Purity of Water
Hydrographical Survey of the
Schuylkill River

Two excerpts from the Annual Report of the
Chief Engineer of the Water Department of the City of Philadelphia,
Henry P. M. Birkinbine,
presented to Councils Jan. 31, 1867.
Pages 60-67

The History of Philadelphia's Watersheds and Sewers

Compiled by Adam Levine
Historical Consultant
Philadelphia Water Department
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Before, however, any further extensions are made to the Works located on the Schuylkill, the importance of maintaining the purity of the water, should receive your attention. Within no equal period of time, has the amount of impurities drained into the Schuylkill increased to such an alarming extent as during the past year. This has been the result of the stimulation of manufactures, and the erecting of a number of new works in Manayunk and vicinity; such as paper-mills, oil refineries, &c.;

all discharging their refuse into the dam, from which the water supplied to the City is taken. The discoloration occasioned by these impurities is plainly discernible as far as the Falls, and sometimes at Columbia Bridge. [PAGE 61] This subject has so often been urged upon your consideration, that it is scarcely necessary to add anything to the many facts communicated in my former Reports. Yet that it is one of vital importance, is evident from the following, among other facts that might be adduced: "When the cholera visited London, in 1853, the parts of the city supplied with impure water suffered three and a half times as much as those supplied with better water; the deaths being 37 to 10,000 in the one case, and 130 to 10,000 in the other."

It was the intention of the Department to give you a detailed account of all impurities drained into the dam, and of the sources from which they come, but unforeseen circumstances prevented the procuring of the requisite data. Enough has been ascertained, in addition to what has been communicated in former Reports, to call for immediate action on the part of the City. It may be too late to prevent all this objectionable drainage, as a large amount of capital is invested in these manufactories, and a large and increasing population now inhabits the region drained immediately into the dam. Enough can be seen by the most casual observer, to satisfy him of these facts, When the river is not turbid, the water flows over Flat Rock Dam, and among the rocks, limpid, bright, and beautiful as a mountain stream; but follow it down a few hundred yards, and after passing the paper-mills, the river, for one half its width, is of a dark-brown color. Further down, it receives the refuse from dye-works and manufactories of every kind, the entire sewage of Manayunk, and the refuse from the Gas Works.

Below Manayunk, the river assumes a dark, dirty, milky appearance, and is covered with soiled waste and shreds from shoddy mills ; but by the time the water flows to the Falls, it assumes almost its original brilliancy ; here, again, it receives more objectionable matter from the chemical and dye-works, but at the Columbia Bridge it seems to have deposited or destroyed all objectionable matter; and at Fairmount has apparently regained its original [PAGE 62] purity. But there is no doubt that a constant deterioration in quality is going on, which, if not arrested, will ultimately force the City to abandon the Schuylkill as a source of supply, if the time to do so has not already arrived.

"The waters of rivers which traverse the grand centres of population become more impure in proportion to the developement [sic] of industry; for while the mass of the water remains the same, the causes of impurity become daily more abundant." So with the numerous creeks draining the undulating surface of our City, many of which, once bright and beautiful, are now befouled by refuse from manufacturing establishments, and are being covered out of sight, one after another, as objects too loathsome to look upon, whose fetid waters would spread disease and death, were they not thus hidden. Is there no remedy for this? Shall our industry only tend to make the most beautiful and necessary of objects loathsome, or shall we, by the strong arm of law, protect the purity of the water, and force manufacturers to find some other means of carrying away refuse matter?

The City has invested a large amount of money in the Works for pumping water from the Schuylkill, and the purity of the water supplied is a matter of great importance. If it is determined to continue this as a source, a large expenditure for the purpose of securing pure water, will be warranted.

If the drainage from factories and other sources could be prevented from flowing into the dam, the quality of the water would be unexceptionable, except in time of freshet, when, for a few days, the water is always turbid. This could be prevented by subsiding reservoirs of sufficient capacity. A city with the wealth and number of inhabitants of Philadelphia, should, at least, be able to supply itself with an abundance of pure water.

