Summary and conclusions,______________-__-_--____---_-_-_.-__--__ 18

Selected references.-____--__________-____-_-_____________----____-- 19

ILLUSTRATIONS

Page 

FIGURE 1. Map of tidal reach of Delaware River.___________________ E2

2. Photographs of Delaware River near Wilmington, Del.,

during low tide of December 31, 1962__________________ 4

3-8. Graphs:

3. Tidal elevations of Delaware River at Delaware 

City, Del., and opposite Delair, N.J., during 

period December 30, 1962 to January 1, 1963. __ 7

4. Low tide of December 31, 1962, on the Delaware

estuary ______________________________________ 10

5. Comparison of wind speed and low tide elevation,

December 29, 1962, to January 1, 1963___-_-_-_- 12

6. Minimum low tide frequency curve for Delaware

River at Philadelphia, Pa___________-_---_-_-_- 14

7. Daily maximum chloride concentrations of Delaware River at Reedy Island Jetty, Del., Delaware 

Memorial Bridge, Del., and Chester, Pa., December 1962 and January 1963_.._.__._.----.-._.-. 16

8. Daily minimum dissolved-oxygen concentrations of 

the Delaware River at pier 11 North, Philadelphia, 

Pa., and Chester, Pa., December 1962 and January 

1963.___-___--__-___________-___-_-_-____--_ 18

in
IV CONTENTS

TABLES

Page

TABLE 1. Elevations of low tide on December 31, 1962, on the Delaware River. ________________________________________ E7

2. Annual minimum low tides on Delaware River at Chestnut

Street pier, Philadelphia, Pa_--_-----___----___-_-___- 9

3. Total number of days in each month, for period 1932-62, 

when low low tide reached indicated elevation on Delaware River at Chestnut Street pier, Philadelphia, Pa____ 14
HYDROLOGY OF TIDAL STREAMS

RECORD LOW TIDE OF DECEMBER 31, 1962, ON THE 

DELAWARE RIVER

By A. C. LENDO

ABSTRACT

The lowest known low tide in the recorded history of the Delaware River 

estuary occurred on December 31, 1962. The primary cause for this low tide was 

the strong, persistent wind from the northwest which resulted from a stationary 

low-pressure area over Maine and the Maritime Provinces and a high-pressure 

area over the Great Lakes. The direction of the wind, blowing downstream on 

the Delaware Bay forced huge volumes of water out of the Delaware Bay and, 

at the same time, lowered the ocean tide levels offshore along the coast of the 

Atlantic Ocean; these effects combined to produce the lowest known low tide 

in the Delaware estuary. The magnitude of this tide was particularly significant. At the Chestnut Street pier, Philadelphia, Pa., where records have been 

collected since 1899, the low tide of December 31 was 1.7 feet lower than the 

previous minimum low tide.

This report presents the data that were collected on this phenomenally low 

low tide, discusses its causes, and describes its effects on navigation, water 

supply, and quality of the estuarine water. The frequency of abnormally low 

tides is evaluated for different degrees of severity at Philadelphia.

INTRODUCTION

Persistent northwest wind on December 30-31,1962, swept down the 

Delaware River and Bay (see fig. 1) and offshore over the Atlantic 

Ocean The wind averaged 23 miles per hour for the 48-hour period 

at Philadelphia, Pa., and 26 mph at Wilmington, Del. The full 

strength of this wind in the direction of flow during ebbtide in the 

Delaware Bay and against the return flow during floodtide caused 

large amounts of water to flow out to sea during each tide cycle. 

Meanwhile, wind blowing from offshore lowered ocean tide levels to 

near record low. The combined effects of the wind caused huge volumes of water to drain out of the Delaware estuary. Before this 

northwest wind subsided, the Delaware estuary had a low tide on 

December 31 that was considerably lower than any previously recorded.

El
E2

76°00'

HYDROLOGY OF TIDAL STREAMS

75°30' 75°00' 74° 30'

40° 00'

 Wilmington

39° 00'

Head of tidal reach

BURLINGTON-BRISTOL BRIDGE

PENNSYLVANIA 

TACONY-PALMYRA BRIDGE

Delair 

Camden

WALT WHITMAN 

BRIDGE

Philadelphia 

Chester

DELAWARE MEMORIAL 

BRIDGE

Delaware City

Reedy Point/Reedy lsland JettV

NEW JERSEY

DELAWARE 

MARYLAND I

5 0 5 10 15 MILES

DELA WARE 

BAY

Breakwater cape May 

Ha rbor

Cape Henlopen

Delaware River and 

Bay Monument at 

Listen Point

FIGURE 1. Tidal reach of Delaware River.

The bed of the Delaware Eiver was exposed, for the first time 

known, as much as 200 feet from the river banks (fig. 2). Channel 

and berthing; depths were reduced sufficiently in some places to affect 

navigation, and many boats were stranded on the mud. Water-supply 

intakes for industries, powerplants, and municipalities were unexpectedly out of water for as long as 6 hours. The loss of water supply 

caused shutdowns, posed a fire hazard, and caused deep concern 

wherever uninterrupted operations had to be maintained. Arrangements for use of standby water supply were necessary. Some plants 

managed to continue operations, with loAver efficiency, by reuse of the 

effluent water which was fortunately pooled near the outfall of their 

water-supply intake.

