Ouderkerk. Ouderkerk is a former municipality in the western Netherlands, in the province of South Holland. Since 2015 it has been a part of the municipality of Krimpenerwaard. The former municipality covered an area of 28.57 km 2 of which 1.50 km 2 was water. It was formed on 1 January 1985, after a municipal reorganization. The former municipality of Ouderkerk consisted of the population centres Gouderak, Lageweg, Ouderkerk aan den IJssel, and IJssellaan, all situated along the Hollandse IJssel river.