The designation is from just below the Delaware Dam in Delaware downstream to old Wilson Bridge Road in Worthington.

The river is located within the rapidly developing area of northern Columbus and southern Delaware County. While development has been intense, the river has actually seen an increase in water quality and was upgraded to an exceptional warm water habitat by the Ohio Environmental Protection Agency. The river is within a 1/2 hour drive of over 1.5 million people.

The river valley is characterized by gently rolling to relatively flat topography. The steep shale banks flanking the stream enhance the natural quality that signifies this river.

The most spectacular shale banks, rising some 110 feet above the streambed, are found along Highbanks Metropolitan Park.

These banks are often dissected by ravines which cut through and expose the underlying rock strata including the Ohio black shale, noted for its presence of large "ironstone" concretions.

The river's name has an interesting history. Olentangy was a name given to this river in 1833 by a legislative act that was attempting to restore Native American names to certain rivers in the state.

The word Olentangy literally means "River of Red Face Paint." This name actually belonged to Big Darby Creek further to the west, where the Wyandots of the Columbus area got their red face paint.

The Olentangy River should have been named the Whetstone River. The literal translation of the Delaware Indian name for the Olentangy River - "Kiin ansh ikan Siipu nk" is "Sharp/More and More/Tool/River," or more precisely Whetstone.

Both the Native Americans and early settlers used the black Ohio and Olentangy shale found along the river for whetstones to sharpen their tools.

The Olentangy, while continuing to experience development pressure, has retained a forest corridor which has greatly assisted in protecting its 54 species of fish. The relatively high quality of the Olentangy and its wooded banks provides habitat for a variety of breeding birds and other animals.

The predominate species of trees which make up the forested streamsides include willow, red and silver maple, sycamore, oak, basswood, and green ash.