There are at least 18 named lakes and reservoirs in Big Horn County, Montana .
A lake is an area filled with water, localized in a basin, that is surrounded by land, apart from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, and therefore are distinct from lagoons, and are also larger and deeper than ponds, though there are no official or scientific definitions. Lakes can be contrasted with rivers or streams, which are usually flowing. Most lakes are fed and drained by rivers and streams.
A reservoir is, most commonly, an enlarged natural or artificial lake, pond or impoundment created using a dam or lock to store water.
Big Horn County is a county in the U.S. state of Montana. As of the 2010 United States Census, the population was 12,865. The county seat is Hardin. The county, like the river and mountain range, were named for the bighorn sheep in the Rocky Mountains. The county was founded in 1913. It is located on the south line of the state.
The Bighorn River is a tributary of the Yellowstone, approximately 461 miles (742 km) long, in the states of Wyoming and Montana in the western United States. The river was named in 1805 by fur trader François Larocque for the bighorn sheep he saw along its banks as he explored the Yellowstone.
There are 45 streams named Willow Creek in the state of Montana.