It flows from Crooked Lake in Noble County to the Wabash River near what is now Battle Ground, about 12 miles (19 km) northeast of Lafayette.

[4] The Nature Conservancy has identified it as one of the top ten rivers in the United States to preserve due to its ecological diversity and the high proportion of endangered species found in it.

Modern changes in the surrounding land use and dredging the river channel affect the silt levels and stream flow, which threaten the mussel populations.

Of the existing species, several are state listed as endangered, including the northern riffleshell (Epioblasma Torulosa rangiana), the wavyrayed lampmussel (Lampsilis fasciola), the kidneyshell (Ptychobranchus fasciolaris), and the purple lilliput (Toxolasma lividus).

Nearly 80% of collected fish are game fish species, including: Largemouth bass (Micropterus salmoides), Yellow perch (Perca flavescens), Walleye (Stizostedion vitreum), Muskellunge (Esox masquinongy), Bluegill (Lepomis macrochirus), Channel catfish (Ictalurus punctatus), Rainbow trout (Oncorhynchus mykiss), White and Black crappie (Pomoxis annularis and P. nigromaculatus), Longear sunfish (Lepomis megalotis), Northern pike (Esox lucius), Rock bass (Ambloplites rupestris), White bass (Morone chrysops) and Warmouth (Lepomis gulosus).