Engineer-in-Charge 1886

From the 1886 Annual Report of the Philadelphia Water Department


Other documents related to this report include:
Sanitary Survey of the Schuylkill River from 1883-1884, which can be found here.
A preliminary 1884 report by Rudolph Hering, which can be found here.

OCR Text conversion by Annie Cheng, PWD Archives Intern 2003-2004.

All tables and other graphics originally scanned at 300 DPI using a disbound copy of the 1886 report
in the PWD Historical Collection. Not all tables and graphics are included.

Numbers in the image filenames refer to the report page number on which that image originally appeared.

The History of Philadelphia's Watersheds and Sewers

Compiled by Adam Levine
Historical Consultant
Philadelphia Water Department
HomeCreek to sewerDown underarchivesmapsAdam LevineLinks

The 1886 annual report of the Philadelphia Water Department contains scores of tables, diagrams, maps and photographs. Many of these concern the search for a new water supply. The city undertook such searches periodically, starting after the Civil War and continuing into the 1940s. The original public water sources for the City, the Schuylkill and Delaware rivers, were never abandoned no matter how badly polluted they became, but over the years many proposals were put forth to bring water into the city from cleaner sources north of Philadelphia.

Rudolph Hering's 1886 proposal is one of the most comprehensive of these water supply plans, and certainly the best documented. Besides the material included here, Hering made preliminary reports on his work in the 1883, 1884 and 1885 annual reports. The PWD Historical Collection has a series of large-scale detailed maps created to illustrate the various proposals in Hering's report.

Although none of Hering's recommendations were ever implemented, his report and the accompanying documents exemplify the tremendous amount of research needed even to produce a proposal of this sort. Most of the groundwork was accomplished literally on the ground, by surveyors who measured and mapped the land, by gauges that monitored stream flow and rainfall, and by sanitary engineers documenting sources of pollution in each watershed. Besides this engineering record, the report provides valuable historical information about several large watersheds, which might be compared with current stream flow and water quality data to get a sense of the degradation of these water sources over time.

[PAGE 257]


JOHN L. OGDEN, Esq., Chief Engineer.

SIR:--Herewith is submitted the following report of progress during the year 1886, of the Hydrographic work in connection with the investigations of sources for a future water supply. The following streams have been gauged throughout the entire year, viz.: The Perkiomen creek, at Frederick Station on the Perkiomen Railroad; the Neshaminy Creek, a short distance below the forks formed by the meeting of the Big and Little Neshaminy creeks; and the Tohickon creek, about one-half of a mile above its mouth at Point Pleasant.

During the year rainfall observations have been taken at ten stations, established by the Department, namely:

Office of the Water Department, Philadelphia, Pa.
Germantown, Philadelphia, Pa.
Siesholtzville, Berks County, Pa.
Frederick, Montgomery County, Pa.
Ottsville, Bucks County, Pa.
Quakertown, Bucks County, Pa.
Smith's Corner, Bucks County, Pa.
Point Pleasant, Bucks County, Pa.
Forks of Neshaminy, Bucks County, Pa.
Lansdale, Montgomery County, Pa.

[PAGE 258] The Department has also received annual rainfall reports from the following places:

United States Signal Service Station, Philadelphia., Pa.
Pennsylvania Hospital, Philadelphia, Pa.
Lebanon, Lebanon County, Pa.
Schuylkill Haven, Schuylkill County, Pa.
Reading, Berks County, Pa.
Pottstown, Montgomery County, Pa.
Browers, Montgomery County, Pa. Easton, Northampton County, Pa.
Phillipsburg, Warren County, N. J.
Princeton, Mercer County, N. J.
Fallsington, Bucks County, Pa.
Moorestown, Burlington County, N. J.
West Chester, Chester County, Pa.

A new pine crest was placed on the Tohickon weir in July, the old crest having been carried away by the ice during the previous winter.

As it was necessary to have measurements of high flows on the Tohickon, to refer to gauge readings taken at the new automatic stream gauge, and as the channel under the road bridge at Point Pleasant had changed, so that correct measurements could no longer be obtained at that point, other means of measuring the high flows had to be found. About 150 feet above the Tohickon weir a one-quarter inch galvanized wire cable ,vas stretched from shore to shore, high enough to clear the flows intended to be measured. The ends were securely anchored to trees, a pulley block with tackle attached was placed on the cable, and a small boat attached to the tackle. Guy ropes were fastened to either shore and placed in the boat. As the velocity of the water at this point is very great, sometimes reaching twelve to fourteen feet per second, it was necessary to have everything very secure. With this apparatus, persons in the boat engaged in taking measurements could place themselves at any point in the stream, from one shore to the other, and from the weir to a point 150 feet above [PAGE 259] it. Sections were carefully taken with a level at two stations, as it seemed probable that under certain conditions it would be advisable to make the measurement at one station, while under different conditions it would be better to use the other. Current meters and floats have been used to determine the velocity {)f the water. The surface slope of the water between stations 7.5 feet apart was obtained at each measurement, and the measurement checked by calculating the flow from the section of the stream and the surface slope, as applied in Kutter's formula. It is surprising how closely the results agreed, considering the extremely rough character of the bed of the stream. Five measurements of high flows were made on the Tohickon during the year, three of which gave good results, One only fair, and one unsatisfactory.

Three stream gauges were replaced by new ones during the year.

The rainfall for the year is generally somewhat above the average, although in a few localities it does not differ from the average to any great amount. At the Pennsylvania Hospital, Philadelphia, the average annual rainfall for the past sixty-two years, including the year 1886, is 44.452 inches, while the rainfall for the year 1886 is 47.060 inches. There were only two storms during the year that can be called heavy. The first occurred on February 11, and amounted to about 2.6 inches; the second occurred on May 8th, and amounted to 3.5 inches nearly. The storm of February 11 caused unusually high water in all the streams, the water reaching a greater height than it had attained since the year 1869. A report of the damage sustained by the hydrographic work from this storm will be found on pages 376 and 377 of the Annual Report for 1885.

Table 1, following this report, contains a comparison for the past year, of the rainfall at twenty-two stations in the Delaware and Schuylkill watersheds, with the rainfall at the United States Signal Service Station at Philadelphia.

[PAGE 260] Table 2 gives the details of the storms of greatest intensity occurring during the year 1886.

In Table 3, containing a comparison of the rainfall with the stream flow in the three watersheds under investigation, it will be noticed that the year is begun on October 1st instead of January 1st. The reasons for so doing are; first, the minimum stream flow occurs about October 1st each year, but the maximum flow cannot be said to occur at any well defined date, varying in different years from about the 1st of January to the latter part of March; and second, rains occurring about January 1st almost invariably raise the streams and change decidedly the total for the year; but rains occurring about October 1st, unless of considerable magnitude, have very little effect, upon the streams. As it is advisable to begin the year at a time when the stream flow possesses the same general character each year, the 1st of October has been selected. The yield of the various streams for the past year is somewhat above the average annual yield.

By an inspection of the column, giving the percentage of rainfall reaching the stream in Table 3, it will be seen that the Perkiomen percentages are less in the winter and greater in the summer months than the percentages of the other streams. The character of the Perkiomen watershed fully explains this greater steadiness of flow, being more heavily wooded in proportion to its area than either of the other watersheds, and having its most heavily wooded areas about the sources of the stream. Although the Tohickon watershed is considerably smaller than that of the Neshaminy below the Forks, yet the stream flow for the past year is about the same in each. This can be accounted for by several facts. The percentage of rainfall reaching the stream has always been considerably larger in the Tohickon watershed than in the Neshaminy. In the year 1885, the Neshaminy and the Tohickon gave very nearly the same stream flow, although that of the Tohickon was slightly less. During the past year the rainfall in the Tohickon watershed [PAGE 261] was slightly greater than that in the Neshaminy, although the difference is not sufficient in itself to account for the increased stream flow in the former. All the freshets occurred from January 5th to May 9th, during the winter and spring months, at a time when the Tohickon watershed gives off a much larger percentage of rainfall into the stream than either of the other watersheds.

Table 4 contains the average annual stream flow in the various watersheds under investigation, compared with the average annual stream flow in the Sudbury and Croton watersheds. In the last column will be found the stream flow reduced to cubic feet per second per square mile of watershed, but by glancing at the column containing the rainfall, it will be seen that the rainfall varies in the different watersheds; and therefore, to compare the stream flow as given in the last column of the table, it will be necessary to still further reduce it to a common basis of rainfall. I have taken each quantity in the last column, and divided it by its respective annual rainfall, and have obtained the following quantities, each being the stream flow in the respective watersheds in cubic feet per second per square mile of drainage area; for each inch of rainfall:

Perkiomen, at Frederick........0.041
Neshaminy, below Forks......0.038

Table 5 contains the monthly stream flow for the year 1886.

Both the Delaware and Lehigh rivers reached a lower point during 1886 than they have since the Department began to gauge them. Unfortunately, through lack of funds, no measurements could be taken during the period of low flow at White Haven, Delaware Water Gap, and Point Pleasant.

[PAGE 262]

The following persons have been engaged on the work during the entire year:

John G. Hilsman, rodman.
George W. Wood, rodman.
R. C. Stover, gauge observer.
E. F. Heavener, gauge observer.
George Lowder, gauge observer.
Dr. J. A. Roth, gauge observer.
H. L. Shull, gauge observer.

