The remains of the earlier dam can be seen downstream from the Folsom Lake Crossing.
The problem was that the island had been submerged, by and large safely, by an earlier dam.
This early dam, located just downriver of the present Boysen Dam, silted up by 1925 and was removed in 1948.
An early dam, built by the Sassanids to divert water for the town and its extensive irrigable hinterland, did not work properly.
The structure dates to 1835 at the location of an earlier dam designed to catch fish between slats.
The country's earliest major dam is on the Ngum river near Vientiane, providing 150MW mainly for domestic consumption.
It is also recognized as one of the earliest dams constructed of reinforced concrete.
They all were difficult to maneuver through the early dam's locks and by that time, steamboats' barges had replaced them.
The earliest dams were constructed to support ferry operations in low water.
An earlier dam showed the extent of the original mill pool, which was enlarged in 1767.