Lanham is situated within the Anacostia River watershed. The primary waterways moving through the area are small streams and creeks rather than navigable rivers.
* **Folly Branch** and **Beck Branch** are notable local tributaries that weave through the residential neighborhoods and parklands, eventually feeding into the Northeast Branch of the Anacostia River. These wetland corridors play a vital role in local stormwater management and providing natural habitats for native flora and fauna.