Uncompetitive Intertie Zones

Market Power Mitigation

The IESO is responsible for overseeing and administering Ontario’s wholesale electricity market. Efficient and competitive market — both in its design and in market participant behaviour — helps ensure the reliable availability and competitive pricing of wholesale electricity.

In situations where competition is restricted and one or more market participants hold market power and could exercise it to materially impact prices, the IESO has rules and processes designed to address such situations.

Uncompetitive Intertie Zones

Under the Market Rules (Chapter 7, Section 22.12), the IESO is obligated to designate one or more intertie zones as uncompetitive intertie zones (UIZ). Market Manual 14.1, Section 3 further specifies the process under which the IESO may designate the UIZ.

The UIZ designations are as follows:

Uncompetitive Intertie Zone	Publication date	Designation effective on trading day	Designation ending on trading day	Grounds for decisions
Quebec D5A (PQDA)	Oct 9, 2025	Oct 14, 2025	N/A	New UIZ designation as per s.22.12.1.1 of Ch.7
Quebec B5D/B31L35 (PQBE)	Oct 9, 2025	Oct 14, 2025	N/A	New UIZ designation as per s.22.12.1.1 of Ch.7
Quebec H4Z (PQHZ)	Oct 9, 2025	Oct 14, 2025	N/A	New UIZ designation as per s.22.12.1.1 of Ch.7
Quebec A41T/A42T (PQAT)	Oct 9, 2025	Oct 14, 2025	N/A	New UIZ designation as per s.22.12.1.1 of Ch.7