The effect of the record low tide on the quality of the tidal waters 

was noteworthy. A significant decrease in salinity was recorded as 

the huge volume of brackish water moved out of the Delaware River 

estuary and was replaced by the fresher water flowing from the upper
RECORD LOW TIDE ON DELAWARE* RIVEiR E3

tidal reach. When the wind subsided there was a surge of highly 

saline water from the ocean and bay, and the chloride concentration 

in the lower tidal reaches of the river continued abnormally high for 

2 or 3 weeks.

The wind from the north brought the first severe cold weather of 

that winter. The freezing weather, 18°F average for December 30 

and 8°F average for December 31, caused many of the recording tide 

gages and water-quality monitoring instruments to be inoperative 

because of frozen intake lines or float chambers. Other instruments 

failed because the tide level dropped below their operating range. 

The low tide left no marks of the elevation that it reached, in contrast 

to many high-water marks observed following major floods or 

maximum high tides. Thus, to better document this rare occurence, 

visits were made by Geological Survey personnel to many Federal, 

municipal, and industrial establishments along the Delaware estuary. 

The information and data that were collected on the record low tide 

of December 31, 1962, are presented in this report. In addition, 

comparative data on previous abnormally low tides and annual minimum tides since 1899 at Philadelphia, Pa., are included in the report. 

These data will be useful for various studies; particularly, they show 

that the December 31, 1962, low tide was a very rare occurrence.

This work is a special extension of cooperative studies of the 

Delaware estuary by the U.S. Geological Survey with joint participation by the City of Philadelphia Water Department, the U.S. Army 

Corps of Engineers, and the Division of Water Policy and Supply of 

the New Jersey Department of Conservation and Economic Development. The field investigations and preparation of this report were 

under the general direction of J. E. McCall, district engineer. The 

Philadelphia office of the U.S. Geological Survey Quality of Water 

Branch, N. H. Beamer, district chemist, assisted in the investigations 

and furnished the information and data on the quality of the water. 

Acknowledgment is also made to the many industries and municipal 

agencies that provided valuable assistance, data, and information.

DATA AVAILABLE

DATA ON EECOED LOW TIDE

A continuous record of the tidal stages on December 31 was not 

available for most of the recording gages along the Delaware estuary. 

Three days after the occurrence of the abnormally low tides on December 31, preliminary data on the minimum tide were available at 

only a few locations in the vicinity of Philadelphia, Pa. Of the four 

recording gages on the estuary operated at that time by the U.S. 

Geological Survey and cooperating agencies, only one, opposite Delair, 

N.J., operated satisfactorily throughout the period of the record low
E4 HYDROLOGY OF TIDAL STREAMS

FIGURE 2. ^Delaware River near Wilmington,

tide. The other gages, at Marine Terminal, Trenton, N.J.; Palmyra, 

N.J.; and Toresdale, Pa., failed to record the low tide. Similarly, for 

several locations elsewhere on the Delaware estuary where records were 

collected by other agencies, the data were incomplete.

The minimum water level which occurred on December 31 was below 

the recording limit of many of the gages, even though most were 

designed to record well below the lowest low tide that had previously 

been known. The extreme cold, which caused gage wells to freeze or 

recorders to be inoperative, was also a factor in the loss of record. At 

most places where the stage of the low tide was determined, the 

measurement was obtained by outside staff or reference point readings, 

which were obtained under extremely difficult and hazardous conditions. It was impossible to observe or obtain outside readings to define 

the minimum stage at a few locations because surface ice had settled, 

as the water receded, until it rested on the river bottom.
RECORD LOW TIDE ON DELAWARE. RIVEiR E5

Del., during low tide of December 31, 1962.

Iii spite of the difficult conditions, later visits disclosed that data on 

the record low tide wTere collected by several private companies and at 

municipal installations. At three of these locations, a continuous 

record of the abnormally low tides was collected by use of a pressuretype gage. For these locations, the inside-outside stage relationship 

had to be investigated for possible errors in the recorded minimum 

stage. At other locations where the wTater level fell below the recording limit of the continuous gages, readings wT ere taken from reference 

points by company employees at or about the time of the low tide. 

Additional data were thus available wherever the elevation of the 

reference point was known or could be determined.

Many different local datums were used in determining the stages of 

the low tide. The stage of the tide at each location was converted to 

feet above or below mean sea level datum of 1929, for this report. 

Verification or determination of the local datum in use was difficult

206-787 O '66 2
E6 HYDROLOGY OF TIDAL STREAMS

in places. Some of the more commonly used datums and their 

conversion to sea level are as follows:

Above (+)

Datum or below ( )

mean sea 

level (feet)

Delaware River (Corps of Engineers)________________ 2. 9

City of Philadelphia___-______-_----_-_-_---------- +5. 6

Mean low water of 

Trenton, N.J_._________________________ -1. 6

Burlington, N.J_._________________________ - 1. 8

Philadelphia, Pa________________________ -2. 1

Wilmington, Del________________________ __ -2. 0

Delaware City, Del____________-_---_----_--_- 2.1

Many different systems have been used to identify the locations on 

the Delaware River to which the data refer. The Delaware River 

Basin Commission recently promoted the adoption of a uniform rivermile .system, which was reviewed and approved by the U.S. Army 

Corps of Engineers and other government agencies.

Mile 0 for the adopted mileage system is the intersection of a line 

between Cape May Light and the tip of Cape Henlopen with the centerline of the navigation channel. Distances from mile 0 are measured 

along the centerline of the main navigation channel from Delaware 

Bay to Bridge Street Bridge at Trenton, N. J. Thence, to the head of 

' the main stem of the Delaware River, the river mileages correspond 

to distances measured along the State boundaries which approximate 

the centerline of the Delaware River.

