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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 LockThe Wall of Water |
by Ken W. Watson It was April 1832 and Daniel Ansley had a problem. His sawmill, located at the outlet of Loughborough Lake, wasn’t working as it should. The fluctuating levels of water in the lake meant that more often than not, there wasn’t a sufficient head of water to keep his water wheel turning. The mill, which Daniel and his father Amos had built here in 1816, was getting old, repairs had reduced the efficiency of the water wheel and milling machinery. During spring runoff there was lots of water and no problems, his sawmill was able to operate at full capacity. But dropping levels meant that soon, there wouldn’t be enough water to turn the wheel and power the saws. He needed to impound more water. His father Amos had passed away in 1830 and Daniel was on his own to run the mill.
As Daniel was pondering a solution, Lt. Colonel John By was preparing for his inaugural trip through the newly completed Rideau Canal. Finishing touches were still being done, but now, with the ice about to break, it was soon going to be time for the first triumphant cruise. The trip was originally going to be done with Robert Drummond’s brand new 110 foot long steamship the “John By.” According to the design, it was supposed to draw only 3.5 feet of water, but, when launched, it drew over 6 feet of water, too deep a draught to travel the Rideau Canal. However, Drummond was a resourceful man and he assured Colonel By that a vessel would be ready by mid-May for the big trip. Drummond’s 80 foot long vessel “Pumper,” which Drummond was using to pump water from behind the coffer dam at the lower lock at Kingston Mills, was in fact a steam ship. Its 12 hp steam engine, powering the two side paddles, could move the boat along at a reasonable clip. Drummond quickly had it re-fitted it for the historic voyage, even temporarily renaming it “Rideau,” a more fitting name for this historic voyage. Daniel stared at his timber mill dam for the umpteenth time. Two possible solutions, to re-build the mill dam higher, or located the mill further downstream, were huge undertakings. He needed a quick solution, the ice was about to break and spring runoff would be raising the level of the lake. Then inspiration struck. It was a technique he had heard about, the addition of flash boards. These were horizontal planks, placed upright on the top of the dam to increase the height of the dam. He could do the work on his own – it wouldn’t take long. Robert Drummond prepared Pumper for the inaugural voyage. He filled it with supplies for the journey, outfitted the cabin for the comfort of Colonel By, his wife Esther By and their two daughters, Esther and Harriet. Drummond even managed to mount a small canon to the front the vessel – this would be used to announce Colonel By’s arrival at each lockstation and community on the voyage to Bytown. It would be a grand trip. Back at Loughborough Lake, Daniel was busy implementing his plan. He pounded upright timbers into the top of his dam, securing them with timber back bracing. Then, taking discarded planks and slabs from his mill, he fastened these against the timber uprights. From the dam’s location (present day Battersea), Loughborough Lake stretched 5 miles (8 km) north and 11 miles (17 km) south. Every foot of water that would rise against these boards represented millions of gallons of extra water, enough to run his mill for weeks. He repositioned his flume to take full advantage of the greater head of water. The job done, Daniel sat back and waited for the water to rise. It was May 23 and with great fanfare, Colonel By and family boarded the newly christened Rideau. With a full head of steam, side paddles churning, it left Kingston Harbour and started up the Cataraqui River. The procession of boats was led by the dockyard cutter Snake. In the rear, attached to the Rideau with tow lines were two barges, one containing the band of the 66th Regiment. Several hours later the entire procession passed through the locks at Upper Brewers, through the rocky constriction at the Round Tail and into Cranberry Lake. The lake was, to coin Colonel By, a “fine sheet of still water”, at full navigation depth due to the canal dams at Upper Brewers and at White Fish Falls (Morton). A coffer dam was still present in front of the weir at Upper Brewers – the final touches were being put on the weir to make it fully operational. As Colonel By’s flotilla passed into Cranberry Lake, some 4 miles (6 km) as the crow flies to the west, Ansley’s temporary dam additions started to creak rather ominously. The dam's location, at the eastern outlet of Loughborough Lake, was one of the headwaters of the Cataraqui River. The outflow from the dam went by a meandering creek into a much expanded Dog Lake and then into an expanded