The steam-powered No. 3 Mill was built in 1871 along the southern shore of the Ottawa river, east of the Madawaska. It burnt in 1875 and a new mill was built on the same site, opening for production in 1882. It was equipped with the newest machinery of the day, including a 190 foot "Iron Bullet Waste Burner." With the construction of Mills 3 and 4, output grew immensely and the McLachlin Bros. were producing 60,000,000 feet of lumber in a good year. A newspaper article from 1923 stated that there was a downturn in business and that only Mill 3 and 4 were in use for a few months per year. The mills ceased operation in 1929. It was demolished in 1937.