Maximum discharge along the river is currently at the reporting a streamflow rate of cfs. This is also the highest stage along the Castor River, with a gauge stage of ft at this location. This river is monitored from 1 different streamgauging stations along the Castor River, the highest being situated at an altitude of ft, the .

The Castor River is a 51-mile-long river located in southeastern Missouri. It flows through rural farmland and wooded areas before emptying into the St. Francis River. Historically, the river was used for transportation and as a source of power for mills. The river's hydrology is heavily influenced by precipitation, with high water levels occurring in the spring and low levels in the summer. The river is home to a few small reservoirs and dams, including the Sam A. Baker Dam and the Mudlick Hollow Dam. These dams are used for flood control and recreation purposes, including fishing and boating. The river is also used for agricultural purposes, with fields and pastures located along its banks. The Castor River is a popular destination for outdoor enthusiasts looking to enjoy the river's natural beauty and recreational opportunities.