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 of the RIDEAU  Tales' HomeOliver's FerryWatson's MillGhosts of KilmarnockGrand Non-OpeningLost Barrel of SilverOpinicon GhostsLady in BlueChristmas 1826A Rapid RideBlue Edged BowlsWashed AwayThe Last DuelDavidson's GhostA Rock for DinnerSluiced SuperintendentThe Failed GatesA Grave RevealingBye ByThe Lake Lock |
by Ken W. Watson
Why is there a lock in the middle of a lake? Locks are normally situated at navigation impediments such as rapids, but such is not the case with Narrows Lock, situated in the middle of Rideau Lake. It’s a story of disease and geology.  The original plan for this area of the Rideau Canal, which Lt. Colonel John By, R.E., Superintending Engineer for the Rideau project proposed in 1827, was to construct a dam and two locks at Chaffey’s Mills, an open canal cut across the Isthmus (the main watershed divide between the Rideau River Watershed to the north and the Gananoque River and Cataraqui River watersheds to the south) at Newboro, and a dam and one lock at First Rapids (Poonamalie). Based on the original surveys, the dam and lock at First Rapids would raise the level of Rideau Lake by about 3 feet (0.9 m) and the dam and locks at Chaffeys would raise about 18 feet to match that level. This would create a very large summit pond, 46 km (28.6 mi) in length able to supply water to both sides (Cataraqui/Gananoque watersheds and Rideau River watershed) of the Rideau Canal.
By 1829, By was in trouble with his original plans. Two issues had come to the fore to thwart his original design. One was malaria, which, with complications from other diseases of the day, played havoc with the workers each summer, particularly in the southern Rideau. Newboro was one of the hardest hit areas. Malaria first struck the work camps in the summer of 1828. Endemic within the range of the Anopheles mosquito in Ontario since the late 1700s, the Rideau work camps provided ideal conditions for the mosquito to spread the disease. Annually about 60% of the workforce would come down with the disease and 2 to 4% would die. The only “hard” numbers we have for Newboro are for 1830 when 70% of workforce contracted malaria (234 men) and 4% (14) men died. Its main effect was to put fear into all the men and by 1829, men were disappearing from the sites during the “sickly season” (August to mid-September) in order to avoid getting sick. Those that were willing to stay demanded higher wages. The second issue was the geology of the Isthmus. When surveyed in 1823/24 by Samuel Clowes and in 1827 by John MacTaggart and John Burrows, the presence of hard bedrock was not noted. A hard rock known as migmatite underlies this area. Migmatite is a product of high temperature melting, a cross between an igneous rock and a metamorphic rock. The bottom line is that it is very hard – and given the blasting technology of the day (black powder), it was very difficult to excavate. In a report written by John MacTaggart to Colonel By in 1828, he writes “The oftener I examine the excavation now in progress between Rideau Lake and Mud Lake the more I am convinced that it is going to turn out to be a more difficult piece of work than has been suspected.- ...I am sorry that when surveying this Isthmus last Summer we had not a set of boring tools to ascertain its nature more fully in consequence the estimate returned of this work will not I am afraid be sufficient unless some other method than the present be adopted. ...” (Price pg.244). In addition, the rock was fractured, so as they dug down, water flowed into the works. Pumping out this water was a slow and laborious process. In October 1828, the contractor for this site, William Hartwell wrote to Colonel By, asking to be released from his contract: “From the nature of the Rock on my job, I now find from what I have expended, say to the amount of two thousand pounds, exclusive of what I have received from you that it is totally out of my power to fulfil my engagement at the Contract prices-under those Circumstances and from your knowledge of the nature of the rock, may I request you will take my Situation into your Consideration, and release me and my Securities from the Contract; by so doing you will much oblige.” (Price pg.244) By was in a dilemma. He wasn’t impressed with Hartwell’s progress and so released Harwell from his contract. Another contractor , a Mr. Stevenson was hired. But Stevenson wasn’t able to attract any labourers at the going rates and soon quit the job. By needed a new solution and his first action was to take control of the job himself. He put Capt. Cole directly in charge of the work at the Isthmus and raised the labour rates in order to attract a workforce. In addition “to induce Labourers who were dispirited from the place having been so extremely unhealthy in the year 1828 to return, I have accommodations built for them, and Provisions of every description provided for their Comfort, …” (Price pg.250) But by 1829, By was again in trouble with this part of the Rideau project. The hard fractured bedrock at the Isthmus was giving him nothing but headaches. There was no way he was going to complete