The Little Monocacy River is a 10.1 miles (16.3 km) tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 stream

Stream

A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

 of the Potomac River

Potomac River

The Potomac River flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States. The river is approximately long, with a drainage area of about 14,700 square miles...

. Despite its name, the stream does not feed into the Monocacy River

Monocacy River

The Monocacy River is a free-flowing tributary of the Potomac River, which empties into the Atlantic Ocean via the Chesapeake Bay. The river is long, with a drainage area of about...

. The Little Monocacy is located almost entirely in Montgomery County

Montgomery County, Maryland

Montgomery County is a county in the U.S. state of Maryland, situated just to the north of Washington, D.C., and southwest of the city of Baltimore. It is one of the most affluent counties in the United States, and has the highest percentage of residents over 25 years of age who hold post-graduate...

, Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

, and enters the Potomac just downstream from where the Monocacy enters the Potomac. Its headwaters rise southwest of Comus

Comus, Maryland

Comus is an unincorporated community in Montgomery County, Maryland, United States. Its elevation is . The mostly rural community is located about by car from Washington D.C.-References:...

, and most of its approximately 17 square miles (44 km²) watershed is farmland and pasture (60.56%) or forested land (36.03%).