Public Works, The Passano Files

Conduit: Druid Lake and the Wall of Mud (1863 – 1871)


A lithograph of Druid Lake made by A. Hoen and Company as part of their Baltimore City Water Works series. Druid Lake, A. Hoen, ca. 1880, MdHS, H264.4

In 1863 the Baltimore City Council approved a $300,000 loan to construct a billion gallon capacity reservoir in the newly established Druid Hill Park. Though the new city waterworks project from Lake Roland to the Mount Royal Reservoir on the Jones Falls had just been completed, it had become apparent that the city’s water problems were far from solved. Having an abundance of natural springs and deep ravines, Druid Park seemed to be the perfect site for a new reservoir. In addition to providing suitable drinking water, this reservoir was also meant to enhance the beauty of the newly created park, accompanying its ancient oak trees bearing noble names such as “The Sentinel,” “King of the Forrest,” and “Tent Oak.”


A map of Druid Hill Park showing Mount Royal Reservoir is located in the top right, Druid Lake in the center, and the High Service Reservoir on the bottom left. The map is rotated facing northeast. Druid Hill Park, Board of Park Commissioners, 1875, MdHS, M79

Stressing the need for clean air and open space to buffer Baltimoreans from “the noise of the hammer and the smoke of the furnace,” Mayor Thomas Swann (1809-1883) decided to employ a rather innovative source of funding to provide open space for citizens without increasing their tax burden. In 1860 Swann passed Ordinance 44 which would award a highly competitive contract to a horse drawn passenger railway providing the company give twenty percent of its gross income to the city for the purpose of providing open space.*

After responding to an advertisement placed in local papers by the Park Commission seeking to buy a large plot of land for a public open space, Lloyd Nicholas Rogers (1787- 1860) sold the Druid Hill estate for $121,000 in cash and $363,027 in city stock. Though the cantankerous Rogers tried to back out of the deal late, claiming the city lacked the authority to issue bonds outside the official city limits for the purchase, Mayor Swann, in one of his many questionable abuses of power, got the deal pushed through.

Perhaps Mayor Swann saw the writing on the wall concerning the city’s water supply issues, when during the Druid Hill Park inauguration ceremonies he stated that:

“…In addition to numerous springs heading in all the principal ravines, and furnishing a liberal supply of water for ordinary wants, the close proximity to the Jones’ Falls, and the great receiving reservoir of the city, gives assurance that the most extensive arrangements may be safely made for the lakes and fountains at a comparatively trifling expenditure. A resort to artificial supply is always to be preferred in a park, where the volume of water cannot be relied upon from natural flow….[Then upping his flowery poetic waxings, continued]…the soft and trembling shadows of the surrounding trees and hills as they fall upon a placid sheet of water, and the brilliant light which the crystal surface reflects in pure sunshine, mirroring too, at times, in its resplendent bosom, all the cerulean depth and sunny whiteness of the overhanging sky, give it almost a magical effect in a beautiful landscape.”

In 1864 the city began to utilize the natural geography of Druid Park as they made their “cerulean” vision a reality. A deep ravine formed by a stream that traveled southeast from the boat lake toward the Jones Falls was selected as the site for the new reservoir. Civil engineer Robert Martin developed plans and  constructed a giant wall of mud that became the largest earthen dam in America (at that time). Steam excavators were used for the first time in the city to move 500,000 cubic yards of earth. The dam itself consisted of a water tight clay core, or puddle wall,  surrounded by steep banks of soil, and was supported by a stone wall laid in cement running the entire length of the dam. Earthen banks were laid in thin layers and pressed by horse drawn rollers. When completed in 1871, the dam supported a reservoir that covered 55 acres, reached a depth of 94 feet (averaging 30 feet), and sat at an elevation 217 feet above mid-tide. Towering over the surrounding park at a height of 119 feet, the dam was 750 feet long, with a width of 600 feet at the base tapering up to 60 feet at the top.


The embankment and gate house at Druid Park from the Baltimore Water Works series. Baltimore – Reservoirs – Druid Lake – 1880 – MdHS, SVF (medium photo)

In 1864 work started on the reservoir, and by 1865, seven 30-inch pipes were taking water in and out of the reservoir: three from Hampden, three to Mt. Royal, and a drain pipe. Things didn’t necessarily go smoothly…

The year work on the dam began in Baltimore, the whole world read about the horror of the Dale Dyke reservoir in Sheffield England, where flooding from the spring thaw caused the dam to fail. Eight hundred and fifty-five million gallons of water rushed through the valley at 18 mph, killing 244 people. The public saw eerie similarities between the earthen dam in England and the new dam in Druid Park. Though Dale Dyke was at a higher elevation, the new reservoir in Baltimore was in much closer proximity to the population center and held a greater amount of water. In addition, when water was drawn off from the reservoir in 1866, it was confirmed that the seven pipes traveling through the base of the earthen dam had buckled and collapsed under its weight. The broken pipes at the bottom of the dam posed the risk of significant leakage that would compromise the integrity of the earthen structure. It appeared that a complete overhaul of the dam was necessary.


