Twin Creek is a western tributary of the Great Miami River. Its watershed encompasses 316 square miles (202,240 acres). Twin Creek's headwaters orgininates from south-central Darke County. The main stem of Twin Creek is 46.2 miles long with 103 miles of tributary streams.
The subwatersheds located within the Twin Creek watershed play an important role to the health of the watershed. There are 15 subwatersheds located within the Twin Creek drainage. They are:
Twin Creek above Miller's Fork
Miller's Fork
Twin Creek below Miller's Fork to above Price Creek
Swamp Creek
Price's Creek
Twin Creek below Price's Creek to above Bantas Fork
Bantas Fork above Goose Creek
Goose Creek
Bantas Fork below Goose Creek
Twin Creek below Bantas Fork above Aukeman Creek
Aukeman Creek
Twin Creek below Auekman Creek above Tom's Run
Tom's Run
Twin Creek below Tom's Run to Greate Miami River
Little Twin Creek
Twin Creek Watershed is located within four counties (Darke, Preble, Montgomery, and Warren), sixteen townships (Butler, Twin, Monroe {Darke}, Jefferson, Monroe {Preble}, Harrison, Washington, Twin, Gasper, Lanier, Gratis, Clay, Perry, Jackson, German, and Franklin) and eleven incorporated communities (Castine, Ithaca, Gordon, Eldorado, West Manchester, Lewisburg, West Alexandria, Gratis, Germantown, Farmersville, and Carlisle). The largest towns in the watershed are Germantown and Carlisle.