The elevations of the December 31 low tide and the stationing of the 

locations, which were referenced to the adopted mileage system, are 

given in table 1. The stationing to a point not on the line of measurement was determined by the mileage to the point of intersection of a 

line through the point perpendicular to the line of measurement.

The lowest water level that was reached on December 31 was an instantaneous minimum because the river level was continuously 

changing, due to the tidal fluctuations in the estuary. To illustrate the 

length of time that the river level was at the lowest elevation, or below 

various elevations, and the time of occurrence of the minimum water 

level along the estuary, graphs of the tide levels that occurred at two 

locations during the 3-day period, December 30, 1962, to January 1, 

1963, are shown in figure 3.

One of these locations is on the Delaware River opposite Delair, 

N.J., \vhere the U.S. Geological Survey operates a gage at the Richmond Station of the Philadelphia Electric Co. The other is at 

Delaware City, Del., where the Tidewater Oil Co. collected and furnished the record. Note that even the high tides of December 31 failed 

to reach the normal or mean low water level.
RECORD LOW TIDE ON DELAWARE RIVER E7

TABLE 1. Elevations of low tide on December 31, 1962, on the Delaware River

[Stationing: Mile 0, intersection of the line between Cape May Light and tip of Cape Henlopen with the

centerline of navigation channel]

Location

Public Service Electric & Gas Co., Hamilton Township, N.J _________

U.S. Steel Corp., Falls Township, Pa_ ____________

Colorado Fuel & Iron Corp., Roebling, N.J _

Lower Bucks Municipal Authority, Tullytown, Pa__ 

Public Service Electric & Gas Co., Burlington, N.J_ 

Schute & Koerting, Cornwells Heights, Pa

Weyerhauser Co., Delair, N.J _ _ _

U.S.G.S. gage at Phila. Elec. Co. (Richmond Sta.) 

opposite Delair, N.J_ _ _

Pier 9 North, Philadelphia, Pa__ ___________ _ _

Pier 4 South, Philadelphia, Pa__

Texaco, Inc., Westville, N.J__ _ _

Phila. Elec. Co. (Schuylkill Sta.), Philadelphia, Pa 

Fort Mifflin, Philadelphia, Pa_____

Phila. Elec. Co. (Eddystone Sta.), Philadelphia, Pa_ 

Phila. Elec. Co. (Chester Sta.), Chester, Pa

Wilmington Marine Terminal, Wilmington, Del

Atlantic City Power & Light Co., Deepwater, N.J__ 

Tidewater Oil Co., Delaware City, Del _ _ _

Reedy Point, Del_ _____ ______

Lewes (Fort Miles), DeL _

Atlantic City, NJ_ ____ _

Stationing 

(miles)

130. 4

127. 8

125. 1

122.3 

117. 5 

113. 8

104. 4

104. 2

100. 1

99. 8

Q4 4

0)

91. 3

84. 9 

81. 3

70. 7

68. 6 

60. 7

58. 9

(')

(3)

Feet below 

mean sea 

level

8. 6

11. 0

9. 0

10. 9 

9. 1 

10. 0

8. 4

8.6

8. 8

8.5

0 ft

9. 0

8.7

9.5 

9.0

9. 1

9. 1

8.5

8. 6

4. 5

4. 6

Time 

(24 hour)

1500

1500

1500

1445 

1445

1430

1215

1200 

1145

1130 

1000

0600

0400

1 On Schuylkill River, 6.5 miles upstream from mouth.

2 On Breakwater Harbor.

3 On Atlantic Ocean.

TIME, 24-HOUR CLOCK

FIGURE 3. Tidal elevations of Delaware River at Delaware City, Del., and opposite Delair, 

N.J., during period December 30, 1962, to January 1, 1963.
E8 HYDROLOGY OF TIDAL STREAMS 

QUALITY-OF-WATEE DATA

Records of chloride concentrations, dissolved-oxygen content, and 

temperature have been collected since 1949 at several sites along the 

estuary in cooperation with the City of Philadelphia Water Department and the Delaware Geological Survey. Analysis of these records 

indicated the changes in water quality which occurred during and 

after the record low tide.

The daily maximum chloride concentrations and minimum dissolvedoxygen concentrations for December 1962 and January 1963 are shown 

in figures 7 and 8. The dissolved-oxygen recorders were inoperative 

December 31, 1962, to January 2, 1963, because of the low water and 

the freezing temperatures. The changes in dissolved oxygen however 

can be estimated by observing the records before and after the event.

LONG-TEEM BECORDS

In addition to inquiries for facts on the December 31 low tide, a 

search for past records of low tides was successful. Thus, the magnitude and frequency of occurrence of the December 31 low tide can be 

compared with low tides of previous periods.

Most of the recording-gage records are of short term. Data on past 

abnormally low tides are unfortunately incomplete for some of the 

longer records because measuring gages have frozen or otherwise malfunctioned. The earliest records were collected on the Delaware River 

at Philadelphia, Pa. An unusually long record, since 1899, has been 

collected by the Port Division, City of Philadelphia, at the Chestnut 

Street pier, which is also known as pier 4 South. The annual minimum low tide at this gage is given in table 2. In addition, a tabulation of the low low tides each day for the calendar years 1932-62 was 

furnished by the Port Division for study and analysis.

