What’s it worth? Tiverton paying to have power plant appraised Marcia Pobzeznik TIVERTON — Tiverton and Rumford, Maine, a small town of 5,800 residents in the foothills of the western part of the Pine Tree state, are going through the same process right now: figuring out how to tax one of their biggest taxpayers going forward. The two towns are home to Tiverton Power and Rumford Power, natural gas-fired electric generating plants that were built about the same time by the same company some two decades ago. Both towns entered into 20-year agreements with the original owners, in lieu of taxes. Tiverton’s tax treaty expired at the end of 2020; Rumford’s tax increment financing agreement is due to expire this March, but a new one has been negotiated and will be put to Rumford voters on Feb. 24, said Rumford Town Manager Stacy Carter.