The project of purchasing the property on both sides of the lower part of the dam, and using it as a park, is a valuable suggestion, and worthy of your approval. It would do much to prevent [PAGE 63] objectionable drainage in the immediate vicinity of the Works; but this alone, will not insure the purity of the water; some disposition must be made of the objectionable drainage from above.


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The dam at Fairmount forms a subsiding reservoir, in which the water of the Schuylkill is allowed to partially purify itself before being pumped into the reservoir. It is, therefore, of the utmost importance that it should be kept as free as possible from shallow, stagnant pools. For the purpose of ascertaining the amount of mud deposited, and the general features of the river, a survey was made, in 1861, extending from Fairmount to Columbia Bridge, (see my Report for that year, pp 9-18.) Between these points, a large percentage of the matter held in suspension in the water is deposited, owing to the slow current; viz:—two miles per day.

This was compared with a partial survey made in 1852, under the direction of the Schuylkill Navigation Company, which showed that some portions of the river were rapidly filling up, and that great alterations in its general features were taking place.

In 1864, a second survey within the same limits was made and compared with that of 1861, when great changes in the shore and channel were found, (see my Report for that year, pp. 4-13)

These changes were great, and increased so visibly, that, in order to ascertain the physical laws controlling the deposits, a third survey was made, in November and December of the past year. It was more extensive and thorough than either of the others, embracing the river from the Wire Bridge, at Fairmount, to the Reading Railroad Bridge, at Schuylkill Falls. From it the accompanying map was made. This map is an exact plot of the river between these points, and exhibits the general topography of the shore and islands, the location of buildings near the river, the [PAGE 64] position of bridge-piers arid wharves, lines of soundings, etc., and the line of shore, in 1861. The principal boundaries are the Philadelphia and Reading, Pennsylvania Central, and Junction Railroads.

The transverse sections are taken at various points, A-A1, B-Bl, C-C1, &c., which best show the general prism of the river; and in those embraced in the other surveys, the variation is shown by dotted lines. Thirty-eight such transverse sections were taken, averaging 500 feet apart, and, on these, soundings were taken every twenty feet. The longitudinal section exhibits the deepest soundings on each of the thirty-eight lines, and is on a scale of 200 horizontal to 1 vertical.

The rapidity of these changes will appear from the following data. The amount of water contained in the river, between Fairmount Dam and the Columbia Bridge, and the amount of deposit, is as follows:

 cubic feet.
Contents of river, 186184,203,928
Contents of river, 186480,890,247
Contents of river, 186674,247,658
Deposit from 1861 to 18643,313,681
Deposit from 1864 to 18666,642,589
Deposit from 1861 to 18669,956,270
Daily average deposit5,430
The deposit may be locally divided, as follows: 
From Fairmount Works to line D-D1, at the Skating Club House2,221,356
From line D-D1 to line G-G15,856,858
From line G-G1 to line K-K1, at Columbia Bridge1,878,056

The mean daily average discharge of the river, exclusive of storm-water, is estimated to be 87,162,240 cubic feet. Accordingly, this reservoir is more than emptied each day. The contents of the river were equal in

1861, to the amount discharged in 23 hours, 11 minutes.
1864, to the amount discharged in 22 hours, 16 minutes.
1866, to the amount discharged in 20 hours, 26 minutes.

The general appearance of the river has changed considerably, as will be seen by following the dotted line which exhibits the shore line of 1861. Long Island, just below Columbia Bridge, has enlarged and changed its position somewhat. Briar Creek has made a bar at its mouth, and the bar opposite it, outside of the canal, is increasing. Below the rolling-mill, on the opposite side of the river, the shore has made out considerably into the stream. Under the eastern end of Girard Avenue Bridge, the shore is now nearly out to the end of the Schuylkill Water Works' wharf; and along the Park, the shore line has, in several places, encroached considerably upon the river. The most prominent of these encroachments is below Turtle Rock and the Skating Club House, where, for 800 feet, light batteaux cannot approach to within 100 feet of the original shore line. There is also a large deposit just above the steamboat wharf, at Fairmount.