For the occasional periods of no record at pier 4 South, the records 

collected by the U.S. Coast and Geodetic Survey at pier 9 North, 

Philadelphia, Pa., since 1922, were used. The 1922 minimum low tide 

was not available at either gage, but other nearby tide-gage records 

were used for a fairly accurate estimate.

ANALYSIS OF DATA ON RECORD LOW TIDE

The low tide data given in table 1 are plotted in figure 4. The profiles along each bank of the river were drawn from the plotted data, 

and the lower elevations were overaged wherever there was wide variation.

Field checks indicated that the variation was mostly due to local 

conditions in the vicinity of the point of observation that is, whether 

the site was in a sheltered or open reach of the river, on the windward
RECORD LOW TIDE GIST DELAWARE, RTVEiR E9

or leeward side of a bridge or pier, or on a particular bank of the river. 

A significant difference resulting from local conditions can be demonstrated by comparing the elevations at the Pennsylvania bank of the 

river with those on the New Jersey side of the river in the reach from 

Burlington-Bristol Bridge to Trenton, N.J. (fig. 4). The wind blew 

across the flat and open spaces on the windward (Pennsylvania) side 

of the river, and thence, its force undiminished, directly across the 

river in this reach. The force of the wind caused the water to pile up 

as much as 2 feet on the lee shore, and this situation resulting in these 

pronounced differences in elevation.

TABLE 2. Annual minimum low tides on Delaware River at Chestnut Street pier,

Philadelphia, Pa.

Calendar 

year

1899-.. 

1900_ ____

1901_____

1902_____

1903__.__

1904. ____

1905. __ 

1906. -___

1907_____

1908_ ____

1909_____

1910____.

1911_____

1912_____

1913_____

1914_____

1915_____

1916__-__

1917_-___

1918_____

1919_____

1920_ ____

1921_____

1922. ...

1923_____

1924_____

1925_____

1926_____

1927___._

1928____

1929_____

1930. __ 

Date

Sept. 21._________

Nov. 10__________

Feb. 6_-_________

Jan. 11 __ ___

Nov. 14__________

Nov. 13____ ___ _

Apr. 22_ _ _______

Nov. 5

Feb. !___________

Dec. 17. --__---_

Mar. 16_

Dec. !___________

Mar. 7 _ _

Dec. 15_______ _

Apr. 15... _______

Mar. 19__________

July 21 _ _________

Mar. 29__________

Feb. 27__________

Jan. 26_

Jan. 16 ________

Feb. 15. ----- __

Nov. 17__-_______

Dec. 28. __ __ _

Jan. 16 ___ ____

Jan. 21 _________

Mar. 8___

Dec. 2. ______ ___

Feet 

below 

mean 

sea level

"> Q

4. 7

5.3

4. 6

4. 9

4. 1

3.2

4. 5

3. 8

4. 0

4 6

5. 6

4. 4

4. 2

5. 4

6. 4

4.8

4. 2

4. 6

3. 6

6. 4

5. 1

4. 2

1 4. 5

2 5. 4

5. 5

e Q

5. 9

4. 7

4. 8

5. 8

5.0

Calendar 

year

1931__.._

1932_____

1933_ .._

1934. ____

1935_____

1936 ____

1937___._

1938_____

1Q3Q

1940_____

1941_____

1942_____

1943_____

1944_____

1945_____

1946_____

1947. ____

1948_____

1949_____

1950_____

1951_-___

1952_____

1953_____

1954. ____

1955_-__-

1956_____

1957_____

1958_-___

1959_____

1960_____

1961_____

1962. ____

Date

Dec. 26. __._.._..

Mar. 8 _ - _ 

Dec. 29 _________

Jan. 30. _______

Jan. 14_ ______

Jan. 25-____--__-

Feb. 3____-__._ 

Feb. 28_________-

Jan. 26. _ ______

Feb. 15, Mar. 26 _.

Mar. 19__________

Feb. 22 _ _______

Dec. 11 ________

Feb. !___________

Jan. 25____--____

Dec. 2_ ________

Feb. 11__________

Jan. 28_ _________

Mar. 1 _ Mar. 10___----__-

Dec. 16_____-._-_

Feb. 12_______.__

Feb. 10__________

Jan. 28, Dec. 23. __

Mar. 28----------

Dec. 30__. -------

Jan. 24 _________

Nov. 30_---__ 

Jan. 21_______-_-

Dec. 15__--. _

Dec. 31__ _--_-__

Feet 

below 

mean 

sea level

5. 5

6.4

4. 9

5.0

4. 3

4. 4

3. 6

2 5. 9

6. 8

4. 6

2 5. 7

5.4

5. 8

5. 6

6. 8

6. 6

6.7

4. 8

4. 3

5. 0

4. 2

4. 2

4. 1

4. 0

5. 0

4. 3

5. 3

6. 7

4. 6

4.7

8. 5

1 Estimated.

' At pier 9 North.
E10 HYDROLOGY OF TIDAL STREAMS

-4

'wT

~° 'E 

<a E

Jm

'ro fO 

Q; 00

'c c

K3 O

"^ s!

1

^^

x -* '

Ele

Elevat

/

~o a?

co oq

O T-l

s- M 

13 -0

00 '£ 

00

!

EXPLANATION

vation at east bank of river (N.

x

on at west bank of river (Pa. or

^* i

TO .2

Cu ^

C ^ '

o a,

m 

1

CD

E E

. § K)

5 £,

^ M

m

i

x

X

O)

01 E 

So;

0-3 

o

E

l

J.)

Del.)

