Complex sentence: The ponds were fed from the river above a weir (now removed) on the upstream side of the viaduct, and provided both power and processing water to Reddish Vale Print Works, a calico printing works dating from before 1800.
Split into simpler sentences: The ponds were fed from the river above a weir (now removed) on the upstream side of the viaduct. The mill ponds served Reddish Vale Print Works, a calico printing works dating from before 1800.