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With ueption of the St. Lawrence, the busquehanna 

River basin is the largest and most Important on the Atlantic 
Coast, and embraces a total area of 27,1+00 sq» miles, which com- 
prises h7% of the total area of the State of Pennsylvania, ] 
of the total area of the State of Mew York, and 2.% of the total 
area of the State of ..aryland. 

The annual precipitation over this area, according to 
records of the United states Weather bureau, varies from 5I.I4. 
inches to I4.i1- J inches, with a mean of J9«U inches. The run off 
which eventually finds its way to the sea through the Susquehanna 
River, varies from 16. 6 Inches to 29. 1 inches and averages ^% of 
the rainfall. ±he run off is at a minimum in August, September, 
and October, during which months it ranges from ^ to $0% of the 
rainfall and averages about l%c Like all other Pennsylvania 
streams, the Susquehanna River has a natural run off extremely 
variable, both from day to day or week to week and from season to 

High waters frequently occurs in January from melted 
snow. Floods accompanied by ice gorges occur usually in : arch 
and result in a- high water level, although with lesser volume of 
flow than at times of clear water floods caused by heavy rainfalls, 
occurring over the whole or a port! on of the water shed as late as 
June. In late summer or fall, periods of low water are frequently 
not ed . 

During the past century there have been several great 


floods in this river, the most notable of which ".'as that of June 

~), which was coincident with, although not caused by the 
Johnstown Flood, and which probably exceeded any flood that ever 
occurred in this stream. It is estimated that during this flood 
the flow reached a maximum of 7^; , C cubic feet per second. 

'icial hydrograph of the ..usruehanna River for 
years 1691 to 19^5 shows that the minimum discharge at Larrisburg, 
Pa. was ^,aOC cubic feet per second, this occurred in 1909* 

The head waters of this river system are on the elevated 
plateau 'which separates the waters which flow south and east, into 
the Atlantic streams from those flowing north and west Into the 
ississippi, St. Lawrence and Great Lakes. 

The Susquehanna river has a fairly uniform grade of 2 
feet per mile throughout its entire upper region. Below, or ! 
the lov.-er forty miles of its course the slope increases to an 
average of ^ feet per mile to tidewater and the width of the river 
becomes contracted, narrt into a gorge, which in places is re- 

duced to a width of two-tenths to one-half mile. 

In the last ^7 "ilea of its run the river drops from an 
elevation of 225 fset with an average slope of 5.6 feet per mile, 
causing a swift current, which has worn a low water channel of 
great depth in many places. 

long this lower section the river has cut its way thro - 
a range of tableland and its bed is walled by steep rocky bluffs on 
both sides, affording excellent foundation for water power develop- 
ment • 

For more than forty years the possibilities of power de- 


velopment In this lower course of the Susquehanna River have en- 
gaged the attention of engineers and capitalists. The first 
evidence of contemplated power development In this river is found 
In the act of Legislature of the state of Maryland which was 
passed in Ibbij. authorizing the busquehanaa Water Power and Paper 
Company of Harford County to acquire certain property, hy condem- 
nation, necessary for the proper extension and development of its 
existing dam or any dam it might locate or build near that site. 

This water development consisted of a small wing dam in 
the bed of the river an Intake channel, head gate, power plant and 
tail race. Part of this work is still in existence and comprises 
what might be termed the first water power development of the 
Susquehanna River. 

Until, however, the growth of the steam generated elec- 
tric systems In nearby cities had developed a market capable of 
absorbing a large part of the energy in the flow of this river Its 
power development was not economically feasible. 

However, in 19 10 the Pennsylvania Water and Power Com- 
pany completed a dam and power house at Holtwood, Pennsylvania, 
which now has an lied horse power. 

The . .lecvrlc j t %t 'c . its subsid- 

iary, Philadelphia Electric Power Company and the latter's .''ary- 
land subsidiary, The Susquehanna Power Company, obtained a Federal 
License, which was approved February 20, 1926, to build a da^ and 
power house at ConoYvingo, ,.d. 

The dam and power house will be located in Maryland, but 


the upper half of the reservoir and the greater portion of the 
transmission lines will he in Pennsylvania. This required joint 
action by the Public Service Commissions of the two states. i lso, 
as the sr Department has ruled that the busquehanna is a navi- 
gable river, a license from the Federal Power Commission was re- 

The reason for the dam being in Maryland was to be able 
to produce the required maximum head. 