Cranberry Lake, the original channel of the Cataraqui River now drowned beneath the canal dam raised waters of these lakes. The flotilla continued north. The Snake and barges would only go as far as Jones Falls before returning to Kingston. The Rideau would continue triumphantly to Bytown, marking the official opening of the Rideau Canal. Daniel was getting worried, his flash boards were taking a lot of pressure since Loughborough Lake had risen an additional two feet. He could see the uprights supporting the boards starting to bend back – leaks were starting to appear. He opened the flume up to full capacity, yet still the lake continued to rise, putting more pressure on the additions to the dam. He realized the dam was in a dangerous state but he didn’t dare risk going out on top of it to try to reinforce it. He considered taking a boat to the northern outlet of the lake to remove the dam he’d erected there several years ago to block that outflow. But it was of solid construction, it would be very difficult to take apart. It didn't matter, it was already too late, no course of action would prevent the oncoming event. It was a lovely morning at Upper Brewers. The construction crews had the day off a couple of days before to view and cheer the procession of boats that passed though the locks and witness Colonel By waving to the assembled crowd. But now it was back to work as normal, putting the finishing touches on the site. Some of the iron work had cracked on the locks during this first passage and that had to be repaired. But more importantly, the weir had to be completed. A coffer dam and bypass channel ahead of the weir kept it clear of water as the stop log lifting mechanisms were put into place. The work was almost done.
The foreman on the job was standing on the canal dam, watching his men work on the weir. He wiped his brow and looked up channel. It was a clear, calm day – but now he hear a strange sound - like a distant rushing wind. He’d never heard anything quite like it. The sound seemed to be coming from the north, but he couldn’t place it. The view up channel didn’t seem quite right, but it took him a few moments for his brain to process exactly what he was seeing. His eyes widened as he realized he was looking at a wall of rushing water. “Run” he cried, turning to the men working on the weir. “Get to high ground” The men, used to obeying the foreman’s orders, immediately ran for the hills. Their decision making was helped by the sight of the foreman, running for all he was worth along the top of the dam towards the knoll that overlooked the locks. The foreman had scrambled partway up the knoll when he turned to see the first rush of water crash into the coffer dam. For a few seconds he thought it might hold, but then with the screech of splitting timber, the force of the water carried it away. Water mixed with coffer dam timber crashed into the weir. Although the main force of the wave was blunted, the water continued to rise and now sloshed its way through the new side channel on its way to the locks. The foreman turned and ran to the top of the hill in time to see the floodwaters hit the gate. He gave a sigh of relief as the gate held. But the next worry now was the rising water, would it breach the lock itself? Water overflowing a lock would quickly erode out the sides. Although the lock had been built with almost a 4 foot flood guard (height of the lock wall above normal water level), it wasn’t designed for this type of rapid rise. For a few minutes it looked like the foreman’s worst fears were about the happen. The water rose to the top rail of the lock gate which was about a foot below the elevation of the lock wall and started to spill into the lock. Then, still rising, it started to flow over the berm beside the basin. There was nothing that could be done. He looked around, everyone was now on high ground. He felt his heart pounding a mile a minute from the recent excitement and his anxiety that the lock might fail. But now, as he watched, the water level stopped to rise. In fact it looked like it was slowly starting to go down. The water over the lock gate slowed to a trickle and then the level dropped below the height of the gate. He ran over to the other side of the knoll and looked down. The open weir, now with coffer dam logs jammed in it, was doing what it was designed to do – carry away surplus water. Water was roaring through the weir, but the weir structure itself was holding up just fine. It had been designed to accommodate flood water and now it was doing just that. The foreman started a count of his men. In the end no one was hurt, not even a scratch. They had been lucky. There were only two possible sources for the floodwaters – a canal dam breach at Jones Falls, unlikely since that solidly constructed stone dam had been completed the previous fall, or a mill dam breach at Ansley’s Mills. By noon