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

The Thornapple River is a 100-mile-long river located in Michigan, United States. It flows through Kent, Barry, and Ionia counties, and is a tributary of the Grand River. The river was named after the thornapple plant, which is abundant in the area. The Thornapple River watershed covers approximately 700 square miles and is home to several reservoirs and dams, including the Tippy Dam, the largest hydroelectric power producer in the state. The river is used for various recreational activities such as fishing, kayaking, and canoeing, and the surrounding areas are popular for camping and hiking. The river also supports agricultural activities such as farming and cattle grazing. Over the years, the Thornapple River has played a crucial role in the development and growth of the communities it passes through.