By agreement with the Pennsylvania Water and Power Com- 
pany, a pool elevation for the Conowingo Dam of 10b. 5 feet above 
mean sea level, has been adopted. At this, elevation the i^ater 
will be backed up over a portion of the Holtwood riant ' s tail 
race, which has not yet been excavated but which when excavated, 
.will result in development of increased head and power at the 
Holtwood Plant. It was mutually agreed that this addtional head 
could be developed more economically at Conowingo, and it there- 
fore has been arranged, subject to approval by commissions having 
jurisdiction, that the Cpnowingo pool be maintained at elevation 
IO8.5, the holtwood Company to share in Conowingo' s Plant's gain 
accruing from the increased head. 

ith the pool elevation decided upon, it was desirable, 
in order to develop the maximum head, to locate the dam as close 
to tidewater as possible. Here, the Columbia and Port Deposit 
Branch of the Pennsylvania Railroad Company, located on the east 
bank of the river., imposed a limitation, In that it was necessary 


to provide a satisfactory grade from the present road "bed to the 
north end of Port Deposit to the elevation of the relocated 
tracks above the Coiowingo Dam. A grade of •J5/& was finally 
accepted by the Railroad Company. 

Five possible sites for the conowlngo Dam were examined 
and an exhaustive study made of the head and power available and 
the total cost of development at each. The site as finally 
adopted is located approximately two miles belcw the village of 
Conowingo, Maryland, and is far enough north of Port Deposit to 
permit the use of the accepted maximum run off grade of the rail- 
road. A reservoir having an area of approximately llj. square miles 
will be formed. 

The hills on either side of the river at this location 
form natural abutments, that on the Cecil County or east side 
rising to an elevation of 250 feet above sea level, and on the 
Harford County or west side rising to an elevation of 155 feet. 

The river bed and banks to a height well above the pond 
level, are of granitic formation. During the Autumn of 192^ twen- 
ty six core borings were made along the line of the up- stream face 
of the dam, between the two abutments. These were drilled to 
depths varying from 5 feet to JO feet below the rock ledge. All 
these cores showed firm hard granite or gabbro. In additional to 
these, four borings were made to a depth of 100 feet below the 
rock ledge, and these also showed hard rock for their entire 


Qn the east bank then Is ample space for the erection of 
construction carp and plant and for storage of materials* Trans- 
portation facilities are supplied by the Columbia and Port Deposit 

The main channel of the river at this site is along the 
west bank. The power house therefore is being built at this end 
of the dam. Space for construction plant on 'this side of the river 
is somewhat limited, but an old canal which formerly operated on 
this bank has been partially filled in to provide space. To sup- 
ply transportation facilities for the power house construction It 
was necessary to construct approximately 10 miles of railroad to 
connect with the Pennsylvania Railroad System at Havre de Grace. 
The tow path of the old i'idewater Canal afforded an excellent road 
bed, requiring very little grading, and within three months of 
the start of construction work this railroad was in operation. 

Early In March, 19^6 the construction of the Conowingo 
Dam and Power House was started, with an initial wheel capacity of 
•57&,000 h. p. (;?9lj.,000 h. p. nit I -ate capacity). As the Phila- 
delphia Electric Company will use practically the entire output 
of the Conowingo Project, It was necessary that it should control 
the operation of the plant- It was also essential, In order to 
make the securities of the project attractive to the investing 
public, that the Philadelphia Electric Company should guarantee 
the completion of the project and be responsible for the payment 
upon which the securities of the project depend for support. As 


the Philadelphia Electric Company is not allowed by its charter 
to do business in Maryland, these requirements were met by ar- 
ranging to have three subsidiary corporations as follows: 
First, the Susquehanna Power Company, incorporated in Maryland, 
will own all physical property of the project located in that 
state, comprising the dam, power honse and tail race, and portions 
of the reservoir and transmission lines. 

becond, the Philadelphia Electric Power Company, incorporated in 
Pennsylvania, will own all physical property located in Pennsyl- 
vania, this being principally lands for the reservoir, and also 
the greater portion of the transmission lines. This company also 
owns all of the stock of the Susquehanna Power Company. 

The voting stock of Philadelphia Electric Power Company 
is all owned by the Philadelphia Electric Company, which also 
leases the transmission lines owned by Philadelphia Electric 

And third, the Susquehanna Electric Company which was formed for 
the purpose of leasing for the term of license, the properties of 
The Susquehanna Power Company in Maryland, under contract with 
the Philadelphia Electric Company, will operate the plant and 
will sell all energy generated to Ihe Philadelphia Electric Com- 
pany. All stock of The Susquehanna Electric Company is owned by 
The Philadelphia Electric Company. 

