A dike, a floodway and a town built on the low ground behind them

There is a two-kilometre earth structure running through the middle of this town and most people who live here have walked on it without knowing what it is. The Pretty River Dike was built in the 1970s to keep floodwater out of downtown Collingwood, and it runs from the southwest corner of Peel and Lynden, past the old CN rail bridge that is now the Siding Trail, along Hume Street and the Pretty River Parkway, and out to Oliver Crescent near the shore of Nottawasaga Bay.

It is built to contain the Provincial Regulatory Storm Event — a storm with less than a one per cent chance of occurring in any given year. In 2026 the Nottawasaga Valley Conservation Authority put boreholes through it and installed internal pressure monitoring as part of a safety review of its structural condition. That work is worth knowing about if you own property behind it, and it is a more useful thing to know than anything on a restoration page written for the whole province.

The floodway nobody notices

The other half of the arrangement is Black Ash Creek, which drains roughly 3,000 hectares into Collingwood harbour. Before the 1970s it was three separate streams — the Black Ash, the Taylor and the Underwood — and the latter two were diverted into the first for flood control. The NVCA names Collingwood among the communities in its watershed most susceptible to flooding, and that infrastructure is why the town is not worse.

What this means for a basement on the west side

Flood control structures manage the river. They do not manage the water table, and they do nothing about a storm sewer that surcharges, a sump that stops, or a slab-wall joint on low ground. Those are the three that actually put water into basements in this town, and they are unaffected by how well the dike performs.

Two Collingwoods, two completely different losses

Around six in ten dwellings in the Collingwood area were built before 1990, and roughly one in five before 1960. Between the harbour and Hurontario that shows up as rubble and stone foundations, plaster on lath, cast-iron drains and floor assemblies that were never designed around a laundry on the second storey. On the south and east edges it is fifteen-year-old subdivisions with tight envelopes, finished basements and a sump pump doing real work.

Water damage restoration in a Collingwood heritage house

The asbestos question arrives before the first cut. Ontario Regulation 278/05 requires a report on whether material that may be disturbed is asbestos-containing before an owner arranges demolition, alteration or repair, and vinyl floor tile, tile adhesive, some plasters and older mechanical insulation are all candidates in a building of that vintage. It is a legal step and an emergency does not suspend it. What it means in practice is that a crew arriving at 9pm stabilises and extracts, and the opening up happens once the question is answered.

Emergency water extraction near the harbour

The century stock down here has one further complication: the assemblies are not standard, so the boundary of the wet area is genuinely hard to predict. Water inside a balloon-framed wall runs from the sill plate to wherever the first fire-stop is, which may be the attic. Finding the edge is most of the first visit, and a scope written without doing it is a guess. See what extraction and drying involves and what it costs here.