this section in time. So he looked a for a new solution. The one he came up with is deceptively simple; if you can’t dig down, then bring the water up. But how much could he raise the water level? New detailed surveys of the lakes showed him that he could raise the level in the area of today’s Upper Rideau Lake by almost 5 feet. By was initially looking to raise the water only 4 feet, so this plan seemed do-able. The easist solution would have been to add that 4 feet to the total lift at Chaffeys and at Poonamalie but this wasn't the route that By chose to go. The records are a little unclear on the exact chronology of the decision making. At some point prior to 1830, By had decided to go from two locks at Chaffey’s to one lock stating: “Prior to commencing the Works I directed further Levels to be taken when it was ascertained that by Deepening the Bed of the River, and cutting off some Rocky points, the Rise to be surmounted might be reduced to 12 feet 6 inches, I therefore considered, that by constructing a Waste Weir in such a manner as would enable the Water in the Lakes to be duly regulated, two Locks would not be required but that one of 12-1/2 feet Lift might be placed in the Channel of the River with perfect security.” (Price pg.258) It appears that by the time By was wrestling with the problem of bedrock at the Isthmus, his one lock plan for Chaffeys was already in progress. So adding 4 feet at Chaffeys would make for a higher dam and higher lock gates. By felt that this extra height couldn’t be done with safety. His second issue was that adding 4 feet at both Chaffeys and Poonamalie would flood a great deal of extra land in the areas of Lower Rideau Lake and Newboro Lake, land that would have to be compensated for. But, given that the western end of Rideau Lake could be flooded by that amount without causing undue damage, he decided that the best course of action was to put a lock at the bottom end of the Isthmus cut and at a narrow section of Rideau Lake known as Upper Narrows (today’s Narrows). This placement of two locks would raise the level of the existing Rideau Lake in that location, creating what we know today as Upper Rideau Lake. “I considered it indispensably necessary to deviate from the original plan, and have therefore backed up 4 feet of water by placing a Lock and Dam at the Narrows, and to surmount this additional rise, it being impracticable to raise the water of Mud Lake by increasing the lift at Chaffey's Mills with safety, a Lock of 4 feet lift, is placed at the end of the Excavation at the Isthmus, entering Mud Lake” (Price pg. 251).
It’s interesting to note in the records that one of the Royal Engineers working with Colonel By, Lt. Edward Frome, disagreed with him. There are no records of discussions between Frome and By at the time, but in an 1837 report Frome wrote “Had the Mud Lake been raised to the same level as the Upper Rideau, by placing this lock as an addition to that at Chaffey's Mills, and the lift of 4 feet 10 inches of the Narrows added to that of 6 feet 4 inches at the First Rapids [Poonamalie], the summit level would have extended the whole distance between this place and Chaffey's Mills, about 30 miles, and the work at the Narrows have been reduced to merely deepening the old channel, or making a short cut across the tongue of land. Some low ground must of course have been flooded by this plan, both on the shores of the Lower Rideau and Mud Lakes, but it is of little value, when compared with the saving it would have occasioned.” (Price pg.254).
By did envision that his plan might be changed in the future, but not by raising the water at Chaffeys and Poonamalie, but by deepening the cut at Newboro. To this end he built the locks both at Newboro and at Narrows without breastworks (upper foundations). This would allow them to be easily converted into guard locks (non-lift locks). “And should it be found advisable at any further period, on the Country becoming more healthy, to deepen the said Excavation, as originally proposed, it can be done, and there being no Breast Works to the Two Locks above mentioned they will then Serve as Guard Locks.” (Price pg. 249). Although the cut at Newboro has been deepened over the years, the area has never reverted to By’s original plan of having an open waterway between Chaffeys and Poonamalie. The only other change in the area is that over the years, the height of the dam at Poonmalie has been raised, reducing the lift at Narrows from about 4.8 feet (1.5m) in 1832 to 2.5 feet (0.8) m today. So, now you know why there is a lock in the middle of a lake. Narrows, the “Lake Lock” continues to operate today – the dam and weir at this location maintaining the level of Upper Rideau Lake. It’s a testament to Colonel By’s skill at adaptive engineering – coming up with a unique, very successful solution to a problem brought on by disease and geology. 
Sources: Malaria Info: Malaria Mythconceptions and Malaria on the Rideau Price, Karen, "Construction History of the Rideau Canal," Manuscript Report 193, Parks Canada, Ottawa, 1976.
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Comments: send me email: Ken Watson
