Which department is responsible for repairing ditches and dams?

Village committees and water conservancy departments are responsible.

Take the countryside as an example. After the autumn harvest every year, the village will repair the canals for agricultural irrigation next year. At this time, the village Committee will convene a villagers' congress for approval. And submit an application report to the township and sub-district office water conservancy station (water conservancy engineering company). The staff of the water conservancy station went to the village for inspection and guidance at the first time, and the policy strongly supported it!