The South River was the key source of power during the heyday of manufacturing in Conway. This dam was constructed during the second half of the 19th century to form a reservoir. It was the biggest masonry structure in Franklin County at the time and was designed to supply the major mills with water especially during the dry months.
View from the cache.
In 1869, during an extreme weather event, the reservoir dam did breach, destroying 14 river bridges and damaging all of the mills along the river, and also pig pens, small buildings, houses, and factories. The reservoir breached for a second time on December 10, 1878.
Communal fears regarding the potential breach of this large reservoir prior to 1869 led to public backing of the "4-40 campaign" where the river channel was straightened and widened to a width of 40 feet for a distance of 4 miles from the reservoir to a point downstream of the village. Straightening of rivers was a common practice in New England during this period. However, this proved disastrous during extreme river flows. Without natural bends, river obstructions, flood plains, vegetation, etc. to slow the flow, river banks were eroded and the river changed course through the village. Recently, the effects were revealed again during Tropic Storm Irene.