But, like the river, the fate of the boathouse ebbed and flowed. The building was in constant battle with the river’s freeze-thaw cycles, and concerns about water pollution began as early as the 1930s. The nail in the coffin came in March 1973, when the seasonal ice breakup took out the swimming raft, and much of the formal swimming there, seemingly for good.

Until 2019. To preserve the boathouse’s historic value — it was recognized as a federal heritage building in 2010 — the National Capital Commission undertook a $20-million revitalization project that included shoring up its deteriorating structure, winterizing, adding a café, event space and offices for the Ottawa Riverkeeper organization and carving out a place for the building’s originators, now called the Ottawa New Edinburgh Club. Outside, the site saw extensive landscaping and restoration, while new public docks were installed to enclose a formal swimming area with two 25-metre lanes, which took careful consideration.

“After doing water testing and current assessments, we realized that it’s a phenomenal place to swim,” she says. “We have some of the best water in the National Capital Region at that location.… Part of that is just the river conditions in that area: it’s a big open channel, has a nice stable, gradual current; it’s got a good flush rate; it’s not near any major stormwater outlets, and it’s deep water.”

Since the newly named River House opened to the public in 2023, regulars like Alan McCullough, a member of the Ottawa New Edinburgh Club and an unofficial historian, have noticed new life breathed into the site.

“It seems to have been a great success,” says McCullough. “On a good day in the summer in the first years, there were people lined up to get in [to swim].”

For years, Dow’s Lake “wasn’t thought to be viable for swimming,” says Halsall. “But when you take a closer look, you have pristine water, these thriving ecosystems with trophy fish in abundance, plenty of species at-risk, protected turtles and birds that are living quite happily and quite successfully there.”

Looking across the water from the new dock near Queen Elizabeth Driveway and Lakeside Avenue, the white pines at the Dominion Arboretum whisper the history of the waterway. What used to be a pine-dotted cedar swamp was razed and flooded during the construction of the Rideau Canal. Over its almost 200-year history as part of the canal system, Dow’s Lake has been put to work. At Commissioner’s Park, where thousands of tulips now bloom each May, was a lumber yard a century ago, with a cannery nearby. When water levels dip in the spring and fall, the shallow parts of the lake sometimes reveal sections of an old causeway that used to bisect the waterway from 1904 to 1928.

Because of that history, and the city’s sewage overflow issues, many thought the water quality in Dow’s Lake was unsuitable for swimming, says Halsall. However, testing for the bacteria E. coli, a standard marker for water quality, throughout 2023, 2024 and 2025 indicated safe levels. The National Capital Commission also assessed human health risks, searching for other water contaminants from the lake’s industrial past, such as lead and cadmium. When those turned up clean, “that really greenlit the site,” says Halsall.