Get the latest (2023) update of the City’s Wet Weather Flow Master Plan (WWFMP). Attachment and supplementary information included.


Toronto’s Wet Weather Flow Master Plan (WWFMP) is a long-term plan to protect our environment and water quality in the Lake, rivers, streams and other water bodies from the rain and melted snow (stormwater).

Toronto’s urban environment leaves little place for rain and snow to be absorbed. As a result, stormwater makes its way into the nearest creek, river or storm sewer, picking up debris, including what is on our roofs, roads, cars and sidewalks, before discharging into the nearest waterway. This includes grease, bird/animal droppings, pet waste left on sidewalks, garbage, bacteria and other pollutants.

The result can lead to degraded water quality conditions, stream bank erosion, loss of fish habitat and basement flooding.

The plan sets out 13 objectives, under four categories:

Water Quality in Local Waterways

  • Meet guidelines for water and sediment quality.
  • Virtually eliminate toxins through pollution prevention.
  • Improve water quality in rivers and the Lake so that they are healthy for swimming.
  • Improve aesthetics.

Water Quantity

  • Preserve and re-establish a natural hydrologic cycle.
  • Reduce erosion impacts on habitats and property.
  • Eliminate or minimize threats to life and property from flooding.

Natural Areas & Wildlife

  • Protect, enhance and restore natural features (eg., wetlands) and functions.
  • Achieve healthy aquatic communities.
  • Reduce fish contamination.

Sewer System

  • Eliminate combined sewer overflow sanitary sewage.
  • Reduce infiltration and inflow to sanitary sewers.
  • Reduce basement flooding.