Thousands of Iranians gathered in a dried up riverbed in the central city of Isfahan to protest mismanagement of water resources, state media reported.

Farmers and their supporters carried signs reading “Where is my Zayandeh River?” as they stood on the cracked ground where the Zayandehrood River once flowed, next to the famous Khaju bridge.

The river, the largest river in Iran’s central plateau, has largely disappeared for the past two decades because of drought and diversion of water to industry and farming upstream.