The Department is indebted to the following persons who have kindly furnished rainfall records:

Mr. Thomas Meehan; Germantown; Pa.
Mr. J. L. Heacock, Quakertown, Pa.
Sergeant L. M. Dey, U. S. Signal Service, Philadelphia.
Mr. E. F. Smith, Chief Engineer of Canals, Reading, Pa.
Mr. Benjamin Shoemaker, Pennsylvania Hospital, Philadelphia, Pa.
Mr. Thomas J. Beans, Moorestown, N. J.
Dr. Charles Moore, Pottstown, Pa.
Mr. B. B. Lehman, Lebanon, Pa.
Mr. Milnor Gillingham, Fallsington, Pa.
Mr. Malcolm McNeill, Princeton, N. J.
Miss Emily Kent, Phillipsburg, N. J.
Prof. James W. Moore, M. D., Easton, Pa.
Dr. J. C. Green, Westchester, Pa.

The three automatic stream gauges in use are all in good condition, and a new gauge that has never been in use is held in reserve in case of accident to anyone of the others. The automatic gauge at the Neshaminy is placed higher and protected . better than the gauge carried away last winter, and I think that no apprehension need be felt in regard to its injury from running ice. The three automatic rain gauges in use are in good condition, and have required but few repairs during the year. At present the Department possesses twelve ordinary rain gauges, seven of which are in good condition, three in fair condition, and two are unfit for use. [PAGE 263] The two current meters in the possession of the Department are at Point Pleasant, and are in fair order. The batteries and electric registers will require a few repairs to place them in good condition for use.Both levels used on hydrographic work were thoroughly overhauled and cleaned by the makers during the summer,. and one has not been used since; the other has had considerable usage, but is in fair condition.

Respectfully submitted,
Assistant in Charge of Hydrographic Work.

Monthly precipitation on sundry water-sheds, compared with U.S. Signal Service observations at Philadelphia.

Rain-storms of greatest intensity, as recorded by automatic gauges during 1886

Precipitation and streamflow in sundry watersheds

Average annual yield of sundry streams

Yield of sundry streams for the year 1886


Stream Flow, 1886, Perkiomen Creek at Frederick [346 kb]
Stream Flow, 1886, Neshaminy Creek below Forks [324 kb]
Stream Flow, 1886, Tohickon Creek [399 kb]

[PAGE 267]


RUDOLPH HERING, Engineer-in-Charge

Philadelphia, July, 1886.
MR. J. L. OGDEN, Chief Engineer.

SIR :--I have the honor to present to you the following report of progress of the surveys for a future water supply for the City of Philadelphia during the present year. As the investigation is completed, this report is also the final one. The office corps has been engaged in computing the stream flows of the Perkiomen, Tohickon, and Neshaminy creeks, in ascertaining the available storage in each of the respective valleys, in estimating its cost and in arranging and compiling the tables, maps, and charts for the final report.

The rainfall and stream-flow observations have been continued, though not as extensively as during the previous year. The rainfall stations at Sellersville, Doylestown, and Green Lane were abandoned January 1. The two automatic gauges are now at Frederick, Montgomery county, and at the forks of the Neshaminy, Bucks county; the ordinary gauges are at Seisholtzville, in Berks county, and at Quakertown, Lansdale, Ottsville, and Smith's Corner, near Point Pleasant, in Bucks county.

The stream-flow stations are confined to the Tohickon at Point Pleasant, the Neshaminy below the forks, and the Perkiomen at Frederick.

In view of the final results revealed by the investigation, it [PAGE 268] is quite necessary that both the rainfall and stream-flow observations be continued, at least near the Tohickon watershed, and it would be very desirable for future considerations to continue them, for the present also in the adjoining watersheds of the Neshaminy and the Upper Perkiomen.

In approaching the solution of the question as to where the city should go for better water, when the Schuylkill river is no longer a fit source of supply, the definite conclusions arrived at in the previous reports were substantially as follows:

  • Two sources present themselves as excellent and superior to all others, viz., certain tributaries of the Delaware and Lehigh rivers in the Blue mountains.
  • While either of these rivers, or both, must be made use of at some distant date, other sources are at hand which, at a much smaller outlay, will furnish water for some time of satisfactory quality and quantity.
  • It was found that the Delaware river above Trenton, the Tohickon creek and the Upper Perkiomen creek with its branches above Frederick (excepting the Macoby creek) would all furnish a supply to which, as far as the quality of water is concerned, no reasonable objection can be made. The selection of the best among these near sources, however, depended upon the quantity of water available from each, either directly or by storage, in order to supply the city daily with 200,000,000 gallons, and upon the comparative cost of securing this quantity.
  • The two latter questions were not fully answered in the last report. They have now been finally determined. The Upper Perkiomen creek and its branches cannot be relied upon to furnish more than 89,000,000 gallons per day during a year of minimum rainfall. An increase over this quantity would have to be obtained from the Blue mountains. The Tohickon creek could not be depended upon ordinarily to furnish more than 90,000,000 gallons per day, and in the minimum years not more than 80,000,000 gallons. An increase beyond this amount would have to be obtained from the Delaware river at Point Pleasant.
  • [PAGE 269] Estimates of cost for supplying 210,000,000 gallons daily, which was the amount to be provided for, and which can be conveyed to the city by an aqueduct twelve feet in diameter, show that the project contemplating the furnishing of 90,000,000 gallons of Tohickon water by gravity, and of pumping 120,000,000 gallons from the Delaware river by water-power, in other words, the "Point Pleasant scheme," is decidedly the most economical, and it is therefore the project recommended to the city in this report.

In reviewing the work done, and the detailed conclusions arrived at during the present year, I shall adhere as far as practicable to the order maintained in the previous reports of the subjects discussed.


But little needs to be added on this subject. Descriptions of the available routes to the different points where water could be obtained have already been given, and the best of them have been carefully surveyed, mapped, and studied, by means of profiles and estimates of cost. The aqueducts were estimated as having twelve feet in diameter and a grade of one in six thousand. In building the same it will be advantageous in many instances to deviate from a circular form, and other slight changes from the preliminary plans will be advisable. As the object of the present investigation was the solution of the broad question as to the best source for the future supply and the probable cost; it was not considered necessary to enter upon details regarding the construction of the aqueducts when the cost was not materially affected thereby.
Last year's report contains a map showing all the various practicable lines of aqueducts from the Blue mountains, from the Perkiomen and Tohickon creeks, and from other sources that had been considered. It contains further the profiles of the most available and important lines reduced from large and detailed drawings now on file in the Department. It finally contains detailed estimates of the cost of all of the aqueducts that were studied, from pages 334 to 349, a recapitulation of the same on' page 353, and a statement of their relative advantages [PAGE 270]
and disadvantages on pages 311 to 321. No information, therefore, is wanting to arrive at an intelligent judgment of their relative value.


The surveys made to ascertain the suitability of certain watersheds to furnish water of a good quality had also been completed before the present year and have been reported upon. The physical features, viz., the contour and elevation of the ground, the untillable areas, those covered with timber and those under cultivation, also the towns, villages, roads, &c., had all been mapped. The sanitary features, viz., the distribution and amount of population residing upon the watershed, their principal occupation, death rate, disposal of sewage, extent and character of mills, factories, slaughter-houses, cemeteries, &c., had also been ascertained and entered upon the maps, or described. The present report contains (Table 1) a tabular statement in detail of the statistics of the several proposed collecting areas of the Tohickon,. Neshaminy, and Perkiomen creeks, a brief summary of which had been given on page 350 of last year's report.

The following table shows the population on the proposed collecting areas:

Population on proposed collecting areas.

[PAGE 271] It will be seen that in the Blue Mountains there resides one person on every thirty acres, and in the Perkiomen, Tohickon, and Neshaminy watersheds one person on every six acres; a population which if distributed is in every case too sparse to seriously affect the condition of the water draining from any of the areas, In the case of the Tohickon and Neshaminy a fortunate circumstance permits the sewage from the only two centres of population to be diverted to other watersheds: Namely, the Doylestown drainage can be carried into Mill creek, and thence to the Neshaminy below the proposed dam; and the Quakertown drainage can be carried by a short sewer into the Perkiomen creek, if the 'Tohickon project is used in preference to that of the Perkiomen. This circumstance reduces the population per unit of area to less than that of the Perkiomen, and leaves it more generally distributed and less likely ever to affect the water.

During the present year a map has been compiled from the best attainable data, showing the available collecting areas north of the Blue Mountains between the Lehigh and Delaware rivers. An aneroid barometer survey was made and plotted over a portion of the same. to show the contour and elevation of the ground, but owing to insufficient funds the survey was not completed.

Attached to the present report is a chart, Plate II., which shows the triangulation made in 1884 over part of Bucks and Montgomery counties., described in the report for the same year. It should here be added that while it was not feasible within the allotted time to connect the triangulation with the United States Coast Survey station at Topton, a check upon the same was obtained by calculation through the triangle Topton-Geryville-Fagleyville, the result of which was quite satisfactory. The latter stations which had been determined from the line Haycock-Goathill checked within twelve inches.

There is also appended as Plate V. a section of topography near Point Pleasant, showing the manner in which the surveys were mapped. [PAGE 272] It might be repeated here that the large scale to which the surveys were plotted, viz., 400 feet to one inch, the comparative accuracy of the survey and the amount of detail contained on the map render them a valuable contribution to the survey of the State, inasmuch as they cover an area of 446 square miles in Bucks, Montgomery, and Lehigh counties. They will not only permit of a careful location of the geological features, but facilitate the detailed study of new railroad lines and other improvements.


In order to secure a supply of water which will be reliable in its quantity at all times, it is necessary to calculate only for the amount which the streams can ,furnish during the dryest [sic] years, as otherwise there would be a scarcity of water during such periods.

