Do you know that the city of Toronto literally stands on long-lost and well-forgotten ancient rivers, hidden deep underground? These hidden rivers remind of themselves by twisting the city roads, wetting basements, or otherwise distorting our urban infrastructure, housing, and other constructions. Helen Mills, a former student of philosophy and physical geography at the University of Toronto, and now owning an organic gardening service and a courier company, has been the first to rediscover and map some of our forgotten creeks and rivers. 

When driving around the city, Helen Mills became curious about some strange traits of natural geography of Toronto - curved street layouts, dead ends of roads, sudden turns, twists, rises and dips of the landscape, and other oddities. These "exploration trips" eventually made her an expert on Toronto's urban landscape.

The channels of Toronto ancient springs, known now as Walmsley Brook, Taddle Creek, Mud Creek, or Cudmore Creek, were once carved by melting masses of ice after the last glaciation period.  For thousands of years, they were freely running across wild lawns and valleys of the future city of Toronto. As time passed by, these small rivers slowly disappeared underground, destructed by the city development and sometimes turned into sewer courses, but they are still alive and continue their lazy flow underneath our houses and highways. 

In the 1830s, when Toronto was just a small town of about 10,000 people and was known as "Muddy York" due to poor city sanitation, it was a filthy and smelly place with rivers and streams serving as garbage repositories, full with sewage, manure, and dead animals. Contaminated waters and filth led to the spread of infectious diseases among city dwellers, such as several outbreaks of deadly cholera. Later, in the second half of the 19th century, the city officials agreed that clean drinking water, proper disposal of sewage, and improved sanitation were crucial to the well-being of the Torontonians. The city started constructing a sewer system and water-filtrating plants. Hidden rivers, creeks and steams of Toronto, following the natural topography of the city, became incorporated into this newly-developed sewer system.

If you happen to lift a sewer grate located at the Philosopher's Walk of the University of Toronto,  just at the crossroad of Hoskin Ave. and Bloor St., you will hear a clear roaring sound of once full Taddle Creek that flows southeast from are University area. Although by now this creek has mostly run off, it still carries some water to the Don River.

Mud Creek, sometimes called Mount Pleasant Brook, also flows southeast to the Don River, but starts its course near Downsview Airport of Toronto.

The riverbank of a Taddle Creek is located just under a downtown gas station at the intersection of Sherbourne and Richmond. Its ancient bed is reflected in the curved alleyway and a steep incline of the area's geography. Parts of the Taddle Creek went underground at different historic periods, but this downtown portion became hidden one of the first.

The natural heritage of our city, which also includes our underground rivers, is protected by two well-established groups of community naturalists and environmentalists, known as the Toronto Green Committee and the Toronto Field Naturalists. Together with activists of these green organizations, Helen Mills started a work to rediscover, map, and explore the history of forgotten creeks of Toronto. The work turned into an ongoing field exploration involving regular walking trips with up to 60 people looking for and mapping the hidden river beds. The walking tours are free of charge and everybody interested in the green movement and dedicated to preserving the natural heritage of Toronto can join them. Exploration tours usually last about two hours and are taken place in good weather on weekends. Mill says that these walks educate people and help them see the connection between things hidden underground and manifested on the surface.