The tiny Forest City dam on the border between Maine and New Brunswick doesn't look like much more than a pile of rusting iron and aged lumber. Plants and weeds grow throughout the rock-and-crib-style dam, which is home to a family of weasels, a rudimentary passage for fish and is used in summer by local kids to float inner tubes through its gates. The dam itself doesn't generate electricity. It was built to help loggers float their timber to local mills. But its three gates have maintained the waters of East Grand Lake on New Brunswick's western border at consistent levels for almost 180 years.