January 31, 2020

The City of Toronto (City) and Enwave Energy Corporation (Enwave), as co-proponents, are carrying out an assessment to examine expanding the existing Deep Lake Water Cooling (DLWC) supply. Enwave provides cooling to over 80 buildings in downtown Toronto through its District Energy System.

The City and Enwave operate under an existing Energy Transfer Agreement (ETA) that facilitates the transfer of cooling energy from the City’s drinking water infrastructure into Enwave’s District Energy Supply through heat exchangers.

There is continued growth in demand for cooling Toronto’s downtown core, and Enwave anticipates about 35 percent increase in its customers’ cooling demands in the near future.  There is an opportunity for the City and Enwave to amend the Energy Transfer Agreement and expand the DLWC system to meet the cooling demand in a mutually beneficial way. This assessment will examine the proposed expansion of the DLWC supply.


December 2019 Toronto City Council Direction


More details are available at Enwave’s website

DLWC map, please contact Mae Lee at 416-392-8210 or mae.lee@toronto.ca if you need help reading this
DLWC map

How does the system work?

The City’s Island Water Treatment Plant (Island WTP) draws cold water from three intake pipes that extend deep into Lake Ontario. Before entering the City’s distribution system, the treated water passes through Enwave’s Energy Transfer Station (ETS).  There, heat exchangers transfer thermal energy from the district cooling water loop to the cold drinking water.  The rechilled cooling water is circulated through a closed loop running throughout downtown to provide cooling to buildings, and then Enwave recycles the heat, returning the warm water to the ETS to repeat the process.

Study Process

The assessment is being planned in accordance with the Municipal Class Environmental Assessment (MCEA), Schedule “B” approved planning process under the Environmental Assessment Act. The process provides members of the public and interested stakeholders with opportunities for input at key stages of the assessment. The assessment will define the existing problem and opportunity, review potential impacts, evaluate the alternatives and identify the recommended solution.

Notice of Study Commencement



Personal information received by the City in response to this notice is collected under the authority of Part II.1 of the Environmental Assessment Act and s. 7 and 8 of the City of Toronto Act, 2006 for the purpose of consultation, preparation and submission of a Municipal Class Environmental Assessment (MCEA), the maintenance of an associated project file, (which shall be a record maintained for the purpose of being available to the general public), reporting to City Council as required, submission to the Ministry of the Environment, Conservation and Parks (MECP) as required, and the execution of the Deep Lake Water Cooling (DLWC) Expansion project.

By submitting information in response to this notice, you consent to the disclosure of this information to the City’s co-proponent, Enwave Energy Corporation and its consultants, including but not limited to advisors and to MECP for the purpose of consultation, preparation and submission of a MCEA, the maintenance of an associated project file, submission to MECP as required and the execution of the DLWC Expansion project.

Questions about the collection of personal information may be addressed to the contact person noted in this notice.

What is a Class Environmental Assessment?

Ontario’s Environmental Assessment (EA) program promotes good environmental planning by determining and managing the potential effects of a project prior to implementation.

Environmental Assessments identify and consider the potential impacts a project may have on a natural, social, economic, and technical environments.

If concerns regarding a project cannot be resolved in discussion with the City of Toronto, a person or party may request that the Minister of the Environment, Conservation and Parks (MECP) make an order for the project to comply with Part II of the Environment Assessment Act (referred to as a Part II Order), which addresses individual environmental assessments.

To submit a Part II Order request, refer to the MECP website for instructions.