It is rarely possible, during the limited time granted for preliminary investigation, to observe the streams during a minimum year. Therefore it usually becomes necessary to obtain the desired quantities through deduction, by establishing the relation between the amount of rain and snow, which directly or indirectly feeds the streams, and the amount of water flowing in them, a relation varying somewhat with the topographical and geological conditions. Such a deduction becomes possible, if we know the minimum quantity of rain that can be relied upon.

Rainfall observations in this section of the country have extended over many years. In Philadelphia they have been recorded for over half a century. It is possible therefore to state with considerable accuracy what the least precipitation is likely to be, and how often droughts may be expected. But the quantity of rain falling in Philadelphia is not the same list that falling upon the watersheds in question, owing to the difference in elevation and other causes. Even in the city itself it varies with the locality and the position of the gauges. Fortunately these differences are very nearly constant quantities, [PAGE 273] because the conditions causing them remain the same. By observing and comparing the precipitation at a number of points in or near the watersheds, these differences may be ascertained during a period of several years with some precision, and thus the last link would be supplied in the process of determining the probable minimum flow of the streams under investigation.

Records of the rainfall in Philadelphia have been kept at the Pennsylvania Hospital since 1825. They are given in Table 5. To permit of a more thorough analysis I have added Table 6, giving the maximum and minimum falls per month, quarter, year, and two years, and have also given the order of the months with relation to their degree of humidity. The quarterly totals and the two annual totals, one limiting the year from January 1 to December 31, the other from October 1 to September 30, have also been added. On account of the small stream-flow in the early fall it is better to reckon the year from this season instead of from January 1; because while slight rains just before or just after January 1 almost invariably produce high water and greatly change the total of the respective year. heavy rains about the first of October generally cause freshets of little importance.

An examination of these tables I think justifies the assumption that the minimum precipitation per annum, as recorded at the Pennsylvania Hospital, could be assumed at 33.6 inches, or 76 per cent. of the mean annual fall, the actual minimum records being 33.53 inches for 1827 and 33.93 inches for 1856., The apparently remarkable low record of the year 1825, viz., 29.37 inches, being the first in the series, may have been undermeasured [sic] and should hardly receive the same weight as the records of more recent years. Further, the precipitation of the years. preceding and succeeding the minimum year 1856 is considerably greater, viz., 44.1 and 48.3 inches, which would have a favorable effect on the stored quantity of water in the reservoirs at the beginning of the year 1856, and also in supplying any deficiency early in the following year. By reckoning [PAGE 274] from October 1 to September 30 we get a minimum of 39.20 instead of 33.93 inches.

To throw still further light on the question I have compiled the following tables showing the minimum precipitation at points within 150 miles of Philadelphia.

Precipitation in percentages of means within 150 miles of Philadelphia, during years of minimum precipitation

The numbers indicate the percentages of the mean rainfall of each locality. The years of extreme drought in this neighborhood appear to have been 1825, 1834, 1848, 1856, 1870, 1874, 1880. A glance at Table 8 shows that the year 1825 was no doubt phenomenal in its low rainfall, extending from Washington to Philadelphia, and Morrisville, New Jersey. Other extremely low records, though more local, are found to be 62 per cent. of the mean for Washington in 1848, and 56 [PAGE 275] per cent. for Baltimore in 1856. The existence of these few instances has not caused me to lower the assumed minimum for Philadelphia below 76 per cent. of the mean, because the table indicates that the minimum quantity in most of the localities has been increased, and that in Philadelphia no rainfall has been lower than the assumed figure since 1826. Low quantities are recorded for some of the cities during years not given. They were omitted in the table because the intention was to compare the rain of the surrounding territory with that of Philadelphia, only during the years of minimum fall in the latter, in order to show the extent of the droughts in this neighborhood.

The following table, recording the minimum precipitation for two-year periods, still further justifies the assumption that I have made. All localities within the 150-mile radius show that while a single year minimum has given slightly less than 76 per cent. in a few instances, a two-year minimum has not done so anywhere since 1826, except towards the south in Baltimore and Washington. As a basis for comparison I have selected the U. S. Signal Service station in Philadelphia. As it has been in existence only since 1872 it was necessary to discover the constant difference between this station and the hospital. which would be due to the different positions of the gauges, the one at the hospital being near the surface of the ground and the Government gauge being upon the high roof of the post office building. The observations at the hospital have lately, not always, been taken with the greatest care. In the winter of 1884 to 1885 we found that snow was being measured as such, and not as melted snow. In 1874 and 1881 the annual amounts vary considerably from those recorded by the Government. In the latter year no apparent reason was found, but in the former it seems, on comparing the single rainfalls, that some of them had not been recorded at the hospital, although the [PAGE 277] rain was shown to have been steady and prolonged hardly a quarter of a mile away at the post office building.

Precipitation in percentages of means within 150 miles of Philadelphia, during two-year periods of minimum precipitation,
the numbers being the average per year.

It seems that the fall at the hospital may be taken at 112, if that recorded by the Signal Service is 100. Then, as the minimum rainfall at the former was assumed to be 33.6 inches, the minimum fall at the latter should be taken at 30 inches per annum.

Comparison of Rainfall, recorded by the U.S. Signal Service and the Pennsylvania Hospital, in Philadelphia.

The next step which became necessary was to establish the minimum precipitation upon the watersheds to be investigated. The quantity falling upon them since the beginning [PAGE 278] of the surveys has been reported every year, but not until last year was it practicable to make a comparison, because of the short period over which the observations had extended (see Table, Report, 1885). The rainfall at the various stations was expressed in percentages of the fall recorded at the Government station in Philadelphia. Unfortunately some of the totals were incorrectly printed. They should have been as follows: (See Table 7.)

[Table of Corrected Rainfall Figures]

[PAGE 279] A longer time will be required to arrive at percentages which will represent the true mean values. For the present I have assumed the above results as being the best available data for the purpose. In order to determine from them the quantity of rain representing the average fall upon each of the water-sheds which could be used for storing water, it was necessary to carefully compare their topographical features, their mean elevation, the wooded areas, the relative amount of exposure to the rain-bringing winds and the elevation of the gauges above the surface of the ground. This comparison indicated the results as given by Table 11.

The minimum precipitation on the different water-sheds is given both in inches and in percentages of the rainfall recorded at the Signal Service Station in Philadelphia. The average minimum monthly falls are given in inches. Their relation to the annual fall was obtained from the ratios of the mean monthly to the mean annual fall at Philadelphia, as given in the first column of the table. It will be evident that the figures for each separate month cannot represent the absolute minimum for said month, but only the average minimum, and that therefore the mean monthly stream-flows, which were estimated from these figures, also do not represent an absolute minimum flow during the month, but an average. Inasmuch as the storage reservoirs hold and equalize the flow for over half a year, the latter quantity is the proper one to use in calculation.

It is to be hoped that the rainfall observations on the watersheds in question can be continued, so that these quantities may be established with a greater degree of precision, in order to make it possible to better adjust the size of the storage basins. As the stream-flow is less than the consumption from about May 1 to December 1, the minimum rainfall of this interval should be deduced from the records of the Pennsylvania Hospital gauge, before the sizes of the storage basins are finally determined.

I have appended to this report, as Plate VIII., a specimen sheet of the rainfall charts showing how the records have been [PAGE 281] plotted. They admit of ready comparison, and indicate at a glance the depth of fall by the blue -lines representing each separate fall, and also the rate by the degree of their inclination.

Deduced average minimum rainfall on sundry watersheds

I have also appended, as Plates VI. and VII., drawings of the ordinary and of the automatic gauges. The former were made by Messrs. Schultzbach & Co., in Washington, the latter by Messrs. Black & Pfister, in New York.


Not until during the present year has it been possible to present the results of the stream gaugings since the beginning of this investigation, because we had been unable to obtain certain necessary measurements of high flows until last winter, which it was essential to have before the high flows of previous years could be computed. In former reports the methods of gauging streams have been described. It therefore remains now only to state the results thereof. The daily flow where gauge stations had been established has been tabulated, and the records are on file in the department. Tables 12 and 13 of this report show the monthly and annual yields of the streams. On Table 13 the first column gives the area, the second the average rainfall, and the last the average flow per second per square mile. I have added for comparison similar data concerning the streams supplying New York and Boston with water, viz., the Croton and Sudbury rivers. For reasons already mentioned the years have been reckoned from October 1st to September 30th. The results of only two such years could be embodied in the table. The first year shows a flow above the average and the second a flow below it. The results of the Sudbury and Croton rivers are derived from observations extending over six years. It is interesting to note that the Tohickon creek gives the greatest average yield per square mile, and the Perkiomen creek above Green Lane the next greatest, while the North East Branch of the Perkiomen gives the least.

Annual yield of sundry streams.

[PAGE 283] Table 16 gives the maximum and minimum daily flows that have been observed in our watersheds and in those of the Sudbury and Croton rivers. It will be noticed that the least summer flow is generally found in those streams that also have the greatest winter flow. The Perkiomen at Frederick has the largest summer flow per square mile of any of the streams observed, which no doubt is due to the mountainous and wooded region near its head. The variation in the flow during the different months is .very great. It is apparently even greater here than in the Croton and Sudbury rivers. The Perkiomen has a smaller maximum and larger minimum flow than the Tohickon and Neshaminy creeks, due to the somewhat greater rainfall in the higher altitudes of the Perkiomen watershed, and partly to the greater area of wooded territory, which tends to retain the water and deliver it into the streams more gradually.

Tables 14 and 15 are summaries of the flow in different streams for each month. In one table the flow has been reduced to cubic feet per minute per square mile; in the other, to ratios ?f the average monthly quantities. In these forms the results of our gauges have been compared with the quantities given by Fanning in his treatise on "Water Supply" for the Cochituate and Sudbury rivers in Massachusetts, and for the Croton and West Croton rivers in New York. An examination shows again that our creeks have a larger proportion of flow in the winter months and are dryer in summer than the Massachusetts and New York rivers. This is due partly to the lower latitudes of the former, permitting the accumulation of less snow, but mainly to the larger proportion of cultivated and open ground in our watersheds, which allows the rainwater to run off more rapidly.

