Seeking feedback on…

Seeking feedback on municipal sewer-use bylaws:

The City of Mississauga (“City”) is currently a lower tier municipality and therefore owns and operates the storm sewer system within the city, which includes more than 1,100 outfalls that discharge directly to the natural environment. Included in the receiving watercourses and bodies are fish protection zones and migration routes, areas used recreationally by the public including for sport fishing and the source of our drinking water, Lake Ontario.

As is stated in the Ministry of the Environment, Conservation and Park’s (MECP’s) Provincial Water Quality Objectives (PWQOs), there are many listed contaminants that pose significant environmental concern that may impair water quality. Many of these contaminants are toxic to aquatic life such as fish and aquatic invertebrates, in both the water column and sediment. Others are persistent and/or bio-accumulative and can cause food-web effects when fish, wildlife, birds, and people consume contaminated organisms. Still other contaminants may impair the human use of the water or upset the natural balance of the aquatic ecosystem.

To promote the development of sewer use by-laws, the then named Ontario Ministry of Environment (now MECP) published a template model by-law in 1988. This model by-law has been adopted by many municipalities, including Mississauga, for the development of their storm sewer use by-law. Many of the quantitative water quality values used in the model by-law were derived from the PWQOs and included a dilution factor of 1.5 to 5 times, which assumed some dilution in the sewer pipe and receiving water body. The limits and prohibitions were intended to apply to two cases: for runoff from an industrial process area, and where material had been purposely discharged to the storm sewer as a method of disposal.

It is the understanding of City staff, based on the provisions made under the Environmental Protection Act, R.S.O. 1990, that what is discharged from the municipal storm sewers to the natural environment is the responsibility of the municipality until such time that the source of an impacted discharge is properly identified. MECP Environmental Officers from the applicable District Offices have indicated this to municipal staff during spill events involving the municipal storm sewers. If discharges that exceed criteria in sewer use by-laws are approved by the province and instruments are issued without municipal involvement, it has the potential to complicate enforcement of pollutant discharges at the outfall to the natural environment.

Since the passing of Mississauga’s first storm sewer use by-law in 2005, staff have updated and renewed the By-law on two occasions to account for changing conditions in the City and increased knowledge within the industry. Mississauga is well positioned to continue to manage discharges from permanent foundation drainage without further provincial involvement.