A. Hoen and Co. lithograph of the earthen dam and gate house, most likely modeled after the photograph above. Embankment and Gate House, Druid Lake, A. Hoen, ca. 1880, MdHS, H264.8

A board of experts consisting of engineers Isaac Ridgeway Trimble (1802-1888), Charles Pratt Manning (1817-1886), and John H. Tegmyer (1822-1901) were appointed by the city to see if the new dam in Baltimore posed a similar risk to the catastrophe in England. The board concluded that they saw the “impossibility of failure from anything like similar causes” because the puddle wall had been constructed properly and the banks had been sufficiently compacted. Most importantly, the board proposed to replace the seven broken pipes with five new mains enveloped in stone arches that would not penetrate the puddle wall, exiting through the south side of the dam. Over 140 years later the dam has continued to hold strong, and in 1971 it was named a National Historic Civil Engineering landmark by the American Society of Civil Engineers.

Ultimately $1,000,000 was spent to repair the cracked pipes, and the reservoir was reduced to holding only 429 million gallons of water (as opposed to the initial goal of one billion). By 1871 Druid Lake was complete.** Over the next four years a west high service reservoir was added at a height of 320 feet above mean tide to service areas at higher elevations in the northwest part of town. By 1872, faced with more serious droughts, the city once again realized its supply of water was not sufficient, and finally turned its eyes towards the Gunpowder. Ironically, the $700,000 difference between the projected cost and the cost after the repairs was almost identical to that saved by selecting the waterworks on Jones Falls over the much higher volume project on the Gunpowder River. (Eben Dennis)

Ephemera- Series E- City Government-MdHS

Gunpowder Water Supply, no date, MdHS Ephemera – Series E – City Government

* The “park tax,” as it was known, would dwindle to 12 percent in 1874, 9 percent in 1882, 3 percent in 1932, then disappear completely.

**The resulting body of water had been known during the first half of its construction as Lake Chapman, after Unionist Mayor and head of the Water Board at the time, John Lee Chapman (1811-1880). Since much of Chapman’s tenure as mayor was characterized by the bitter partisan feuding of the Civil War period, it came as little surprise when his Democratic successor, Robert T. Banks (1822-1901), and the City Council voted unanimously to change the name to Druid Lake just four months after he left office in early 1868.


Bowditch, Eden and Draddy, Anne. Druid Hill Park : the Heart of Baltimore (Charleston, SC: History Press, 2008.)

Cox, J. Journal Proceedings of the First Branch City Council of Baltimore (Baltimore, 1866.)

Coyle, Wilbur F. The Mayors of Baltimore (Baltimore, MD : reprinted from the Baltimore Municpal Journal, 1919.)

Hall, Clayton Coleman. Baltimore: Its History and Its Peoples (New York:  Lewis Historical Publishing Co., 1912.)

Howard, William Travis. Public Health Administration and the Natural History of Disease in Baltimore, 1797-1920 (Washington, DC: Carnegie Institution, 1924.)

Inauguration Ceremonies and Address of Hon. Thomas Swann on the Opening of Druid Hill Park, October 19, 1860 (Baltimore, Md: Bull and Tuttle, 1860.)

Passano File, H. Furlong Baldwin Library, Maryland Historical Society.

Scharf, J. Thomas. History of Baltimore City and County (Baltimore, MD: Regional Publishing Company, 1971.)

Weishampel, Jr., J.F.. The Stranger in Baltimore: A New Hand Book, Containing Sketches of the Early History and Present Condition of Baltimore, with a Description of Its Notable Localities, and Other Information (Baltimore, 1866.)

“The Park.” Baltimore Sun, June 16, 1860.

“Mayor’s Message.” Baltimore Sun, January 5, 1865.

“Local Matters.” Baltimore Sun, January 18, 1865.

“Local Matters.” Baltimore Sun, March 4, 1865.

“Local Matters.” Baltimore Sun, November 5, 1867.

“Committe on Water Investigate the Circumstances….” Baltimore Sun, November 12, 1867.

“Local Matters.” Baltimore Sun, March 18, 1868.

“Baltimore Water Supply.” Baltimore Sun, August 25, 1869.

Baltimore City Services History



One thought on “Conduit: Druid Lake and the Wall of Mud (1863 – 1871)

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