Plate IV is appended as a specimen of the stream-flow charts, showing the discharge for every day in the year and having for comparison both the rainfall and the daily temperature plotted. Plates XI, XII and XIII show the various stream gauges which have been previously described.

Table showing minimum and maximum daily flows in sundry streams

[PAGE 285] From the facts recited it is clear not only that our streams will require very large storage reservoirs to equalize the flow for a uniform daily delivery throughout the year, but that there will be required a greater proportionate storage capacity than on the Sudbury and Croton watersheds. In order to calculate the required amount of storage the minimum stream flow must first be determined. This quantity, as already said, is obtained from the minimum rainfall upon the watersheds. As this has been given above, it remains to discover the relation between the rainfall and stream flows, or, in other words, the proportion of the rain-water reaching the creeks.

Tables 17, 18, and 19 contain the percentages of rain flowing off the watersheds in question. For comparison I have added the same percentages recorded for the Croton, Cochituate, and Sudbury watersheds. The last line of Table 17 gives the monthly percentages that were finally assumed for our cases. Generally they are practically the same as those found by observation during the last two and a half years, and given in the first line of the table. It was thought well to decrease them somewhat for January, February, and March in the winter, as it seemed probable that our observed results were greater than they would be for a longer term of years. The figures from June to October were likewise decreased for the same reason.

As these percentages were to be applied to the minimum and not to the average rainfall, the question arose whether they would hold good for minimum years. Inasmuch as the difference would be small, and as further time is required to establish a number of points, for instance, the actual minimum rainfall upon the watersheds, which might affect the result in a greater degree, it was deemed sufficient for the present to assume the percentages to be the same. It is evident, however, that they cannot be alike for all of the watersheds under consideration owing to the different topographical and other conditions. Yet with the limited time at our disposal and [PAGE 287] with the rainfall and stream-flow, observations extending over 80 short a time, it was decided to use them only as an average for the whole territory, leaving it for the future to discover the percentage for each special watershed.

Average monthly percentages of rain flowing off sundry watersheds

Annual Precipitation on Sundry Watersheds, and Percentages of same reaching the Streams.

Table 20 contains the results as derived from the above data. It gives the supposed minimum yield for each stream for each month and the daily average for the year, It is not understood that during anyone month the computed flow represents the least flow that can be counted on during the same, for Table 12 shows that this is not the case, But it is understood that for the whole minimum year there will be a general distribution resembling that which is given. As it will be [PAGE 288] necessary during such a year to draw water from large storage reservoirs capable of holding more than half a year's supply, the particular flow during one month is of no importance as compared with the average flow for several months.

The computed average minimum daily yield in million gallons from each watershed is as follows; Tohickon, 86.5; Neshaminy, 112.1; Perkiomen at Frederick, 129.3; Perkiomen at Green Lane, 60.1; East Swamp creek, 40.3; West Swamp creek, 43.4; North East Branch, 49.7.

From what was said above it will be evident that these values must be too great for some areas and too small for others. This will not be a serious matter, however, for the present purpose, as the average topographical conditions for each of the two gravity schemes remains nearly the same. The Neshaminy resembles the North-east ranch and the West Swamp creek of the Lower Perkiomen, while the Tohickon resembles the Upper Perkiomen. The error that is made will tend to give a greater quantity than would actually be available for the lower and open watersheds and a smaller quantity for the Upper Perkiomen and Tohickon. We can see that this is really the case by comparing the flows for 1885, which closely approach a minimum year, with the flows deduced by means of the assumed percentages from the minimum rainfall. Expressed in million gallons per annum the following table gives the yield of the different watersheds for 1885, the computed minimum yield and the resulting differences.

The Neshaminy, West Swamp creek and North East Branch show that the estimated minimum flows are too great, while those of the Tohickon and Upper Perkiomen are probably not large enough. Rounding off the figures and taking this point . into consideration, we may designate the probable average minimum daily yield in million gallons to be as follows: Tohickon, 90; Neshaminy, 110; Perkiomen at Frederick, 130; Perkiomen at Green Lane, 61; East Swamp creek, 41; West Swamp creek, 41, and North East Branch, 46.

Average minimum flow deduced from assumed minimum rainfall

Minimum stream flows in million gallons

[PAGE 291] It was found that a uniform delivery of 25,000,000 gallons a day from the Neshaminy dam would supply all the mills below it and obviate the necessity of paying damages to riparian owners. This quantity of water has been provided for in the estimates, and it may be added that the 25,000,000 gallons can, if properly utilized, develop two hundred and fifty horsepower at the dam in descending to the stream. But while it is possible to spare enough water for compensation from the Neshaminy creek, owing to the practicability of pumping any deficiency from the Delaware river at Point Pleasant, it is not possible to spare it in the Perkiomen valley without curtailing the available supply for the city. During the dry seasons the entire quantity would be needed by it. I have therefore included in the estimate for the Lower Perkiomen scheme the value of all the mill privileges between Schwenksville and the Schuylkill river, amounting to $130,000, and in the estimate for the Upper Perkiomen scheme between Green lane and the Schuylkill, amounting to $160,000. These figures are included in the amount given in Table 35 under the heading "Cost of Storage." If a compensation of 25,000,000 gallons daily must be given to the riparian owners, the available amount for the city from the Perkiomen would be reduced to 169,000,000 gallons during the years of minimum rainfall.

The Delaware river below Point Pleasant (see Table, page 351, Report of 1885), having a minimum flow at this point of some 1,500,000,000 gallons daily, would not be damaged by the extraction of 200,000,000 gallons.


From an inspection of the territory and with the assistance of the topographical maps all the available sites for storage or impounding reservoirs were noted. Tables 22, 23, and 24 give a list of the same, with their principal features indicated, together with the cost of storage in each case. Time did not permit of making as detailed a study of the more important [PAGE 292] ones as would be desirable for an accurate estimate of the cost. The capacities were computed from the contour lines as taken from the general maps, and the profiles of the sites for dams were taken in most cases likewise from the contour maps, special surveys having been made only in a few cases. For preliminary estimates, however, the results are sufficiently close. Plate I. is a general map of the entire water-shed investigated, showing all the reservoir sites that .were considered. The total storage capacity in the Tohickon watershed is over 25,000,000,000 gallons, and in the Neshaminy about 23,400,000,000 gallons. In the Perkiomen watershed there is a capacity beyond what could be used, and a selection of the best and least expensive sites was possible. In the Lehigh watershed rough approximations had to be made because there was no time for more detailed work, nor aid the necessities of the case absolutely demand it. The natural facilities for impounding water in most of the valleys are quite good, and the expense is therefore not excessive. The cost of the principal reservoirs, for instance, is as follows:

Tohickon valley at Hancock, about 18,000 mill. gal. at $82.53 per mill:
Perkiomen valley at Green Lane, about 12,000 mill. gal. at $93.88 per mill.
E. Swamp creek valley at Millville, about 8,000 mill. gal., at $103.13 per mill.
W. Swamp creek valley at Zieglersville, about 12,000 mill. gal. at $76.21 per mill.
N. E. branch at Lederachville, about 15,000 mill. gal. at $100.20 per mill.

The average cost of the storage basins in the Croton valley is given at $200 per million gallons, and the estimated cost of the large Croton reservoir, about to be built, as $125 per million gallons.

In order to select the reservoirs that are required from the list contained in Table 22, it is necessary first to ascertain the amount of storage which must be provided in each valley to equalize the flow.

[PAGE 293]

Relative consumption of water in Philadelphia.

With the data contained in the previous pages, it would now be possible to estimate the same for the constant delivery of a uniform daily supply. As the supply, however, is not quite uniform, the summer months showing a greater consumption per day than those of the winter, it remains to ascertain what quantity of water is likely to be needed during each month. Table 25 has been prepared for this purpose from the experience gained in Philadelphia during the last six years.The values are percentages of the average daily supply for the year, or the actual number of million gallons per day, if the average daily supply for the year is 100,000,000 gallons. It will be seen that while in August the consumption is 15 per cent. greater in January and February it is 15 per cent. less than the average.

The quantity of water which must be impounded in a given watershed increases in a greater ratio than the supply to be daily furnished. As the latter becomes greater in proportion, not only a larger quantity of stored water must be drawn, but it must be drawn for a longer time, because the period when the stream carries a deficient amount becomes longer. In the Sudbury watershed, in order to furnish 70,000,000 gallons daily, a storage capacity is required of 2,909,000,000 cubic feet, and for 40,000,000 gallons daily, a capacity of only 450,000,000 cubic feet is needed. The reservoir capacity is [PAGE 294] in a ratio of 6 1/2 to 1, while the daily supplies are in a ratio of 1 3/4 to 1.

In the Croton watershed, in order to furnish 100,000,000 gallons daily, a storage capacity of 1,200,000,000 cubic feet is required; for 200,000,000 gallons a capacity of 4,000,000,000 cubic feet, and for 300,000,000 gallons daily, a capacity of 7,300,000,000 cubic feet. The reservoir capacity is in a ratio of 6 to 3-1/2 to 1, while the daily supply is in a ratio of 3 to 2 to 1. It is evident that the expense of storage becomes comparatively great when the amount of water used approaches the total flow of the streams. From the average minimum daily yield of the creeks that we are considering, it will be seen that the entire flow during years of minimum rainfall must be impounded in order to furnish the required supply.

