trolled by the Commissioners of the District of Columbia, called the Fort Reno Reservoir, with a capacity of about 4,500,000 gallons, the reference of its water surface when the reservoir is full being about 420 feet. This reservoir is supplied with water taken from the supply mains by the U street pump.

The Dalecarlia and distributing reservoirs supply that part of the District which lies below 100 feet above datum. The areas lying between the levels of 100 and 210 feet above datum are supplied by pumping from the U street station directly into the distributing mains, the Georgetown high-service reservoir being held as a reserve supply. The areas having a greater elevation than 210 feet above datum are supplied from the Fort Reno Reservoir.

It will be observed, therefore, that the total present storage capacity of all reservoirs is a little less than 307,000,000 gallons, or about six days' normal supply.

Until the average daily consumption of water becomes considerably greater than at present, the reference of the surface of the water at the lowest stage of the Potomac will be about 151 feet at the mouth of the feeder at Great Falls, about 146.75 feet at the Dalecarlia Reservoir, and 146 feet at the distributing reservoir.

The total supply of water which the present conduit can safely furnish, without a pressure dangerous to its safety, is 76,000,000 gallons per diem. This, however, necessitates the lowering of the distributing reservoir to reference 144, thus involving a loss of head of 2 feet at that point of distribution.

The following statement shows the operations upon the aqueduct and its accessory works during the fiscal year, and their condition at its close:

GATEHOUSES, WATCHMEN'S QUARTERS, AND OTHER BUILDINGS.

The gatehouses and storehouses at the Dalecarlia and distributing reservoirs were covered with a wash of Portland cement and the iron and woodwork painted. The office was also painted.

The buildings at Great Falls were whitewashed and all necessary repairs for the proper preservation of these buildings were made.

THE RESERVOIRS.

A severe rainstorm on August 13 caused considerable damage at the Dalecarlia Reservoir. The rainfall between the hours of 11 a. m. and 8 p. m. was 5.44 inches. This heavy precipitation caused a rapid rise in Powder Mill Branch, Mill Creek, and East Creek.

The surface drainage which these streams collect is prevented from entering the Dalecarlia Reservoir by dams at their mouths. The water of East and Mill creeks and the surface drainage in the immediate vicinity of the reservoir are carried in a runaround channel and through a tunnel which empties the water into Powder Mill Creek above the dam, shutting off the latter from the reservoir, then by a shaft and tunnel into the spillway of the reservoir and so into the Potomac River.

The flood water of this storm reached its highest point at 6 p. m., attaining a height of 8 feet above the coping of the shaft of the main drainage tunnel and covering the bottom land of Powder Mill Branch for half a mile above the shaft to a depth of from 2 to 5 feet. The dam at Powder Mill Branch was uninjured, and remained 6 feet above the

flood level. The water, however, reached a stage of 6 inches above the Mill Creek Dam, and 3 inches above the dam on East Creek. The channels around the reservoir were overflowed, and the embankment of the 9-foot channel gave way for a distance of 45 feet at a weak spot and the smallest or 2-foot channel for a distance of 26 feet. The overflow of Mill Creek washed away the reservoir side of the dam for a distance of 280 feet, and a large deposit of gravel and sand was left above this dam and in the drainage channels. The damage to the work was repaired at once, repairs being completed by October 30. These repairs consisted in closing the break in the drainage channel, raising the Mill Creek dam 18 inches, the East Creek dam 1 foot, and the embankments of the drainage channels to heights corresponding to the new heights. of the dams.

The break in the drainage channel was repaired by placing at the weak part a concrete core in the embankment, the repairs to the dams and raising of the channel embankments being in earth work entirely. It is believed that this raising of the dams and embankments will prevent further overflow or breaks.

At the distributing reservoir 1,200 feet of new board fence was built, all old fences repaired, and daily observations of turbidity and level were taken at both reservoirs and at the influent at Great Falls.

During the year, except when the water was lowered for the purpose of measuring the daily consumption, the extreme fluctuation of level in the distributing reservoir was 1.50 feet.

The following table gives the fluctuation from and including the year 1894-95 to date, June 30, 1899:

This low level, 144.55, on February 16, was due to the severity of the weather, the thermometer reading as follows:

During such readings of the thermometer the household taps are, in a majority of cases, left running to prevent freezing, due to defective plumbing.

THE DAM AT GREAT FALLS.

The dam at Great Falls was repaired with 300 cubic yards of riprap backing. These repairs are necessary annually on account of the destruction of the riprap dam due to the passage of ice and flood débris over the dam.

Except for this slight damage, the dam remains intact and in perfect condition.

THE CONDUIT ROAD AND ITS FENCES.

For use in repairing the conduit road 600 cubic yards of stone were crushed and spread on the road near the Dalecarlia Reservoir. General repairs were made to all portions of the road, ditches were cleaned, bushes cut down, slopes trimmed, deposits removed from the culverts, and four small road culverts were constructed.

There were purchased 3,116 cubic yards of flint stone for macadamizing and repairing the conduit road. Eleven thousand five hundred and twenty feet of guard fence were built on the embankments, the old guard fences were repaired, and all fences whitewashed.

It has been customary to submit an annual estimate for the repair of the conduit road.

As the keeping of this road in proper order is a necessary item in the repair and maintenance of the Washington Aqueduct as long as it is kept open to public traffic, it is not deemed necessary to submit a special estimate for this purpose. The road is essentially a part of the aqueduct system, and the expense of improving it and keeping it in order would seem a proper charge to the improvement, maintenance, and repair of the Washington Aqueduct.

