Oostendam is a Dutch village. It is located in the municipality of Ridderkerk, within the province of South Holland. In 2004 it had 640 residents. The Dutch word Oostendam translates to Eastern Dam.The village was founded in 1332 when Count William III had dikes built around a side-arm of the river Waal. As it is currently a dead branch of the river, the locals commonly refer to it as Het Waaltje, which means The Little Waal.