Waterways have historically defined the geography of the Delhi region, though urbanization has altered their flow and health.
* **The Yamuna River:** The principal river flowing through the broader Delhi region. Though spiritually and historically significant, it faces severe ecological and pollution challenges, prompting ongoing riverfront development and cleanup efforts. * **Lakes & Reservoirs:** Historic and engineered water bodies include Hauz Khas Lake (surrounded by medieval ruins and a deer park), Sanjay Lake, and the Bhalswa Horseshoe Lake.