Waru-Waru Weir is one of the weirs in Bone Regency which was established in 2014, located in Batu Gading Village, Mare District, which serves 1000 Ha of agricultural land in Mare District, where the majority of the population work as rice farmers, and depend on the results of the rice fields for their living.  In 2017 there was a flood which caused the upstream right retaining wall to collapse due to overtopping of the flow passing through the weir. This is because the capacity of the spillway is unable to pass the flood discharge estimated at Q100, so it is highly hoped that the function of the weir building will be optimized, so that it can support and maximize agricultural yields. The Waru-Waru Weir should be able to pass a discharge of Q100, but changes in land use upstream have caused a change in the value of Q100, so it is necessary to re-plan the spillway capacity of the Waru-Waru Weir. Based on the results of the hydrological analysis, it was found that Q100 was 778.18 m3/sec, so it was necessary to increase the width of the overflow weir by 20 m towards the right in height. The elevation of the additional overflow weir is readjusted to the highest rice field elevation and the width threshold at the intake gate so that +43.63 is obtained. Flood water level above the overflow weir at flood discharge Q100 = +46.88 so that there is still a 1.00 m guard height against the top elevation of the weir +47.88.