As set up, therefore, the Conowingo Hydro Electric 
Development is being made by and for The Philadelphia Electric 
Company and when completed, will be operated as a part of that 
Company's system. Th construction of the development is in 

charge of the Engineering Department of The Philadelphia Electric 

Contract for the design and construction of the dam and 
and power house has been awarded to Stone & Webster, inc., who 
have subcontracted the construction of the greater portion of the 
dan to The Arundel Corporation of Baltimore. The Arundel Corpora- 
tion has been awarded also the contract for relocation of the 
tracks of the Columbia&Port Deposit Branch of the Pennsylvania 
Railroad. Contract for the design and construction of the trans- 
mission lines, and for t itching station located on roof of 
the power house has been awarded to Day & Zimmermann, Inc. 

The west abutment of the dam is in a projecting hill or 
rock, into which a retaining wall section, extending IJ4.5 feet from 
the power house to the abutment, will be built to for'- an adequate 
seal for the impounded waters. The head works for the power house 
providing for eleven main units and two station service units, 
then extend 900 feet to the beginning of the spillway section which 
is ^56^ feet long. Prom the east end of the spillway the retain- 
ing wall section continues 1^00 feet to the east abutment, which 
also serves as the abutment for the highway bridge over the re- 
located tracks of the Columbia and Port Deposit Railroad. 

The dam. is solid nasonry construction of gravity type, 
founded on rock at an average elevation fifteen feet above sea 
level. The spillway section is designed to take care of floods 
up to 860,000 cubic feet per second. It has fifty movable crest 
gates for the purpose of regulating the level of the storage 

. ■ . 

reservoir. They are &>\ feet high by I4O feet long and weigh 
about I4.2 tons eac. . 

The , , is located adjacent to 

the west shore. The head works provide intakes for the eleven 
main units and two service units. By locating the top of the i - 

e openings l f feet below the pool level, protection from float- 
ing ice has been secured without expense of constructing the usual 
rock fill nnd skimmer arch to protect the forebay. 

The superstructure of the power house will be concrete, 
with a structural steel frame* The high-tension switching station 
will be located on the roof. 

Seven main water wheel units will be Installed at this 
time, fair will come from the Allis-Chal tiers Manufacturing Company 
three from the . Crao ons Ship ngine Building. Company . 

Each unit will have a capacity of $l[ t 000 h. p., and will be the 
vertical shaft, single runner, cis reactic e. 

The two station service water wheel units, supplied by 
the S. organ S lith Company, will be 1900 h. p. each and of the 
same type as the main water ''heel units. 

Seven main generators and two station service generators 
i.l be Installed; four main generators to be provided b; Gen- 

eral Electric Company and three main generators and the station 
service generators by the westinghouse Electric and Manufacturing 
pa ny * 

Each main generator will have a capacity of 1+0, CT(" ' va., 
generating at I3.&OO volts, J phase, 60 cycle, will be direct con- 


nected to a main water wheel unit and I LI be provided with direct 
connected 71> kva. auxiliary a.c. generator. 

Each station service generator will have a capacity of 
lbOO kva., generating at I4.6O volts, 5 phase, 60 cycles, will be 
direct connected to one of the station service water wheel units, 
and will be provided with a direct connected d.c. exciter. 

Stationary power transformers will consist of four 
of three transformers each having the following rating: 26,667 kva., 
rated capacity, 29,553 kva., overload rating, single phase, water 
cooled, 15,b00 low tension voltage and 127,000-222,000 volts Y at 
the high voltage terminals. The guaranteed efficiency at rated 
capacity is in c- 

The li - plant will be transmitted 

to 3elphla at 220,' 0< volts to be utilized in The Philadel- 

phia Electri c Coi 

expected that the seven units 
of the initial Installation will generate 1,580,000,000 kilowatt 
hours . 

sn the Pennsylvania Railroad is electrified between 
Philadelphia and .'ashington, they will receive all of their 
from the Plant at Gonowingo. 


Current News, Philadelphia Electric Go. 

Records, 0.3. Wenther Bureau 

Weatinghouse International 

Public Ledger Philadelphia 

nlex«nder Villi son 3rd. Const rut ion Engineer of the Philadelphia 

Electric Co. 
V. H. Jones Philadelphia Electric Co. 