_^x

 *-'^~

03 (/)

|E

s oo

CD ID

"° "aT

* ao

"5 '^ 

Q 00

I

X

I«

 0-2 

g E

_w O)

-o 10

^.1 

1

-12

-16

140 130 120 110 100 90 80 

MIDCHANNEL STATIONS, IN MILES

70 60 50

FIGURE 4. Profile of low tide of December 31, 1962, on the Delaware estuary.

On the average, the low tide was about 9 feet below mean sea level, 

datum of 1929, or 7 feet below normal (mean low water) from Trenton, N.J., to Reedy Point, Del., except along the Pennsylvania bank in 

the reach upstream from the Tacony-Palmyra Bridge where it was as 

much as 11 feet below mean sea level. No data on the minimum tide 

on the Delaware Bay have been found except for that at Breakwater 

Harbor, Del.; however, this tide may be approximated on the basis that 

the minimum tide was 8.6 feet below mean sea level at Reedy Point, 

Del., and about 4.5 feet below mean sea level at Breakwater Harbor, 

Del.

EFFECT OF WIND ON TIDE

The principal factors which upset the normal tidal variations in 

the Delaware estuary are wind and floods on the inflow streams. 

The most significant effect of the flood was to cause high inflows 

on the Delaware River at Trenton, N.J. As this flood discharge 

and the inflow from streams downstream moves seaward, the effect 

of the volume of water is less noticeable as the tides moving up and 

down the estuary become greater. From the vicinity of Philadelphia, 

Pa., to the sea, flood discharges into the estuary are soon dwarfed by 

the huge tidal volumes of flow.

During the period December 30, 1962, to January 1, 1963, the inflow 

was low; for example, the flows of the Delaware River at Trenton, 

N.J., averaged 3,900 cubic feet per second for the 3-day period. These
RECORD LOW TIDE ON DELAWARE RIVER Ell

low inflows had no significant effect on the tidal variations. The 

major cause of the record low tide in the estuary was the unusual 

strength of the northwest wind and its direction which concides with 

the ebb flow and these opposed the floodflow during each tide cycle.

Figure 1 shows that the ebb or downstream flow in the Delaware 

estuary from Trenton, N. J., to the Atlantic Ocean is in a southeasterly 

direction for about 5 miles, thence in a generally southwesterly direction to the vicinity of Delaware City, Del., where it again changes 

nearly 90° to flow in a southeasterly direction in the lower Delaware 

River and Bay.

The sweep of the wind directly down the widest part of the 

estuary and bay in the 60-mile reach from Delaware City, Del., to the 

sea is probably the dominant cause of the record low tides in the 

Delaware River. An important contributing factor was the abnormally low, but not record low, tide levels that were occurring along the 

Atlantic coast, also as a result of the northwest wind.

At Atlantic City, N.J., the low tide elevation of December 31 was 

4.6 feet below mean sea level; however, the record low tide at this location was 0.8 foot lower in March 1932. At Breakwater Harbor, Del., 

opposite the mouth of Delaware Bay, the low tide elevation was 4.5 

feet below mean sea level on December 31. Low tides as much as 0.3 

foot lower have been recorded at Breakwater Harbor during 5 years of 

the 24 years of records, 1919-23, 1936-39, 1947-50, and 1952-62, collected by the U.S. Coast and Geodetic Survey.

As the floodtide began, following the minimum low tide at 0400 

hours on December 31 at Breakwater Harbor, the sharply increasing 

northwest wind caused an additional drag force which retarded the return flow into the bay. Also, as the wind increased to its maximum 

speed, it blew huge additional volume of water down the bay toward 

the incoming tide. As a result of the momentum of the body of water, 

augmented by the wind, the receding tide levels in the upper bay fell 

considerably lower than those in the vicinity of the mouth of the bay. 

This effect became even more pronounced farther up the estuary, and 

the lowest tides, nearly 11 feet below mean sea level, occurred below 

Trenton near the head of tide.

In figure 5, the successive 6-hour average wind speed at Wilmington, 

Del., and the low tides at Delaware City, Del., are shown for the period 

December 29, 1962, to January 1, 1963. The wind was variable and 

light for the first 17 hours of December 29, and the tides were normal. 

Thereafter, for the period shown, the wind was persistently from the 

northwest. As the wind speed increased, the tide levels became progressively lower, and similarly, as the speed diminished, the tides returned gradually to normal.
E12 HYDROLOGY OF TIDAL STREAMS

SIX-HOUR AVERAGE WIND SPEED, IN MILES HOUR PER AT WILMINGTON, DEL

CO I\J4 i-1 O 0C

Note: Variable dir 

wind prior to 18 

_ December 29; f 

northwest there

' '

action of 

00 hours

after , 

h-l L-

< UJ

ujQQ > ?

zb ^ 

00

_JLLJ uj Q: 4 

> <

-1 

<uj 6

^ E-10

+ +

EXPLAh ATION

Low tide elevation at^

time of oc :urrence

Mean low water

+

+

Dec. 29, 1962 Dec. 30 Dec. 31 Jan. 1, 1963

FIGURE 5. Comparison of wind speed and low tide elevation, December 29, 1962, to

January 1, 1963.

