PowerStream is the second largest municipally-owned electricity distribution company in Ontario delivering power to more than 325 000 residential and business customers in the communities of Aurora Alliston Barrie Beeton Bradford West Gwillimbury Penetanguishene Markham Richmond Hill Thornton Tottenham and Vaughan where the corporate headquarters are located. It was formed as a result of the merger of Markham Hydro Hydro Vaughan and Richmond Hill Hydro that took place in 2004.