TORONTO — Drivers abandoned cars in knee-deep water in a downtown underpass Wednesday after thunderstorms flooded roads, cut power to about 65,000 Toronto Hydro customers and tested a basement-flooding program that has already spent $1.3 billion.Vehicles stalled in the Lower Simcoe St. underpass near Bay St. Passengers waded out as water filled the corridor. In North York, streets around Lawrence Ave. and Dufferin St. were underwater. OPP closed the Hwy. 404 southbound on-ramp at Steeles Ave. in Markham after a vehicle became stuck.The Lower Simcoe underpass has flooded repeatedly since it opened in 2009. A city study found combined-sewer overflow and an undersized storm pipe dump water into the low point. Temporary work was done years ago. That project has not stopped the underpass from filling again.Environment Canada’s station at Pearson International Airport recorded a thunderstorm with heavy rain at 5 p.m., with north winds of 44 km/h gusting to 84 km/h and visibility down to five kilometres. The weather office had warned of hail up to ping-pong-ball size, as much as 50 millimetres of rain in a short burst and a tornado risk in parts of southern Ontario. Emergency alerts went to phones as downtown skies went dark.The downpour hit ground already wet from earlier storms. The Toronto and Region Conservation Authority said some watersheds had recorded 59 millimetres, after 55 millimetres fell in parts of the region Tuesday. Rivers in the Carruthers and Duffins watersheds were expected to rise well above normal..Pearson warned of delays. Air Canada said flights at Pearson and Billy Bishop Airport could be affected. GO Transit closed the east tunnel at Pickering GO because of flooding. CP24 reported no service on TTC Line 6. OPP told motorists to avoid unnecessary travel.Before the worst cells arrived, Mayor Olivia Chow said the city was “prepared,” drain basins were being cleared and “all the divisions … are all set.” She activated the emergency operations centre and told residents in immediate danger to call 911.Toronto Hydro said about 65,000 customers were without power and that more storms could slow restoration. One outage from Bloor St. West to St. Clair Ave. and Spadina Rd. hit about 6,800 customers. Hydro One was reporting about 51,000 outages across Ontario at the same time, including more than 11,000 in Hamilton.Toronto Water projects that about $1.3 billion had been spent by the end of 2025 on Basement Flooding Protection Program construction, design and studies. Staff now put the full price of the work at $22 billion, up from an earlier $18-billion estimate. The 10-year capital plan sets aside about $2.2 billion for the program. City documents say construction from 2019 through 2025 reduced risk for more than 15,800 properties.The private-side subsidy program has issued about $86 million on roughly 59,000 applications, about 14 per cent of eligible owners. After 2024 storms flooded more than 1,000 homes, council raised the maximum subsidy to $6,650 per property as of May 1. All 67 environmental assessments are finished. A prioritization study to decide what actually gets built is only starting in 2026.Hydro One has already told customers to prepare for outages. At the time this article was published, police reported no major highway collisions tied to the storm. Crews were still counting downed trees and flooded roads.