the water levels had stabilized enough that he could send men in canoes to investigate both posibilities. A few hours later he got word back that it was the Ansley mill dam that had failed. He wrote up a report of the incident and sent it by canoe directly to Bytown. His boss, Robert Drummond and the supervising Royal Engineer, Lieutenant Briscoe, were both with Lt. Col. By on the inaugural voyage aboard the Rideau. At the time of this incident, the Rideau was still steaming towards Bytown, it arrived there on May 29, about the same time the report of the incident at Upper Brewers caught up with it. Daniel stared at his ruined dam. When the first of the flash boards failed all hell broke loose. The force of the rushing water ripped out the remaining flash boards and opened up a considerable breach in the dam. For awhile it looked like all of Loughborough Lake was going to drain to the Cataraqui River. Preoccupied with the ruins of his dam and significant damage to his mill, he didn’t give much thought to the effect all his lost water was having on the brand new Rideau Canal lockstation downstream from his dam. When Colonel By received word of this incident, he sat down and penned the following letter, dated May 30, 1832, to his commanding officer, Colonel Nicolls: I have the honor to report for the information of the Master General and Right Hon'ble & Hon'ble Board, that a few days since, a temporary dam broke away which was improperly erected by a private Individual at Ansley's Mills on the South East outlet from Lough'borough Lake, and was formed of rough boards and Slabs, intended to Keep a head of Water on the Lake about two feet higher than the original Saw Mill Dam - this Lake contains from 16 to 18 Square Miles, and is about 19 feet above the level of the Rideau Lake - consequently, when this temporary Dam gave way, the whole of the water, so raised, rushed into Cranberry Marsh, and caused a greater pressure on the embankments and Gates at Brewers Upper Mills, than could have been anticipated, but, fortunately, did little or no injury, except that of carrying away the Coffer Dam in front of the Works at Brewers Upper Mills. To prevent the damage that might arise to the Works by the recurrence of a similar accident, I have taken upon myself the responsibility of directing that a safety Gate be constructed at Brewers Upper Mills, agreeably to the Enclosed Plan, the expense of which shall, be reported as soon as ascertained, and I trust that the whole of the Canal will again be open to the public in the course of 18 or 20 days.Presumably By had already given some thought to the idea of a safety gate, his enclosed diagram was designed for emplacement in the rocky constriction just upstream of the basin at Upper Brewers. This gate would lie flat on the bottom of the channel and then either be raised manually or swing up with high water flow such as a flood. Once upright it would block the channel. It was one of only two ever installed on the Rideau, the other being at Newboro, erected for a slightly different reason, to prevent Upper Rideau lake from draining through the cut should the Newboro lock fail.
As for poor Daniel and his dam, it is unknown if it was reconstructed. A few years later, in about 1840, Henry Van Luven registered a deed on the land occupied by Ansley’s mill. By about 1848 he had laid out lots as a the foundation for a town which he planned to call Rockville. When crown mill sites became available for purchase in 1857, Van Luven bought the rights. The name Rockville had been turned down by the postal inspector and a new name, Battersea, was chosen for the community. Van Luven erected a new mill on the site at that time. The Rideau Canal works were never flooded again, although battles between the Rideau Canal and millers continued for decades, mostly on topics such as availability of water for milling (often in competition for water needed for navigation) and the discharge of debris, notably sawdust, by the mills, into the Rideau Canal. The safety gate at Upper Brewers never saw use and it was removed in late 1847 with the supporting piers removed the following year. Behind the story This story is based mostly on the facts stated in Colonel By’s letter of May 30, 1832. The use of flash boards on the dam is an assumption based on By’s statement that the temporary dam was built of “rough boards and Slabs” intended to keep the water about 2 feet higher than the original mill dam. The most common mill dam of the period was the simple log dam, built by putting long logs at an angle into the upstream flow (see diagrams below). The force of water against the angled front actually helps to lock in the dam. A problem with this type of dam is that, to be structurally strong, the angle has to be kept low and therefore the maximum height of the dam is determined by this angle and the length of the logs available for use.