Figure 5 shows that wind speeds of 20 mph before and after 

minimum tide resulted in low tides about 1 foot below normal or mean 

low water. As the wind speeds increased above the 20-mph average 

on December 30 and 31, the effect on the tide levels became more 

significant. The increase in the average wind speed from 28 to 38 

mph on December 31 resulted in the record low tide, which was 6.4 

feet below normal at Delaware City, Del., and about 4 feet lower than 

the previous low tide during the latter part of December 30. The 

effects were apparently cumulative, with more water flowing into the 

ocean on each ebb tide than returned on the floodtide until the afternoon 

of December 31, as shown in figure 3.

The wind thus caused an unusual and huge volume of brackish 

water to drain from the bay into the ocean. At the time of the 

minimum low tide at 0400 hours on December 31 at Breakwater Harbor, the water level was about 4 feet below mean sea level and falling 

at Delaware City (see fig. 3), 60 miles upstream. At this time, just 

before return flow into the bay in floodtide, there had been a drainage 

of approximately 80 billion cubic feet more in this reach of the bay
RECORD LOW TIDE ON DELAWARE RIVER E13

than at normal mean low water. Similarly, as the tide levels fell to a 

record low in the upper bay, billions of cubic feet of the fresher water 

in the upper estuary flowed into the Delaware Bay.

The 25-mile reach from Tacony-Palmyra Bridge to Trenton, N.J., 

which may be described as a "fresh-water lake," has a capacity of about

3 billion cubic feet at mean low water. At the time of the record low 

tide at Tacony-Palmyra Bridge, there was a depletion of approximately U/4 billion cubic feet of water in the reach, or nearly a one-half 

reduction in the usual contents of this "lake" at normal low tide.

In the 65-mile reach from Delaware Memorial Bridge to Trenton, 

N.J., the mean low water capacity is about 11 billion cubic feet. This 

volume was reduced to about 7 billion cubic feet at the time of the 

minimum low tide on December 31. The depletion of approximately

4 billion cubic feet in this reach was nearly equal to the volume required to fill Neversink Eeservoir in the upper Delaware Kiver basin.

ANALYSIS OF LONG-TERM RECORDS OF LOW TIDES ON 

DELAWARE RIVER AT PHILADELPHIA, PA.

A study of the annual (calendar year) minimum low tides given in 

table 2 shows that the December 31 low tide was 1.7 feet lower than 

the previous minimum that occurred on January 26,1939, and January 

25, 1945, 'and the lowest in 64 years of record. The magnitude of this 

low tide compared to the previous minimum indicates that its recurrence interval may be considerably greater than a 64-year period.

The frequency was based on 64 years of record at Philadelphia, Pa., 

and plotted in figure 6. A straight-line extension of the graph 

indicates that the minimum low tide that occurred on December 31 

might be expected, on the average, to recur about once every 150 years. 

This extrapolation is, of course, highly speculative and could be considerably in error. The tendency toward rising sea levels in recent 

decades, and possible changes in wind patterns, could easily upset the 

extrapolation, which also depends on the unproven validity of a 

straight-line extension.

In addition to the yearly minimums, the daily low low tides for the 

calendar years 1936-62 were available. There are usually two low 

tides each day; however, only the lower of these, that is, the low low 

tide, was included in table 3. The other, or high low tide, was usually 

less than 0.5 foot higher.

Table 3 was compiled from these records to show the occurrence, by 

months, of the low tides which reached or exceeded mean low water, 

which was 2.1 feet below mean sea level at Philadelphia, Pa. Mean 

low water is the average elevation of the daily low tides for a period 

of record. At Philadelphia, Pa., it is based on 19 years of record,
E14 HYDROLOGY OF TIDAL STREAMS

1940-58, as furnished by the U.S. Department of Commerce, Coast 

and Geodetic Survey. In explanation of table 3, it was found that a 

low low tide at elevations 6.6-7.0 feet (class range) had occurred 

three times during January for the period 1932-62. Thus, on the 

average, a low lo\v 'tide of 6.6-7.0 feet below mean sea level occurred 

about once in every 10 years in January. Similarly, by adding the 

total number of days having low tides in class ranges 4.1-4.5 and those 

farther below mean sea level for March, it was found that there were 

30 days during 1932-62 when the low tide was lower than 4.1 feet 

below mean sea level, or about once every year in March.

-6

-10

X fv1ean low water

1.01 1.1 1.31.5 2 3 4 6 8 10 20 30 

RECURRENCE INTERVAL, IN YEARS

50 100 200

FIGURE 6. Minimum low tide frequency curve for Delaware River at Philadelphia, Pa.

TABLE 3. Total number of days in each month for period 1982-62, when low low 

tide reached indicated elevation on Delaware River at Chestnut Street pier, 

Philadelphia, Pa.

Feet below 

mean sea 

level

2.1-2.5. _______

2.6-3.0. _______

3.1-3.5-_._____

3.6^.0------.

4.1-4.5-----__

4.6-5.0- ------

5.1-5.5-. --.___

5.6-6.0------

6.1-6.5.. 

6.6-7.0- -------

7.1-7.5-. 

7.6-8.0------

8.1-8.5-.- __._

Jan.

214

200

133

95

33

10

2

2

1

3

Feb.

195

60

30

13

7

1

March

230

161

75

38

14

3

April

9<_ .

1 CQ

CO

1C

May

271

43

2

June

<_ .9

1 4<_

July

QQQ

207

16

Aug.

328

167

29

Sept.

298

137

32

Oct.

269

149

55

13

Nov.

231

167

69

11

3

Dec.

