Flagstaff Lake was a smaller natural lake when the
Long Falls Dam impounded the Dead River in 1950, enlarging the
lake and turning it into a reservoir used for hydropower electricity production by regulating the flow of the Dead River into the
Kennebec River. At the time, the river drive was still a primary means of delivering timber to the pulp mills downstream. Improved highways and the trucking industry have replaced the river drive. Construction was controversial dating back to 1923, pitting the president of Central Maine Power Company, Walter Wyman, against state legislator and future Maine governor
Percival Proctor Baxter. Flagstaff Lake occupies parts of the abandoned and now submerged townships of
Flagstaff, Bigelow, Dead River and Carrying Place. The dam is high, long at its crest, and consists of a concrete spillway, a long concrete section containing five wide
Tainter gates, a long concrete section containing two Broome gates, and a log sluice, and a long earthen dike. The dam is owned and operated by Brookfield Renewable Energy, but no electricity is generated here. The dam is operated to regulate and augment flows that are used by eight downstream mainstem Kennebec River hydropower projects, and to control flooding. == Climate ==