With the above data it is now possible to compute the necessary storage capacity for each valley. Tables 26 to 31 inclusive, give the results for the Tohickon, Neshaminy, Perkiomen at Green Lane, East Swamp, Perkiomen above Schwenksville, and the North. East Branch valleys. Column 1 in each table contains the monthly stream-flow; column 2 the loss by evaporation and percolation from the reservoirs; column 3 the water consumption for each month; column 4 the water added to or drawn from the reservoirs, and column 5 the water stored in the reservoir at the end of each month. Inasmuch as May is usually the first month in which the consumption exceeds the stream-flow, it has been assumed that the reservoir shall be full at the end of April. At the end of November, on the other hand, the reservoirs would be drawn down to the lowest point. To provide for the contingency of an extremely dry summer and fall, and also to prevent the necessity of drawing all the water from the reservoir at any time, it has further been assumed that the amount of water in the reservoir at the end of November should be equal to two months' consumption. [PAGE 295] In order to study this question further, the lowest possible rainfall for the seven months, from May 1 to November 30, should be carefully considered with the aid of the long record at Philadelphia given in Table 5.

With these conditions the tables give the following requisite storage capacities and the greatest mean daily supply for the different watersheds:

Tohickon, 2454 mil. cu. ft., 80 mil. gals. daily.
Neshaminy, 3181 mil. cu. ft., 101.3 mil. gals. daily.
Perkiomen, at Green Lane, 1705 mil. cu. ft., 52.8 mil. gals. daily.
East Swamp creek, 1144 mil. cu. ft., 36.2 mil. gals. daily.
Perkiomen, above Schwenksville, 4829 mil. cu. ft., 151.2 mil. gals. daily.
North East Branch, 1402 mil. cu. ft.,. 43.5 mil. gals. daily.

It will be seen that the Tohickon and Neshaminy, embodying together one project, could not furnish more than 181.3 million gallons daily; the entire Perkiomen, above Schwenksville, together with the North East Branch, not more than 194.7 million gallons; and the Perkiomen, above Green Lane, with the East Swamp creek, only 89,000,000 gallons.

At the beginning of the investigation it appeared probable that a very close discrimination might be required between the different watersheds, because their general character was quite similar. Besides making a careful topographical survey and gauging of the rainfall and stream-flow at as many points as possible, it was thought desirable also to have at hand whatever data might otherwise throw light on the relation between the rain and stream-flow from the separate areas. It was therefore concluded to abstract the following data from the topographical maps, which would assist in this direction. The areas were divided into vertical sections; the first comprising all the territory between 0 and 200 feet elevation; the second that between 200 and 400 feet elevation, and so on, each section being bounded by a 200 feet contour line. This division would facilitate the making of a mean profile of the areas and of their respective surface characteristics, with which a better interpretation of the above relation might be obtained. [PAGE 296] The surface characteristics noted were the areas of the ground slope less than 2 feet per 100, between 2 feet and 20 feet per 100 and over 20 feet per 100; also the areas of the roads, of the cultivated soil, of the wooded and untillable ground and of the swamps and meadows. Tables 2 and 3 contain these data.

In addition to this compilation some field work was undertaken, which in connection with other work, could be done without much expense. Certain areas of, different surface characteristics were staked out, a rain gauge set up in the middle of each, and a meter placed at the lowest point to measure the water which ran off during each rain. A comparison of the general rain and stream-flow with the data in the above compilation would have been very much facilitated by these observations.

Should the progress of the investigation have made it certain that only stored water from the Perkiomen and neighboring watersheds could be used for a future supply, it would have been necessary to enter into the question of storage and available quantity more fully, and these data would have become useful As, however, the economy of procuring the Delaware water at Point Pleasant and the superior quality of the water in the Tohickon ,watershed as compared with the Neshaminy, and particularly of the Lower Perkiomen, became evident, it was not considered essential to spend the necessary time for the comparison outlined above. The deductions which have been made above and the results reached therefrom were considered sufficiently close under the circumstances.

After having determined the amount of storage required, the most suitable reservoirs from among those given in Table 22 were chosen. It was evident that certain reservoirs were absolutely necessary, although their selection incurred either a heavy expense or other disadvantages. For instance, Reservoir No. 7 at Schwenksville had to be selected, although flooding several villages, because the water required a delivery [PAGE 297] at a certain elevation, and Reservoir No. 1 at Sumneytown required a long conduit to deliver the water into the main aqueduct.

Among determining elements also the following should be considered. The larger the reservoirs the better will be the quality of the water. A large surface facilitates wave action, and thereby a better aeration of the water, which is quite essential where the creek water to be stored comes from agricultural areas. Large and long reservoirs act also as excellent settling basins, because the slow velocity of the water passing through them allows the suspended particles to settle. Deep reservoirs, further, keep the water cooler, cause less evaporation, and retard the growth of organic matter. Steep banks allow a minimum amount of surface to be alternately wet and dry, consequently to develop low vegetation which is injurious to health. Table 23 gives the flooded areas for each 10 feet elevation, and permits this point be to readily considered. The lower down the reservoirs are in the valley the more rapidly will rains fill them after having been drawn down.

The geological structure of the valley sometimes has a great effect on its ability to store water. If the stratification across the valley is synclinal, it will favor the retention of the water, while if it is anticlinal it will facilitate leakage. Fissured trap rock which forms the dyke at Schwenksville through which the Perkiomen has worn its path, would allow water to escape more readily than compact rocks. The question of percolation has, however, not been considered a serious one. The water from all the creeks is more or less muddy after rains, and the fine silt will in a short time close the pores of the porous materials and practically make them water-tight. Want of funds precluded a geological survey of the proposed reservoir sites.

On the Neshaminy watershed everyone of the available sites is needed to furnish the required supply. In the Tohickon valley Reservoirs No. 1 and No. 2 were selected as [PAGE 298] being the best. For the Upper Perkiomen scheme it was necessary to consider the proper storage in each of the several valleys. In that of the East Swamp Creek Reservoirs No. 1 and No. 2 were chosen, although not particularly favorable sites. Reservoir No. 5, at Green Lane, was the best one for storing the water of the Perkiomen, and Reservoir No. 8, at Dale Forge, for storing the water of the West Branch. Reservoirs No. 1 and No. 8 were the best in the valleys of the North East Branch and the West Swamp creek. Reservoir' No. 7, finally, was necessary to store the water above Schwenksville.

Table 32 gives the list of these reservoirs, with their capacity and cost. It will be seen that the average cost per million gallons is $122.70 for the Tohickon, $165.89 for the Neshaminy, $133.61 for the Upper Perkiomen, $135.31 for the Perkiomen above Schwenksville, and $100.20 for the North East Branch. A brief description of the selected reservoirs follows:

Reservoir No. 1 of the Tohickon watershed was located at a point about one mile north of Point pleasant, where the valley is quite narrow, and separated from the Delaware river by a distance of only 1700 feet, which makes its location favorable for an extension of the aqueduct further up the Delaware river. The dam will also serve the secondary purpose of a crossing for the aqueduct when extended, thus saving the expense of syphoning [sic]. The height of the dam at the deepest point is about 150 feet, including the foundation, and the extreme length is 946 feet. The flooded territory covers an area of 316 acres, which is about one-half covered with timber, and is of little use for cultivation, owing to the steep rocky nature of the ground. There would be flooded: 1 grist-mill, 1 grist and saw-mill, 6 dwellings, and 2 barns. There is also 1 grist and saw-mill below the dam, which would have to be abandoned.

Reservoir No. 2 is located on the Tohickon creek, just below the mouth of Haycock run, and forms a very large reservoir, being capable of storing about 18,000 million gallons, [PAGE 299] and extending back 7 1/2 miles. For the most part the valley is favorable for a reservoir, the slopes drop off quickly and the valley widens above the dam to large proportions. The territory to be flooded is mostly under cultivation, the wooded area not being more than about one-third of the whole. The dam is 100 feet high above the creek, and 1,510 feet long. It floods an area of 1,829 acres, with 7 grist and saw-mills, 2 creameries, 1 tannery, 35 dwellings, and 27 barns.

It was found that while there was an abundance of storage capacity on the Little Neshaminy, only a portion of the flow could be stored in the valley of the Big Neshaminy without going to a great expense. By a fortunate circumstance it is practicable to store the water of the latter in the reservoir of the former by connecting the two valleys with a short tunnel 12 feet in diameter. Reservoir No. 1 is situated on the Little Neshaminy, three-fourth or a mile above its mouth. It has a favorable site for a dam, as the sides of the valley approach each other sufficiently to make its extreme length 1,550 feet, and extreme height 98 feet, while the valley opens out to three-fourths of a mile in width. The slopes of the reservoir vary from steep to nearly level, but for the most part they are steep. The dam backs water over 2,531 acres, of which 189 acres are wooded, and it floods 88 buildings, as follows: 4 grist-mills, 2 saw-mills, 2 school-houses, 2 chapels, 1 creamery, 41 dwellings, and 36 barns. Owing to the great width between the banks, and the bays formed by tributary creeks, the cost of changing the location of the roads and of bridging is very large.