Flash boards, still in use today, are used as a simple measure to impound a bit of extra water. They are erected on top of the dam. Since they are at the top, they aren’t subject to the same amount of hydraulic pressure as the lower parts of the dam. But the weight of water is no trivial matter, and to be successful, proper bracing and strong material must be used. Colonel By’s comments about rough boards and slabs indicates that Ansley was using sawmill scraps and clearly, however he constructed a temporary dam to hold back extra water, it wasn’t of sufficient strength and it broke under the weight of water. A fear of any canal builder is that a lock will get overflowed. On the Rideau it wasn’t so much the possibility of dam failure as it was spring flooding that was the main excess water worry. The problem with flooding is that a lock is in essence a dam. In a Rideau lock, a layer of clay behind the stonework (in some cases today replaced by cement) forms the impermeable barrier. If a lock gets overflowed, the turbulence of the water can start to quickly erode this impermeable material behind the stonework and eventually wash away the entire lock. There are several design features used in the building of the Rideau Canal to prevent this from ever happening. One is the flood guard, which is the height of the stonework above the normal water level. Go out to any Rideau lock today and you can see this for yourself, the “head lock” (upstream lock) at most lockstations (all stations that are in an uncontrolled environment such as a river or lake) will have the stonework a few feet above the normal water level. With other locks, such as internal locks in flight lock, the stonework is just a few inches above the normal water level since the water level can be well controlled. The extra elevation of the stonework on the head lock is designed to accommodate the rise of water during normal spring flood. The second feature is the design of the lock gate. If you look at a Rideau lock gate, you’ll notice that the top rail of the solid section of the gate, is actually about a foot or so below the height of the stonework. This means that as water rises against the lock, the first thing that will happen is that it will flow into (rather than over) the lock and out the other end. The lock will start acting as a weir and in cases of minor flooding, this will allow the lock to pass sufficient water to prevent overflowing, without doing any damage to the lock. A third feature is that in some locations such as Upper Brewers, the man-made berm (embankment) that helps to impound water ahead of the lock, is slightly lower than the stonework. So, like the gate, water will start to flow over the berm , rather than over the lock. You might lose that section of the canal, but it is much easier to reconstruct a berm than it is a lock. Of course the main flood control feature is the weir. Originally all of the dams on the Rideau were going to be overflow dams, but once Colonel By saw the Rideau and Cataraqui rivers in full spring flood, he quickly re-evaluated his plans and added a weir at each lockstation. The height of most of the dams (with a few exceptions such as Clowes, Nicholsons and Black Rapids) was raised to turn them into non-overflow dams. The weir serves as a water level manager, stop logs are either added or removed from the weir to increase or decrease flow. The main flood prevention is to use the weir in late winter to draw down the bodies of water ahead of the locks. This provides reservoir capacity for the spring melt, meaning that all that excess water doesn’t have to be passed through the system at once (which would cause a flood and potentially overflow a lock). In terms of the title of this story, could there really have been a “wall of water.” Possibly, depending on how fast the water rushed out of Loughborough lake. As Cranberry Lake started to fill up with this overflow, the constriction at today’s Round Tail, the narrow entrance to the Cataraqui River above Upper Brewers, would have forced the flood water higher and faster, similar to a tidal bore. We know that the flood washed away a coffer dam. This would have required a lot of force. This is one of the few places on the Rideau where such an event could have happened. Once the canal was built, millers on the Rideau Canal itself used water that was controlled by canal staff. For instance, at Merrickville, the canal weir was upstream of Merrick’s mill dam, so even if his mill dam broke, the canal weir would prevent any flooding. Of course if the canal weir broke (which some did) then flooding could happen, but those are other stories. There were only a few other dams placed in the upstream reaches of the Rideau. For instance, there was Drummond’s dam at the outlet of Hart Lake, Stoddard and Manhard’s dam at the outlet of Westport Sand Lake, Clothier’s dam on Kemptville Creek, and in the mid-1800s, Tett’s and Chaffey’s dam at the outlet of Devil Lake. But none of these impounded the amount of water that Ansley’s dam at the southeast outlet of Loughborough Lake did and thus never posed the same level of risk. 
Sources: Leffel, James & Co., "The Construction of Mill Dams," James Leffel & Co, Springfield, Ohio, 1874. Moore, Jonathan, "Rideau Canal National Historic Site of Canada: Submerged Cultural Resource Inventory," Underwater Archaeological Services, Parks Canada, Ottawa, April 2005. 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
canal dam (which exists today at Davis Lock), shown on the right. The flat top on the log dam was a temporary bridge of planks added by the contractor, Robert Drummond. 