THE MAINS.

The trunk mains, aggregating 21 miles in length, which lead from the distributing reservoir and supply the distributing system of street mains, were laid by the United States and are under the control of this office, but the distributing mains were laid by the city of Washington and the District of Columbia, and are under the care and control of the Commissioners of the District.

A break occurred in the 24-inch main at Tenth and K streets northeast on October 23, 1898, and was repaired in seventeen hours.

Several leaks in joints of the 48-inch main on M street and a leaky joint in the 30-inch main at the intersection of New Jersey and Massachusetts avenues were repaired by calking.

The 30-inch main at the intersection of New Jersey and Massachusetts avenues, which was so near the surface as to interfere with the changing of the electric railway at this point to the underground trolley system, was lowered for a length of 230 feet from 0 at the ends to 30 inches at the mid-length joint. The work of lowering was conducted. under the supervision of this office but at the expense of the railway company.

Twenty inch connection was made with the 48-inch main at Seventeenth and R streets northwest by the District Commissioners for the purpose of increasing the supply at the U-street pumping station.

THE BRIDGES.

All the bridges are now in excellent condition. The iron bridge sup porting the 48-inch main across Rock Creek was painted and small repairs were made to the Pennsylvania Avenue Bridge and Dalecarlia Reservoir Bridge.

The roadway of Pennsylvania avenue, which in the vicinity is 53.5 feet in clear width, is contracted on the bridge to a clear width of but 17 feet, and as drivers are required to walk their teams while passing over the bridge, a congestion of travel results during the busiest hours of the day, causing delay and annoyance, as there is not room for one

team to pass another, and consequently the speed of all teams on the bridge moving in the same direction is limited by that of the team in front. Especially is this annoyance felt by the thousands of bicycle riders who daily pass over the bridge and who, unless experienced riders, are frequently forced to dismount and lead their bicycles over the bridge, the rate of progress of the teams blocking the roadway ahead being too slow to allow an inexperienced rider to maintain equilibrium. In addition, the sightly appearance of the avenue is much injured by the extreme contraction at this point.

This bridge, the property of the Washington Aqueduct, is very graceful in appearance and is unique among the bridges of the world, in that the roadway is supported upon arched ribs formed by two 48-inch cast-iron pipes, through which flows at least half of the water consumed by the city. It would seem, therefore, that any plan to widen the bridge should preserve both the graceful form and the distinctive features of the bridge.

A board of engineers, constituted by Special Orders, No. 8, February 2, 1877, and composed of the following officers of the United States. Corps of Engineers, Bvt. Maj. Gen. Z. B. Tower, Bvt. Maj. Gen. H. G. Wright, and Bvt. Maj. Gen. Q. A. Gillmore, was assembled to examine into the propriety of certain proposed modifications of this bridge. This board, after due consideration of the matter, reported as follows:

It would, in our opinion, therefore, better accord with the position on Pennsylvania avenue and with the general character and architectural effect of other aqueduct structures to widen this structure, without changing its design, by the addition of two arched iron ribs similar to those of the present bridge and by widening the abutments.

These two arched ribs should be made about as heavy as those of the present bridge. As the previous discussion shows the latter to be abundantly strong without the truss work, in the new construction the greater portion of the whole weight of the bridge could be thrown upon the added arches not used as water pipes.

We regard the arch as far more sightly, beautiful, and architectural than the truss, and therefore more suitable for this position.

On April 26, 1877, the late Gen. Thomas L. Casey, United States Corps of Engineers (retired), then in charge of the Washington Aqueduct, was requested by the Chief of Engineers to investigate and report upon "the present and prospective use of that bridge as a highway, etc." This he did on July 19, 1877, his report concluding with the following opinion:

I am further of opinion that the present and prospective interests of the citizens of Washington and Georgetown do demand an increase in the width of the roadway and of the footways, the present width being, of the roadway only 17 feet, and of the footways 4 feet each.

The abundant strength and stiffness of the present bridge, under any statical or moving loads that are likely to be placed upon it, are clearly shown by the investigations of the board of engineers, as detailed in its report of April 7, 1877, and I agree with it as to the manner in which the widening of the road and footways should be accomplished, should it be decided to increase their width, namely, by the addition of two arched iron ribs, similar to those of the present bridge, and by widening the abutments. The estimated cost of widening the bridge in the manner above stated is $75,000.

While it is believed that the interest and convenience of the citizens of Washington and Georgetown demand the widening of this bridge, yet because the present structure amply suffices for all requirements of the Washington Aqueduct system, and because during the past few years no official complaints regarding the width of the bridge have been made to this office, no estimate is submitted for this work, the

estimates for the next fiscal year being confined to those subjects directly affecting the operation of the Washington Aqueduct.

THE TELEPHONE LINE.

Small repairs have been necessary to maintain the line in excellent condition.

CONSUMPTION AND WASTE OF WATER.

Measurements of the daily and hourly consumption and waste of water were made on June 21, 22, 1899, and detailed record of the measurements is given in the following table:

Measurements of the daily and hourly consumption and waste of water.

[Hourly and total flow from the distributing reservoir for twenty-four hours, ending at 6 a. m.]

Average daily consumption and waste of water in the city, as measured annually in the latter part of June of each year, from 1874 to 1899, both inclusive.

From the above table it will be observed that the consumption and waste of water in the District of Columbia for June 21, 1899, was 50,079,855 gallons per diem. This is the largest June measurement ever