The Big Neshaminy is such a wide and open valley throughout that it was difficult to decide on a suitable location for a dam. The point selected is 1 3/4 miles above the forks. The right bank of the valley rises up almost perpendicularly over 100 feet, but the left bank rises gradually at a grade of about 7 feet per hundred to the proposed height of the top of the aqueduct, from where it continues nearly level for a distance of over 4,000 feet, thus requiring a very long dam. It [PAGE 300] is proposed to build 1,200 feet of masonry across the valley, and the remaining 4,725 feet of earth. The greatest height of the dam, including foundation, is 89 feet, and the area flooded covers 2,273. acres, of which 203 are wooded. The territory flooded has a long, irregular shape, its length is about 11 miles, and it reaches as far back as New Britain. The slopes of the valley average from 5 to 12 feet par 100 over a surface that will alternately be covered with water and again exposed, except at the extreme upper end, where level and shallow areas occur that will have to be kept flooded by subsidiary dams. The storage capacity of the reservoir is not more than one-half of the size required to store the minimum flow of the stream, the remainder being provided for in Reservoir No. 1 on the Little Neshaminy. Seventy-two buildings will be flooded, viz.: 7 grist and saw mills, 1 store, 1 schoolhouse, 38 dwellings, and 25 barns.

Reservoir No. 3, on the north branch of the Neshaminy, floods an area of 369 acres, which is nearly all cultivated. The average slopes of the sides of the valley are about 5 feet per 100. The height of the dam is 47 feet, and its length 1,420 feet. The sites of 1 mill, 7 dwellings, and 2 barns will be submerged.

Reservoir No. 1 of the Upper Perkiomen is located on the East Swamp creek, above Sumneytown. The dam is 71 feet high and 1,030 feet long, and floods a valley of 196 acres heavily wooded. The sides of the valley are steep and in some places precipitous, forming a deep and narrow reservoir. The country is of little value for farming purposes. The dam floods 2 mills, 8 dwelling-houses, and 2 barns. If not used in connection with the Lower Perkiomen scheme it will be necessary to connect this reservoir and Rich Valley creek with the main aqueduct at Green Lane or Perkiomenville by constructing a branch conduit.

Reservoir No. 2 is located on the East Swamp Creek below Millville, and covers over 1,648 acres, of which 232 are wooded. The valley at the lower end has steep slopes, but the upper [PAGE 301] portion is comparatively level, so that about two-thirds of the reservoir has a shallow depth varying from 10 to 20 feet, which is exposed when the water is drawn down. The dam is 55 feet high, including foundation, and 800 feet long. It floods 5 grist and saw mills, 1 hotel, 24 dwellings, and 7 barns.

Reservoir No. 5 is located on the Perkiomen creek just above Green Lane. The site is a very favorable one for a dam, the valley being narrow and steep at this point, and widening out above it to large proportions. The territory flooded covers an area of 1,705 acres, of which 209 are wooded. The reservoir slopes are steep for the most part as far up as Red Hill. Above this point they begin to flatten, and in some cases become nearly level, forming shallow areas from 10 to 15 feet deep, exposed during low water. Seventy-nine buildings will be flooded, viz., 6 grist and saw mills, 36 dwellings, and 37 barns. The height of the dam, including foundations, is 95 feet, and the length is 634 feet. About one-third of the territory flooded is good farming country.

Reservoir No. 8 is situated on the west branch of the Perkiomen creek near Dale Forge. It is the highest of all the reservoirs proposed, being 609 feet above tide-water, and floods only a few important buildings; The height of the dam is 78 feet, and its length 384 feet. The flooded area is 226 acres.

Reservoir No. 1 of the Lower Perkiomen scheme is located on the North East Branch west of Lederachville. The dam is 100 feet high and 4,025 feet long, more than half of which has an average depth of only 8 feet. The dam floods an area of 1,928 acres, of which 117 are wooded. The slopes of the reservoir are generally good, and there are but few shallow places except at the extreme upper end. The area flooded is generally good farming land, with 99 buildings, as follows: 5 grist and saw mills, 1 meeting house, 1 hotel and store, 58 dwellings, and 34 barns. This reservoir is connected with the main aqueduct by an auxiliary conduit nearly one mile long.

[PAGE 302] Reservoir No. 7 is located on Perkiomen creek, above Schwenksville. The dam is to be built in the gorge at Zieglersville station, and floods 2,307 acres. Its capacity is limited only on account of the villages Green Lane and Sumneytown, which are situated on the proposed banks of the same; The available depth of water is only 12 feet. The dam is 99 feet high and 1,430 feet long. Two small villages, viz., Frederick Station and Perkiomenville, are flooded out entirely, and of Sumneytown and Zieglersville the lower buildings.

The slopes of the valley are good, and about one-seventh of the flooded area is wooded. Two hundred and fifty-four buildings would be submerged, viz., 15 grist and saw mills, 1 planing-mill, 1 powder-mill, 4 hotels, 1 tannery, 2 creameries, and the remainder are dwelling-houses, barns, and ice- houses. From the proposed dam to near Green Lane the present line of the Perkiomen Railroad would also be flooded, and an estimate was made for the following new location: Leaving the present line south of Schwenksville, and extending up the valley to the left at a maximum grade of 50 feet per 100, it crosses the proposed reservoir south of Zieglersville, and then extends due north until it again reaches the present line just below Green Lane. In this reservoir, and also in the following one, the change of roads, bridges, etc., will be very costly on account of the large area and configuration of the territory flooded.

Reservoir No. 8 is located on the West Swamp creek, a little over three miles above its mouth. The location for the dam is the most economical one of any that have been proposed. The valley at this point is a narrow gorge, and immediately above it widens out into a large basin of 2,301 acres. The reservoir thus formed covers a flat and nearly level country, so that over a large portion the water is very shallow. The slope of the ground averages not more than 2 feet per 100, which leaves a large area exposed at low stages of the water. The country is a good farming district with very little woods, the latter covering about one-tenth of the area. The dam is [PAGE 303] 85 feet high and 498 feet long. Five grist and saw mills, 1 tannery, 3 stores, 51 dwelling-houses, and 28 barns would be submerged.


The economical feature of the project for obtaining water at Point Pleasant lies in the existence of an undeveloped waterpower sufficient to raise into the aqueduct a daily quantity of Delaware water equal to 120 million gallons during the low-water stage. A close examination with a view of utilizing the same was made last spring. The site of the proposed dam is above the bridge; its elevation is assumed at 85 feet above tide-water, which backs the water to the head of Wharford's First Rift, or about one and one-half miles; and gives an available head of 15 feet. The flood waters, based on the freshet of 1862, would raise the level of the pool 20 feet. It would therefore be necessary to raise the tracks of the Belvidere Division of the Pennsylvania Railroad about 10 feet, and to protect the canal at the proposed dam with double gates, to be used in times of extreme high water.

The minimum flow of the river was assumed at 1,500 million gallons per day (see Table, page 351, Report of 1885). Deducting the quantity to be raised into the aqueduct, there will remain enough water to supply power equivalent to 3,640 horse-power. Assuming that the motors employed will utilize 80 per cent. of the theoretical power, there will remain 2,912 actual horse-power. The aqueduct at Point Pleasant is 217 feet above tide-water. Adding for friction, etc., the lift of the pumps would be 137 feet. The pumping mains are 30 - inches in diameter, and the distance to the aqueduct is 600 feet, The velocity in the same is assumed to be 3t feet per second. Computing the loss by friction of the pumps at 3 per cent., it is found that 117,463,000 gallons can be raised into the aqueduct every twenty-four hours during the lowest stages of the river. As it is practicable to supply a much larger quantity of water during ordinary stages of the river, and at [PAGE 304] favorable times to pump into the lower storage reservoir of the Tohickon valley, I have assumed the available capacity of the Delaware river to be 120 million gallons per day with a slight increase of cost.

Table 33 gives the cost of the water-power in detail as prepared by Mr. Harvey Linton, assistant.

Cost of Water-power at Point Pleasant.

[PAGE 305]


The following persons have been engaged on the work:

Engineer Corps.
F. L. Paddock, Principal Assistant, June 1, 1883 to July 31, 1886.
Harvey Linton, Assistant, May 20, 1883, to February 28, 1886.
C. S. Gowen, Assistant, June 24, 1883, to February 28,1884.
H. W. Sanborn, Assistant, July 20, 1883, to May 31, 1886.
Geo. B. Mifflin, Assistant, June 12, 1883, to June 30, 1886.
W. T. Forsythe, Assistant, June 10, 1883, to November 30, 1885.
Kenneth Allen, Assistant, May 30, 1883, to November 30, 1885.
A. P. Berlin, Assistant, July 19 to September 4, 1883.
E. C. Bull, Sub-assistant, June 5 to December 20, 1883.
C. E. Taylor, Sub-assistant, June 18, 1883, to November 30, 1885.
George S. Cheney, Sub-assistant, June 4, 1883, to October 31, 1885.
William E. Parker, Sub-assistant, September 10, 1883, to June 30, 1886.
H. A. Schofield, Sub-assistant, May 28, 1883, to June 30, 1886.
Amasa Ely, Sub-assistant, May 28, 1883, to date.
E. A. Miller, Sub-assistant, June 1, 1884, to July 31, 1886.
J. P. Watson, Rodman, June 1 to December 31, 1884.
William S. Gleim, Rodman, July 14, 1884, to May 30, 1885.
H. Taylor, Rodman, September 24 to December 24, 1884.
A. P. Allen, Rodman, September 1 to October 31, 1884.
F. D. Jones, Rodman, November 1 to December 24, 1884.
R. T. Vaughan, Rodman, May 30 to December 22, 1883.
Max Atlee, Rodman, May 28 to December 22, 1883; June 1 to July 12, 1884.
[PAGE 306]
Jacob Stadleman, Rodman, June 4 to July 7, 1883.
Isaac Forsythe, Rodman, June 4 to December 20, 1883.
C. P. Bassett, Rodman, July 23 to August 17, 1883.
E. S. Crawley, Rodman, June 25 to September 8, 1883.
H. C. Shurtleff, Rodman, October 2 to December 11, 1883.
Benjamin Franklin, Rodman, July 17 to August 17, 1883.
E. S. Campbell, Rodman, August 20 to September 8, 1883.
G. A. Luccareni, Rodman, September 6 to October 31, 1883.
George W. Wood, Axman and Gauger, at Frederick, Montgomery county, June 4 to December 22, 1883; June 7 to December 20, 1884; May 1, 1885, to date.
J. G. Hillsman, Gauger at Forks of Neshaminy, June 30, 1883, to date.
R. C. Stover: Gauger at Point Pleasant, January 1, 1884, to date.
Ross Kirk, Chainman, July 9 to November 3, 1883.
Thomas Jamison, Chainman, June 5 to December 20, 1883;
June 10 to December 31, 1884.

