The Ottawa Valley's lumber industry was, at its peak, one of the largest in the world. From the early nineteenth century through to the early twentieth, the valley's forests produced white and red pine that was shipped to markets across the British Empire. The scale of the operations was enormous, and the infrastructure they required, particularly the mills that processed the raw logs into finished timber, was built on a correspondingly grand scale.
When the old-growth timber was exhausted and the industry contracted, the mills closed. Most of the wooden structures were dismantled or burned. But the stone and concrete foundations, the dam structures, and the channels that directed water to the mills have proven far more durable. Today, these ruins are among the most impressive abandoned structures in the province.
The Scale of the Operations
It is difficult for modern visitors to appreciate how large these mill operations were. The J.R. Booth operation in Ottawa, which included mills, lumber yards, and shipping facilities, covered a vast area of what is now downtown Ottawa. The McLachlin Brothers mill at Arnprior stretched for hundreds of metres along the Madawaska River. The Gillies Brothers mill at Braeside was another massive operation.
These were not quaint watermills grinding grain. They were industrial operations employing hundreds of workers, operating multiple saw lines, and processing millions of board feet of lumber per season. Their foundations reflect this scale: massive walls of cut stone or poured concrete, often several metres thick, built to withstand the vibration of heavy machinery and the force of the spring floods.
The stone foundations of the valley's lumber mills were built on an industrial scale and have survived for well over a century.
River Infrastructure
The mills depended on the rivers both for power and for transportation. Logs were driven down the Ottawa and its tributaries every spring, guided by rivermen who controlled the flow using a network of dams, slides, and boom structures. Much of this river infrastructure survives in some form.
Timber slides, channels built around waterfalls and rapids to allow logs to pass safely, were once common on every major river in the valley. Their remains, cut stone channels running alongside natural falls, are among the most atmospheric ruins in the region. The most famous timber slides were at Chaudiere Falls in Ottawa, but similar structures existed at falls throughout the valley.
Boom structures, used to corral floating logs and direct them to the mills, have largely disappeared. But the anchor points, iron rings set into bedrock or massive stone piers built in the river, can still be found. Dam structures, both the massive dams at mill sites and the smaller "splash dams" used to raise water levels for the spring drive, are also common. Some remain intact. Others have partially collapsed, creating unusual water features.
Finding Mill Ruins
Mill ruins are found along every major river in the Ottawa Valley, but the highest concentration is along the Madawaska River between Arnprior and Barry's Bay, the Bonnechere River between Renfrew and Algonquin Park, and the Ottawa River itself between Pembroke and Arnprior.
The easiest mill ruins to find are those in or near towns. At Arnprior, the McLachlin Brothers mill foundation is visible from the town's riverside park. At Burnstown, a picturesque mill ruin stands beside a waterfall in the village. At Renfrew, mill foundations line the Bonnechere River through town.
More remote mill ruins require some effort to reach. The tributaries of the Petawawa and Madawaska rivers, accessible from the back roads south of the Petawawa area, have mill ruins that see few visitors. These sites are often more intact than the urban ones, having been spared the development pressure that affects ruins in populated areas.
Historical maps are essential for finding mill sites. The 1879 and 1881 county atlases show mill locations with remarkable precision, and comparing these with modern maps will reveal dozens of sites. The forgotten places of the Ottawa Valley guide provides additional context for exploring these sites.