No matter where you are, you are in a watershed.

A watershed is an area where the water above-ground and below-ground drains to the same stream, river, lake, bay or ocean.

Watersheds can be very small, such as the watershed for the stream that may flow through your local park. These small streams join together to form larger and larger waterways with larger and larger drainage areas like the Chesapeake Bay and Mississippi River watersheds. 

Image of water moving through a watershed.

The graphic above shows the process of water entering the watershed. When it rains, all of the water drains to one body of water. It falls on land and travels to a stream and eventually a river that empties into a lake or ocean. Water also soaks into the ground to add to groundwater and underground rivers. 
Watershed map .gif repurposed from the Rockingham County, NC

Image of Montgomery County topography
This topographic map shows the changes in elevation throughout the County.
Our County's watersheds are determined by the geography, topography and waterflow.
Montgomery County is in the larger Chesapeake Bay watershed. This means all of the water that comes through, or is from here, goes to the Chesapeake Bay. We also have parts of the Potomac River watershed and the Patuxent River watershed located within our county.

Montgomery County has over 1,500 miles of streams. Pretty impressive! 

There are two major watersheds within the County: the Potomac River watershed, which covers 88% of the County, and the Patuxent River watershed, which covers the other 12%.

How the land and streams are cared for upstream has a significant impact not only to our local environment but to the ecosystem downstream as well.

Find Your Watershed Map

Want to know which watershed you live in and how healthy it is?
Use this Interactive watershed map.
View larger map

County Watersheds

Montgomery County is made up of eight major watersheds and almost 150 smaller watersheds. The map at the top of the page shows streams, tributaries, lakes, and other water features within Montgomery County as well as their health and condition.

All county watersheds are monitored according to a defined schedule at least once every five years. The types and health of fish species and stream bugs (also called benthic macroinvertebrates) provide a snapshot of the health of the watershed.



  • Little Paint Branch
  • Northwest Branch
  • Paint Branch
  • Sligo Creek

Cabin John Creek

Lower Monocacy


  • Bennett Creek
  • Fahrney Branch
  • Little Bennett Creek
  • Furnace Branch

Lower Potomac Direct


  • Little Falls
  • Muddy Branch
  • Rock Run
  • Watts Branch

Patuxent River


  • Hawlings River
  • Lower Patuxent
  • Upper Patuxent

Rock Creek


  • Lower Rock Creek 
  • Upper Rock Creek

Seneca Creek


  • Dry Seneca
  • Great Seneca
  • Little Seneca

Upper Potomac Direct


  • Broad Run and Horsepen Branch 
  • Little Monocacy and Monocacy River

Image of Department of Environmental Protection staff leading a restoration walk at Booze Creek.

DEP staff leading a restoration walk at Booze Creek.
Image of northern red salamanders Northern red salamanders are one of the many animal species that call Montgomery County watersheds home.

How Do Watersheds Affect Us?

Healthy watersheds offer many valuable functions and are essential for appreciating the local natural environment. 

By protecting our watersheds and preventing pollution, we help secure our quality of life and reduce the costs of government cleanup programs. Also, keeping our local waters clean helps protect the water supply and habitat for people and animals that live downstream, allowing them to experience the same benefits.
Image of a beautiful stream.

In a healthy watershed, there are:

  • Recreational opportunities such as fishing, canoeing or boating

  • Habitats for wildlife and fish. Good water quality is important for both fish and their food sources.

  • Lower costs for drinking water. The dirtier the water, the more expensive the treatment before being piped to your home.

  • Aesthetically pleasing surroundings. Clean waterways offer beauty in the landscape.

  • Escape from urban development. Waterfronts are peaceful places that people can enjoy.

  • Homes, businesses, and roads protected from flooding and other natural disasters.

  • Less polluted waters creating better public health and safety. Polluted water can be a human health hazard.

  • Reduced tax burdens to clean up and protect the environment.