Present Progress on the 
$52,500,000 Conowingo 

Power Project as 
Viewed From the Air 

In the foreground is the construction city, which has sprung up like a mushroom since the start of the work 
ago. The huge power plant will rise in the triangle at the western end of the dam. The cleared track ex' 
picture is the route of the sixty-five-mile transmission line to Philadelphia. The winding white road is the I 
run over the completed dam, shortening the auto route to Washington by four and a half miles. The white 1 
marks the. relocation of the Columbia and Port Deposit Railway, which is being moved back for a di 


Paper Mill Island, 
just above the darn, 
will be entirely sub- 
merged. Across the 
narrows is the Cono- 
wingo Bridge, which 
will be abandoned 
when the Baltimore 
Pike is carried over 
the t we n t y - foot 
roadway atop the 
dam. The work will 
be inspected next 
Friday by the Gov- 
ernors of Pennsyl- 
vania and Maryland 
and a distinguished 

Photos (c) Victor Damn 

Captain Lindbergh 
explaining the 
mechanism of his 
plane to King Albert 
at the Evere aero- 
drome, Brussels 
<c> p. 4 A. 

WF 7* 



A striking bust of 
+Urt Trf\n+-"hfnl air 


The dam is 4633 feet long, or 300 feet longer than the famous Wilsor^ 
ShoaLs. In the dis- ' ' 



The 9000-acre lake 
formed by the com- 
pletion of the dam 
late this summer 
will extend almost 
up to the Holtwood 
dam and power plant 
(shown in center of 
picture), which sup- 
ply Baltimore with 
power. The capacity 
of the basin will be 
14,000.000,000 gal- 

9— East Plant, general 

■ '^-wiL. 


■ ',£ 


view showing progress a} 
construction «« tiarn. 

Fig. 10 — /;as/ Plant, showing constmction-bridge, deck, gantry 
crane and concrete mixing plant. 




Montrose -'"") v — N 


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w .■ i NEWBUH6" 






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Harpers Ferry — y 



fj£. J. MfljJ SbowiiiR Susquehanna River Basin. 

A — West Plant — Looking upstream from towpath showing west abutment, west of first service unit, and retaining wail. B — 
West Plant — Looking north-northeast from west ahntment at night, showing work in power home cofferdam. C—East Plant — 
Looking south-southwest along downstream side of construction trestle during flood. Cofferdam under about 9 feet of water. D — 
West Plant — Looking north-northeast from west ahntment showing progress in power house cofferdam and concrete at xvest 
abutment. E — East Plant — Looking south from Petwa. Railroad showing progress on dam. Contraction joint of abutment sec- 
tion is at station 34 50* 

F — East Plant — Looking northeast from end of upstream cofferdam showing progress on spilhi'ay section, G — -East Plant — 
Looking w? at -north west from construction trestle showing water tunning through }%-foot opening in spillway section during flood. 
I! — East Plant — Looking north- northwest from construction trestle showing water running over cofferdam and through ? 9 -foot 
opening in spillway section. I — East Plant — Looking southwest from construction trestle shotting abutment section of dam raised 
to 1 12 J I feet. Four piers raised to final height y 108 J feet* One 4$" highway girder in place. Contraction joint is shown at 
station 54 FO* 


Fig. t, l-'iiitnl Stairs Gtohn'Ciil Survey Ms(i, \bowltif tbi territory in which the Ctujtowittgo Project is Inratt,!, iiiit iht 
rrlitttt'f position!, nf Holtwooil ana Cr»um-hig,o Diim. 

The frame of one of the Westinghouse waterwheel generators for the Conowingo development as It lay on the floor of the Weslinfthouse Works at East Pittsburgh, 

This frame Is 38 feet in diameter and it is not exceeded in size by any other machine except the large steam 

engine driven generators built by Westlnghouse two decades ago. 


One of the seven 
ft elf -cooled trans- 
formers built by 
WeKtin&house for the 
Plymouth Meeting 
Station of the Phlla- 
d e I p h J a Electric 
( ]o in pu ny ne:t r P h il- 
-i d *• I \* h i -i IT. S. A. 
These t ransf or m ers. 
tire the largest tilnftle- 
phase transformers 
in the world. They 
are rated at ££ T 333 


-I I I !?■■> '**■ 


'■ : 'r, ; ^ 

l : i%. 4— Showing general plan ami sections of dam. 

Cors + rvc-fsos? Ca mfe on 
\fces f ^honk. 



Yr r 

■; ->»•,: 

C rune. \t$o,d ~t* ra/fc 

/^we/ /-/a use- &r><sf 

Vie yV O / Dam 'from 
W&J^ Bank