[8] The river originates in Todd County in south central South Dakota, at the confluence of Antelope Creek and Rock Creek near the town of Hidden Timber.

[1] It ends at its confluence with the Niobrara River about 7 miles (11 km) west of Butte, Nebraska.

[13] At a gaging station south of Naper in Boyd County, the river's mean discharge was 138.6 cubic feet per second (3.92 m3/s).

The maximum mean annual discharge was 389.4 cubic feet per second (11.03 m3/s), recorded in 1962; the minimum mean annual discharge was 44.5 cubic feet per second (1.26 m3/s), recorded in 1976.

[14] The peak flow recorded at that point was 9,280 cubic feet per second (263 m3/s), registered on July 1, 1962.