July 15, 2011 - will Maine have a new largest dam?

Since 1954, Maine's largest-capacity hydroelectric dam has been the 85 megawatt Harris Dam on the Kennebec River - but it may soon lose its title to another project on the same river.

Water spills over the last falls on the Cathance River in Topsham, Maine. These falls powered a sawmill as early as 1716.

Harris Dam may soon lose its title as Maine's largest dam -- but not because a new dam is being built. Rather, dam owner FPL Energy Maine Hydro LLC -- a subsidiary of NextEra Energy Resources -- has embarked on a program to improve the efficiency of the three turbines at Wyman Dam, the next dam downstream from Harris.

Wyman Dam, currently rated at 83 megawatts capacity, was built in 1930, 24 years before the Harris Dam. Improvements to two of the three Wyman turbine generators have already occurred, and NextEra now proposes to complete the project.

Between the recent efficiency upgrades and a closer look at older improvements, NextEra now thinks the overall licensed project capacity should increase from 83,700 kW to 88,010 kW, an increase of 4,310 kW. NextEra has applied to the Federal Energy Regulatory Commission for a license amendment to reflect these upgrades.

Comments on this proposal are due by August 5, 2011. If approved, Wyman Dam's newly-tallied 88 megawatts of capacity will slip past Harris Dam's 85 MW to become Maine's largest hydroelectric dam.