The City of San Antonio immediately installed stop logs upstream of the gate to block the flow and prevent the water level in the River Walk from dropping. With these gates keeping the water up at a constant level, the River Walk works kind of like a bathtub; it takes a big volume of water to fill up the channel that snakes around downtown. From here, operators can control all the city’s flood infrastructure, including the dams and gates on the river and the flood bypass tunnels that run below ground.