188

2.7

140

78

44

13

2

1

1
RECORD LOW TIDE ON DELAWARE RIVEIR E15

The tabulation by months in table 3 disclosed some interesting facts 

relative to the occurrence of the abnormal low tides each month. For 

example, the lowest tides, 5.6 feet below mean sea level or lower, have 

occurred during the winter months. The occurrence of the lowest 

tides in winter may be due to the prevailing direction of the wind, 

which is from the northwest; tide levels at this time in the Atlantic 

Ocean in this vicinity are usually about 0.6 foot lower than in the 

summer, because of the changing declination of the moon. Also, 

because the prevailing direction of the wind during the summer months 

is from the southwest or in the upstream direction relative to the 

middle and upper reaches of the Delaware estuary, tides may be higher 

than in winter in part, at least, from this cause. In any event, it can 

be seen by table 3 that the low tides which have occurred during the 

summer months have not been significantly below mean sea level.

EFFECT OF THE RECORD LOW TIDE ON WATER QUALITY

Figure 7 shows daily maximum chloride concentrations during 

December 1962 and January 1963 that were recorded at three waterquality monitoring stations in the lower estuary. Concentrations were 

slightly higher than normal during December, a condition attributable 

to below normal fresh-water flow. Daily maximum chloride concentrations occurring at or near high-water slack ranged from approximately 3,000 to 5,000 parts per million at Reedy Island Jetty, and from 

200 to 1,200 ppm at the Delaware Memorial Bridge from December 

1 to 30.

On December 31, the salinity was affected markedly by the record 

low tide. The daily maximum chloride concentration at Reedy Island 

Jetty decreased from 4,080 ppm on December 30 to 1,770 ppm on 

December 31. The decrease noted at the Delaware Memorial Bridge 

station was from 780 to 110 ppm. This significant decrease in salinity 

was caused by the huge downstream flow of fresh water driven by the 

strong, sustained wind. On January 1, 1963, as the tides returned to 

normal, the quantity of fresh water flowing into the estuary was not 

sufficient to replace that which was lost into the bay and the ocean 

during the previous day. As a result, the fresh water was replaced 

by a surge of highly saline water from the Delaware Bay and the 

Atlantic Ocean.

Daily maximum chloride concentrations at Reedy Island Jetty, 

which is 5.7 miles above Delaware Bay, increased to 8,510 ppm on 

January 2, and remained well above 7,000 ppm until January 13. In 

comparison, ocean water contains about 19,000 ppm chloride. Concentrations of chloride on January 2 and 3 at the Reedy Island Jetty 

were the highest recorded since the station was installed in June 1956.
E16 HYDROLOGY OF TIDAL STREAMS 

9000

8000 -

7000 -

6000 -

5000 -

4000

2000 -

1000 -

3000 -

1 10 20 

December 1962

10 20 

January 1963

31

FIGURE 7. Daily maximum chloride concentrations of Delaware River at Reedy Island 

Jetty, Del., Delaware Memorial Bridge, Del., and Chester, Pa., December 1962 and 

January 1963.

The record at this station includes the 6-month 1957 salinity invasion 

which was generally considered the most prolonged and severe since 

1907 when the keeping of salinity records began. Fifteen miles upstream from Reedy Island Jetty at the Delaware Memorial Bridge, 

daily maximum chloride concentrations increased to a high of 3,800 

ppm on January 5 and 9. Daily maximum concentrations remained 

above 3,000 ppm until January 13. At the Chester station, which is 

13.5 miles above the bridge, daily maximum concentrations increased 

to 684 ppm on January 9, and remained greater than 50 ppm until 

January 22. Water in the Delaware estuary having a chloride concentration in excess of 50 ppm is generally considered to contain ocean 

salts.

The maximum penetration of ocean salts during this period was to 

a point near the mouth of the Schuylkill JRiver in Philadelphia. Water
RECORD LOW TIDE 03ST DELAWARE RIVER E17

analyzed at pier 11 North, which is about 8 miles above the mouth of 

the Schuylkill Eiver, did not show any ocean salts. Even though the 

chloride concentrations recorded from the Delaware Memorial Bridge 

upstream to Philadelphia did not establish new maximums of record, 

concentrations were abnormally high for the time of year. Also, the 

significance of the event is apparent if the magnitude of the concentrations and the relatively short duration of the invasion are 

considered. During a 2- 'or 3-day period saline water advanced 

upstream approximately 15 miles from the Marcus Hook area 

(immediately below Chester) to Philadelphia.

The hardships and hazards caused by the low water levels on navigation and waterfront industries were mentioned briefly earlier. The 

sudden increase in salinity which followed the record low tide also 

caused concern to many industrial users since the water's usefulness is 

directly related to its salt content. High salt concentrations are objectionable mainly because of increased corrosion and scale formation. 

Tolerances for industrial use vary, but 200 ppm chloride in water has 

been suggested as the upper limit of tolerance for many purposes. 

Where concentrations exceed this level, many users are forced to look 

for a more costly but less objectionable supply of water.

The effects of the abnormally low tides on the dissolved-oxygen content of the estuary were less pronounced. Figure 8 contains graphs of 

daily minimum dissolved-oxygen concentrations at pier 11 North 

(Benjamin Franklin Bridge station) and at the Chester station during 

December 1962 and January 1963. These stations were not completely 

operative on December 31 and January 1 and 2 because the water surface had dropped below the instrument intakes. The available data, 

however, still indicated the changes which occurred. Generally, dissolved-oxygen concentrations in the estuarine water are progressively 

greater above Philadelphia. During this period of prolonged ebb 

currents, more dissolved oxygen was flushed downstream into the 

Philadelphia and Chester areas. Concentrations at Chester during the 

first week in January were considerably higher than before the low 

tides. A slight increase in dissolved oxygen was also apparent at the 

pier 11 station. As the tides returned to normal, dissolved-oxygen 

concentrations reverted to their previous levels. Lower than normal 

low tides on January 24 and 28 produced similar but less significant 

changes in dissolved oxygen.