The greatest and most prominent deposit in this portion of the river is, however, opposite the Twenty-fourth Ward Water Works, where an island 1100 feet long, and averaging 160 feet wide, has been formed. The tow path, between the points D1 and G1, is now useless, as even light-draught boats cannot, in some places, approach within 500 feet of it. Three-fifths of the whole deposit in the river, nearly 6,000,000 cubic feet, is contained in this island and in the encroachment of the shore between those points. These deposits have necessarily contracted the river, and reduced the superficial area about nine per cent.
[PAGE 66]

Superficial area,Square feet
in 18617,333,327
in 18647,032,123
in 18666,646,801
reduced from 1861 to 1864301,204
reduced from 1864 to 1866385,322
reduced from 1861 to 1866686,526 (or 15.76 acres)
Daily decrease of superficial area, 375 squ. ft.

The mean sectional area, or the prism of the river, is less than in 1861. The stream has increased in depth and decreased in breadth. The decrease of the sectional area and width, and the increase of depth, will demonstrate that, in time, a mere channel will take the place of the large subsiding reservoir which was formed by the construction of Fairmount Dam; and the water drawn into the pumps will have less opportunity to be at rest, and to deposit matter held in suspension.


Greatest breadth,1,105 ft.1,050 ft.1,010 ft.
Least breadth,420 ft.440 ft.450 ft.
Mean breadth,825 ft.732 ft.735 ft.
Greatest depth,35.2 ft.36.1 ft.37.5 ft.
Greatest average depth,18.8 ft.17.2 ft.20 ft.
Least average depth,7.6 ft.5.8 ft.3.9 ft.
Mean depth,11.3 ft.10 ft.11.5 ft.
Greatest sectional area,10,518 sq. ft.13,136 sq. ft.12,644 sq.ft.
Least sectional area,6,700 sq. ft.2,589 sq. ft.1,380 sq. ft.
Mean sectional area,8,254 sq ft.8,153 sq. ft.8,087 sq. ft.

No comparisons of contents, area, &c., can be made with that portion of the river between Columbia Bridge and the Reading Rail Road Bridge, as no survey was made of it, prior to 1866. [PAGE 67] The present survey will be a basis for future comparisons. Columbia Bridge is about midway between Fairmount Dam and the Reading Rail Road Bridge, being 8,750 feet from the former, and 8,420 feet from the latter. It may be interesting to compare these two portions of the stream.

 Below Columbia Bridge.Above Columbia Bridge.Total.
Cubical content,74,247,658 ft.54,347,703 ft.128,595,361 cu. ft.
Superficial area,6,646,801 ft. 6,004,828 ft.12,651,629 sq. ft.

Greatest sectional area,12,644 sq. ft.9,192 sq. ft. 
Least sectional area,1,380 sq. ft.3,192 sq. ft. 
Mean sectional area,8,087 sq. ft.6,157 sq. ft. 7,117 sq. ft.
Greatest breadth,1,010 ft.975 ft. 
Least breadth,450 ft.375 ft. 
Mean breadth,735 ft.658 ft. 697 ft.
Greatest depth,37.5 ft.25 ft. 
Greatest average depth, 20 ft.12.7 ft. 
Least average depth,3.9 ft.6.4 ft. 
Mean depth,11.5 ft.9.6 ft. 10.6 ft.

From these data it will be seen, that, while the superficial area of the portion above the Bridge is nearly as great as that below, yet the cubical contents are one third less. The breadth of the stream is more regular, and the mean depth less.

The above data will be of great service in any plan for main, tainting the purity of the water. The Department is not prepared to suggest a plan, as further investigations will be necessary.



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