Subangdaku, the province's largest river, created an issue over the area. It can be considered a braided river composed of several channels from near areas that divide and reunite forming an alluvial fan with a very wide floodplain. As such, the river usually became hazardous during typhoons after heavy rains. The river has overflowed, spilling its waters on the low-lying towns of Liloan and San Vicente and destroyed an ongoing flood control project worth millions of pesos. The river meanders along its course, ever changing its way over time. During the time it floods, it destroys every side of its course. In 2001, portions of the road and banks in Barangay San Miguel along the river were destroyed, including part of the Philippine National Road. Local officials blamed the rechannelization and uncontrolled quarrying of gravel and sand at the side of river as the cause of the flood. At a meeting on March 18, 2002, one of the representatives of a government agency alleged that the reason of the incidents of flood and other environmental problems in the river was due to the "Philippine Fault" which caused rocks to rumble down. However, the reason was contended because the fault is a geological feature and environmental problems in the province just occurred that time.