Special Work.
Dana C. Barber, Sanitary Surveyor.
R. H. Sanders, Geologist.
Murray Rush, Appraiser.

Department Observers.
J. Kirk, Forks of Neshaminy, January 1 to May 14, 1884.
J. Wisler, Schwenksville, January 1 to May 1, 1884.
N. S. Renninger, Green Lane, July 24,1883, to April 1, 1884.
G. H. Hart, Pennsburg, September 9, 1883, to June 1, 1884.
G. W. Roth, Ottsville, September 1, 1883, to August 1, 1884.
Thomas H. Walton, Doylestown, October 5,1883, to December 31, 1885.
Dr. J. A. Roth, Seisholtzville, June 1, 1884, to date.
J. H.. Steltz, Green Lane, December 1, 1884, to December 31, 1885.
Edwin F. Heavner, Ottsville, August 1, 1884, to date.
[PAGE 307]
Dr. C. D. Fretz, Sellersville, May 24 to December 31, 1885.
H. L. Shull, Lansdale, May 1, 1884, to date.
George Lowder, Smith's Corner, January 15, 1886, to date.
Albert Stover, Point Pleasant, October 23 to December 31, 1885.

The Department is indebted to the following parties who have kindly furnished rainfall records:

General W. B. Hazen, Chief Signal Officer, Washington.
Serg. T. F. Townsend, U. S. Signal Service, Philadelphia.
Serg .C. H. Kitchel, U. S. Signal Service, Philadelphia.
Serg. L. M. Dey, U. S. Signal Service, Philadelphia.
Mr. E. F. Smith, Chief Engineer Canals, Reading, Pa.
Mr. Thomas Meehan, Germantown, Pa.
Pennsylvania Hospital, Philadelphia.
Mr. Thoman [sic] J. Beans, Moorestown, N. J.
Dr. Charles .Moore, Pottstown, Pa.
Mr. S. B. Lehman, Lebanon, Pa.
Milnor Gillingham, Fallsington, Pa.
Mr. M. McNeill, Princeton, N. J.
Mr. J. L. Heacock, Quakertown, Pa.
Miss Emily Kent, Phillipsburg, N. J.
Prof. S. J. Coffin, Easton, Pa.
Dr. J. C. Green, West Chester, Pa.

The Department is also indebted to the following gentlemen and corporations
for assistance rendered in lending maps, furnishing reports, etc.:

Prof. J. P. Leslie, Geologist, Pennsylvania.
Col. H. M. Robert, Corps of Engineers, U. S. A.
Pennsylvania Railroad Company.
Philadelphia and Reading Railroad Company.
Lehigh Valley Railroad Company.
Joseph S. Harris,. President Lehigh Coal and Navigation Company.
Prof. James Hall, Geologist, New York

[PAGE 308]

It is due to the members of the corps, and particularly to Mr. F. L. Paddock, Principal Assistant, to state that they displayed praiseworthy industry and skill, without which it would not have been possible to complete the investigation within the given time, nor for the available funds.


It remains now briefly to recapitulate the final conclusions that have been arrived at from the examinations described above. In making these investigations it has been taken for granted from the outset that the water from any point in the Schuylkill river, and from any point in the Delaware river below Trenton, will not be of a sufficiently good quality to furnish a future supply for the city, although the fact has been admitted that at present the Delaware water at Lardner's Point, within the city limits, is not only fairly good, but is likely to remain so for some time.

In looking about for an improved supply every practicable scheme was considered. No success could be expected from a supply by artesian or driven wells in this locality, nor would filtering or purifying the water of the Schuylkill or Lower Delaware give permanent satisfaction. The only schemes worth investigating were those which bring to the city the water of running streams in the Schuylkill, Delaware, or Lehigh watersheds.

It required but little thought to see that the water from the streams north of the Blue mountains would be the best available in quality not only now, but for an indefinite future, and that this region would therefore have to be the ultimate source of water supply for Philadelphia, and probably also for other cities lying between the mountains and the seaboard.

To obtain an intelligent opinion on the cost of such a supply, surveys and examinations were made which showed that. inasmuch as water of good quality can be secured at a less expense from nearer localities, it is not advisable at once to go to the Blue mountains. [PAGE 309] In adopting a scheme for an earlier future, this ultimate source, however, should be considered, so that the aqueducts now constructed could be available for the final source of supply. The quantity of water which it was thought best to calculate for at present was at least 200,000,000 gallons per day, or more than double the present consumption. The elevation at which the water should be delivered was fixed at about 170 feet above datum (the height of the present basin at Wentz's farm and the proposed basin at Cambria), because it gives the most favorable distribution for the city.

The streams offering a good water supply nearer than the Blue mountains are the Perkiomen creek, a tributary of the Schuylkill river, the Tohickon and Neshaminy creeks, tributaries of. the Delaware river, and the Delaware river itself, . above Trenton. In point of quality the water of the latter has been found to be the best; that of the Upper Perkiomen and Tohickon creeks comes next in quality; and that of the Neshaminy and Lower Perkiomen creeks is least good.

An estimate of the cost of obtaining Delaware water alone (Table 34) indicates that above Lardner's Point the most economical scheme is to bring it from Point Pleasant, as stated in the last report, because the river has quite a descent near this place, which materially reduces the height of pumping as compared with points lower down the river, such as Lumberville, New Hope, and Yardleyville. Another advantage gained by this sudden descent is the water power, which can be developed to furnish a daily supply of 120,000,000 gallons during the dry season.

The cost of the aqueduct, pumping plant, and capitalized cost of pumping amount to $19,622,543, if 210,000,000 gallons of water daily are pumped by steam, and to $15,475,262, if only 120,000,000 gallons are pumped by water and the remainder by steam.

Purely gravity supplies, without pumping (Table 35), can be obtained from either the Perkiomen creek or from the Tohickon [PAGE 310] and Neshaminy creeks combined. The latter project cannot be made to furnish a daily supply of over 156,000,000 gallons in years of minimum rainfall. While the water furnished by the Tohickon and Upper Perkiomen creeks is good, that which is taken from the Neshaminy and Lower Perkiomen, as already stated, will be of much inferior quality. Neither of these purely gravity schemes would therefore be quite satisfactory. The cost of procuring a supply from the Perkiomen creek is $13,674,493, and from the Tohickon and Neshaminy creeks together, $13,846,662.

Finally, a combined gravity and pumping scheme (Table 36) is possible by procuring water from the Tohickon creek and from the Delaware river at. Point Pleasant. The former can furnish on the average between 90,000,000 and 100,000,000 gallons per day by gravity; in minimum years only 80,000,000 gallons can be depended upon. The Delaware river, as we have seen, can furnish 120,000,000 gallons by water-power. Both the Tohickon and Delaware waters have been found not only to be of good quality, but much better than the waters of the Neshaminy, and particularly of the Lower Perkiomen creeks. The cost of this scheme is $12,695,941, if the water power is utilized, and $17,117,025, if steam-power is used.

It is therefore clear that the best and most economical project to supply the city of Philadelphia with water is to bring to it the Tohickon water by gravity, and to pump from the Delaware river, at Point Pleasant, by water-power.

In order to perceive the relative values of the different schemes with still more distinctness, I have made three estimates, one for completely filling the aqueduct, one for furnishing 150,000,000 gallons, and one for only 90,000,000 gallons per day (See Table 37).

To supply the latter quantity of water from the Perkiomen creek requires an expenditure of $10,495,000. In bringing [PAGE 311] 90,000,000 gallons daily from the Delaware watershed, it is found that the Neshaminy creek alone could furnish the amount, except during years of minimum rainfall, at a total expense of $7,875,000. The Tohickon creek also could furnish a quantity up to 90,000,000 gallons, except during very dry years, at a cost of $10,008,000. If the Delaware water at Point Pleasant is used, the cost for 90,000,000 gallons is $12,775.,000, if pumped by steam, and $9,673,000, if pumped by water-power. At Lardner's Point the cost would be $7,064,000.

Cost for delivering 90, 150, 210 million gallons daily.

[PAGE 312] Therefore, to supply the city with 90,000,000 gallons daily of good water, which is the present consumption, the cheapest project is to pump the Delaware water at Lardner's Point, the next is the Neshaminy scheme, and the third is pumping Delaware water at Point Pleasant.

To increase the supply to 150,000,000 gallons requires a total expenditure of about $12,139,000, if the Perkiomen water only is used, and a total expenditure of about $17,635,000, if no water is taken from below Green Lane, and the deficiency supplied from the eastern affluents of the Lehigh river above the Lehigh Gap.

On the Delaware areas the water stored from the Neshaminy and Tohickon creeks together could furnish an amount up to 156,000,000 gallons at a cost of $13,846,662. If, instead of using the Neshaminy water, Delaware water is pumped at Point Pleasant the cost would be $14,275,000, if steam, and $11,215,000, if water-power is employed. To supply Delaware water only would cost, if pumped by steam at Point Pleasant, $16,355,000, and at Lardner's Point, $10,415,000.