Slight changes in water temperature occurred as the river fell to a 

record low. The temperature of the water in the lower reaches of the 

estuary was 2° or 3°F cooler than that recorded at the stations before 

the record low tide owing to the cold snap of December 30 and 31.
E18 HYDROLOGY OF TIDAL STREAMS 

10

a. 7

Pier 11 North

Chester/

1 10 20

December 1962

10 20 

January 1963

31

FIGURE 8. Daily minimum dissolved-oxygen concentrations of the Delaware River at pier 

11 North, Philadelphia and Chester, Pa., December 1962 and January 1963.

SUMMARY AND CONCLUSIONS

The low tide of December 31, 1962, was a momentous natural phenomenon. The ususual magnitude of this event and its effects on the 

estuarine water and its users were noteworthy. At Philadelphia, Pa., 

this low tide was 8.5 feet below mean sea level, which was 1.7 feet lower 

than any previous minimum low tide since 1899. Most of the elevations for the December 31 low tide from just below Trenton, N.J., to 

Reedy Point, Del., varied from 8.5 to 9.6 feet below mean sea level. 

The greatest drop was in a reach above the Burlington-Bristol Bridge, 

where the water level of the low tide on the Pennsylvania shore was 11 

feet below mean sea level, about 2 feet lower than that on the opposite 

New Jersey bank.

No records of the low tide were available at locations along most of 

the Delaware Bay; however, the low tide elevation of 8.6 feet at 

Reedy Point, Del., and 4.5 feet at Breakwater Harbor, Del., gives an
RECORD LOW TIDE ON DELAWARE RIVER E19

approximate profile of low tide in the Delaware Bay. The low tide 

elevation that occurred at Breakwater Harbor was not record low, as 

slightly lower tides have been recorded during 5 years of an intermittent record since 1919. Also, the elevation of the low tide at Atlantic 

City, N. J., was 4.6 feet, which was 0.8 foot higher than the record low 

in March 1932. Thus, new records were set only in the Delaware River 

estuary, not in the lower Delaware Bay or in the Atlantic Ocean near 

the mouth of the bay.

Wind speed, duration, and direction were evidently the dominant 

causes of this abnormally low tide in the estuary. Variable and 

irregular profiles of low tide were caused by the fluctuating intensity, 

duration, and angle of the wind over the estuary. The cause of the 

extremely low tides, however, appears to be a strong wind from the 

northwest which lasted for a period of 30 hours or more. The direction of reach from just below Wilmington, Del., to the sea is in this 

general direction. Such a wind thus tends to sweep a huge volume of 

water out of the reach and to the sea, and the intensity and duration 

of the wind was found to be related to the abnormality of the low tide.

In addition to the valuable comparison that was afforded by the 

long-time record at Philadelphia, Pa., a study of the occurrence of 

abnormally low low tides during the period 1932-62 showed that the 

extreme low tides, 5.6 feet below mean sea level or lower, have occurred 

during the winter months.

A significant decrease in salinity occurred when the wind caused a 

large volume of fresher water from upstream to flow out of the estuary. 

With the return to normal tide levels, a severe invasion of saline water 

followed as sea water rushed in to replace the depleted fresh-water 

volume. The dissolved-oxygen content was also affected but to a 

considerably smaller extent.

SELECTED REFERENCES

Cohen, Bernard, and McCarthy, L. T., Jr., 1962, Salinity of the Delaware estuary :

U.S. Geol. 'Survey Water-Supply Paper 1586-B, 47 p. 

Durfor, C. N., and Keighton, W. B., 1954, Chemical characteristics of Delaware

River water, Trenton, New Jersey to Marcus Hook, Pennsylvania: U.S.

Geol. Survey Water-iSupply Paper 1262,173 p. 

Keighton, W. B., 1966, Fresh-water discharge-salinity relations in the tidal

Delaware River: U.S. Geol. Survey Water-Supply Paper 1586-G (in press). 

Mason, W. D., and Pietsch, W. H., 1940, Salinity movement and its causes in the

Delaware estuary: Am. Geophys. Union Trans., v. 21, pt. 2, p. 457-463. 

Miller, E. G., 1962, Observations of tidal flow in the Delaware River: U.S.

Geol. Survey Water-supply Paper 15S6-C, 26 -p. 

Pritehard, D. W., 1954, A study of flushing in the Delaware model: Johns

HopkinsUniv., The Chesapeake Bay Inst, Tech. Rept. 7.
E20 HYDROLOGY OF TIDAL STREAMS

Thomann, R. V., and Sobel, M. J., 1964, Estuarine water quality management and

forecasting: Am. Soc. Civil Engineers Proc., Sanitary Eng. Div. Jour., v.

90, no. SA 5, pt. 1. p. 9-36. 

Thomas, D. M., and Edelen, G. W., Jr., 1962, Tidal floods, Atlantic City and

vicinity, New Jersey : U.S. Geol. Survey Atlas HA-65. 

Zeskind, L. M., and Le Lacheur, E. A., 1926, Tides and currents in the Delaware

Bay and River: U.S. Dept. Commerce Spec. Pub. 123.

o