For supplying 150,000,000 gallons daily therefore from beyond Lardner's Point, the project contemplating the use both [PAGE 313] of the Tohickon and Delaware water at Point Pleasant, pumping the latter by water-power is the least expensive one.

Finally, to increase the supply to 210,000,000 gallons, the Point Pleasant scheme, as already stated, is again the most economical one, besides furnishing decidedly the best quality of water.

It therefore appears with sufficient clearness, I think, that whenever good water can no longer be obtained from Lardner's Point by the pumps which it may be considered advisable to place at this point, the city should build an aqueduct to Point Pleasant, pump Delaware water by water-power, and supplement the quantity as it may become necessary by storing the water from the Tohickon creek, first in the lower, and then the upper reservoir.

After the aqueduct is taxed to its full capacity, at which time it will probably be necessary to go to the Blue Mountains for an increased supply, another aqueduct will have to be built. It is premature, I think, to say definitely at present whether this second aqueduct extending to the Blue Mountains should go by way of the Delaware or Lehigh river. If the South Mountain region should preserve its present character, there can be no doubt that it should extend by way of the Perkiomen valley, and, after receiving the South Mountain water at Green Lane, follow up the Lehigh river. The cost of this scheme, which now is relatively greater than that of others, would then probably be less. The Point Pleasant aqueduct could later also be carried to the mountains whenever the quality of the water, owing to the pollution from the Lehigh river, becomes objectionable. And its extension would then most economically be to the Delaware Water Gap.

It is better to build two separate aqueducts in this way than only one with double the capacity, because in the latter case the risk from accident becomes greater. New York, Boston, Washington, and Paris have each two. London has even more.[PAGE 314] When the above-mentioned aqueducts are built the city of Philadelphia will be supplied with the best water obtainable in Eastern Pennsylvania.

Respectfully submitted,



October 26, 1886.
JOHN L. OGDEN, ESQ., Chief Engineer Water Department.

DEAR SIR :--Having heard that a proposition was to be urged recommending the diversion of the Tohickon water into the Perkiomen valley, and having considered this scheme over a year ago and rejected it, but failed to give the reasons for such rejection in my final report, I think it is proper that a note should be added. I enclose the same and beg you kindly to insert it at the place indicated and to consider it as a part of the report.

Had I not been so pressed for time and so anxious to get the report finished at the time promised, I should have reported on this scheme in greater detail.

Very truly yours,

[PAGE 315] NOTE.--After the topographical surveys of Bucks County had been plotted (during the spring of 1885) it became apparent to me that in addition to the various projects outlined in previous reports another one was feasible, namely, a diversion of the waters of the Tohickon creek, by means of a dam situated just below the mouth of the Haycock creek, through a comparatively short tunnel near Keelersville into the northeast branch of the Perkiomen. By this diversion it would be possible to substitute the Tohickon water for that of the West Swamp creek in the Lower Perkiomen scheme, which would not only improve the quality of water otherwise obtained, but also reduce the cost, as the inhabited territory between Green Lane and Schwenksville would not require to be flooded.

While I examined this scheme in a general way, I did not work it up in detail, for comparison with those that had been previously indicated for the following reasons: There were no features which promised superiority over the Delaware-Tohickon project. Inasmuch as the appropriation available for the investigation was barely enough to complete the same as originally outlined, it was therefore not considered advisable to extend it any farther. Such a course was thought proper, particularly on account of the marked disadvantages possessed by this project over the other one. The sewage and surface water from Quakertown could not be diverted from the city's supply, but might add pollution to the same. The Northeast Branch valley contains the two growing centres of population, Sellersville and Perkasie, which would still further add to the danger. In view of the constantly accumulating evidence that it is to a certain degree dangerous to have even small towns drain into a stream which subsequently requires impounding, this circumstance must be given considerable weight. The general physical characteristics of the Northeast Branch watershed are also inferior to those of the Tohickon, shown particularly in the heavy discoloration of its water after rains, so that the Tohickon water would be deteriorated by admixture with that of the Northeast Branch. The Tohickon water [PAGE 316] at Point Pleasant compares favorably with the water of the Upper Perkiomen, while if diverted, as above, it would be less good than at the Point, because it is deprived of considerable aeration which it gets in reaching the same, and of the excellent water received on its lower course through a rugged and sparsely populated region. Further, it is a well known fact that running water from large streams is healthier and generally more palatable than water which has been stored in reservoirs, and in this instance the large quantity of Delaware water which is available through the Point Pleasant project would furnish, as shown by the analysis, a much superior supply to that of any of the Lower Perkiomen affluents, even before storage. Finally, the estimated cost of the "diversion" as against that of the scheme recommended was not found to be in its favor.

Statistics of proposed collecting areas

Areas in acres of watersheds above gauging stations, subdivided according to their declivity, surface, characteristics, and elevations

Summary: Areas in square miles above gauging stations

Precipitation in inches at the Pennsylvania Hospital, Philadelphia, Pa., from 1825 to 1885, inclusive.

Maximum and minimum precipitation at Pennsylvania Hospital, Philadelphia, from 1826 to 1885, inclusive.

Monthly precipitation on sundry water-sheds, compared with U.S. Signal Service observations at Philadelphia.

Annual precipitation on sundry water-sheds, compared with U.S. Signal Service observations at Philadelphia.

Monthly yield of sundry streams

Yield of sundry streams in cubic feet per minute per square mile.
Ratios of average monthly flow in sundry streams.

Monthly precipitation on sundry watersheds, and percentages of same reaching the streams.

Available storage reservoirs

Flooded areas of available storage reservoirs

Estimate Cost of Storage Reservoirs
[Links range from 100-200 kb]
I. Tohickon Watershed
II. Neshaminy Watershed
III. Upper Perkiomen Watershed:
Reservoir 1, Reservoirs 2-7, Reservoirs 8-11, Reservoirs 12-15
IV. Lower Perkiomen Watershed:
Resevoirs 1-6, Reservoirs. 7-9

Storage capacity required to yield an average daily supply of 80 million gallons from Tohickon Creek.

Storage capacity required to yield an average daily supply of 101.3 million gallons from Neshaminy Creek.

Storage capacity required to yield an average daily supply of 52.8 million gallons from Perkiomen, at Green Lane

Storage capacity required to yield an average daily supply of 36.2 million gallons from East Swamp Creek.

Storage capacity required to yield an average daily supply of 151.2 million gallons from Perkiomen, above Schwenksville.

Storage capacity required to yield an average daily supply of 43.5 million gallons from North East Branch Creek.

Cost of Storage

Total cost of projects for a supply by pumping from the Delaware River.

Total cost of projects for a supply by gravity.

Total cost of projects for a supply, partly by gravity and partly by pumping.

Topographical map showing the watersheds of the
Perkiomen, Tohickon and Neshaminy Creeks,
from surveys made by the Phila. Water Dept. in 1883, 1884 & 1885
and from atlas published by the State Geol. Survey in 1883;
also available storage reservoirs, 1886

[129 kb]
Triangulation over parts of Bucks and Montgomery counties, 1885

Field Table [Photo-Collotype]

[281 kb]
Specimen copy of field sheet

[224 kb]
Topographical map of Tohickon Watershed near Point Pleasant, 1885. Specimen sheet from Section B.

Rain Gauge, one fifth size

Automatic gauge for recording maximum height of streams

Automatic rain gauge [Photo-Collotype]

Rainfall, 1886. Neshaminy and Tohickon series.

[161 kb]
Perkiomen measuring weir, above Green Lane

[202 kb]
Big Neshaminy measuring weir, At Warner's Ford

Automatic stream gauge and gauging weir, Tohickon Creek, at Point Pleasant [Photo-Collotype]

Automatic Stream Gauge [Photo-Collotype]

Stream flow, 1885, Tohickon Creek

[123 kb]

Chart showing the quantity of water in store at the end of each month from Jan. 1884 to Dec. 1885, inclusive, in proposed storage reservoirs in the Tohickon Valley, having a capacity of 3,349,778,000 cub. ft., the average daily withdrawal being 100 mill. gallons.

[121 kb]
Chart showing the quantity of water in store at the end of each month from Jan. 1884 to Dec. 1885, inclusive, in proposed storage reservoirs in the Neshaminy Valley, having a capacity of 3,135,914,000 cub. ft., the average daily withdrawal being 100 mill. gallons.

[124 kb]
Chart showing the quantity of water in store at the end of each month from Jan. 1884 to Dec. 1885, inclusive, in proposed storage reservoirs in the Perkiomen Valley above Green Lane, having a capacity of 3,089,854,000 cub. ft., the average daily withdrawal being 60 mill. gallons.

[98 kb]
Chart showing the quantity of water in store at the end of each month from Jan. 1884 to Dec. 1885, inclusive, in proposed storage reservoirs in the East Swamp and Rich Valleys, having a capacity of 1,595,808,000 cub. ft., the average daily withdrawal being 40 mill. gallons.

[194 kb]
Chart showing the quantity of water in store at the end of each month from Jan. 1884 to Dec. 1885, inclusive, in proposed storage reservoirs in the Perkiomen Valley above Schwenksville, having a capacity of 7,521,151,000 cub. ft., the average daily withdrawal being 150 mill. gallons.

[104 kb]
Chart showing the quantity of water in store at the end of each month from Jan. 1884 to Dec. 1885, inclusive, in proposed storage reservoirs in the N.E. Branch Valley, having a capacity of 1,896,000,000 cub. ft., the average daily withdrawal being 50 mill. gallons.

[379 kb]
Sundry comparative statistics of proposed collecting areas.

Automatic stream gauge and gauging bridge, Perkiomen Creek at Frederick.



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