| S.No | Sub Basin List | Area | Rivers | District Covered | Reservoirs under WRD Control | No. of Tanks under WRD |
|---|---|---|---|---|---|---|
| Total Chennai basin Area 4959.076 sq.km | ||||||
| 1 | Gummidipoondi | 300.675 sq.km | (Isolated) | Thiruvallur | – | 40 |
| 2 | Araniyar | 846.813 sq.km | Araniyar | Thiruvallur | – | 199 |
| 3 | Nagariyar | 319.833 sq.km | Nagariyar | Thiruvallur | – | 33 |
| 4 | Nandhiyar | 580.606 sq.km | Nandhiyar | Tiruvallur, Vellore | – | 91 |
| 5 | Kosasthalaiyar (Korattalaiyar) | 1948.372 sq.km | Kosasthalaiyar | Thiruvallur, Vellore | Poondi, Cholavaram Redhills, Kannankottai Thervoykandigai | 371 |
| 6 | Cooum | 473.931 sq.km | Cooum | Kancheepuram, Thiruvallur, Chennai | – | 82 |
| 7 | Adyar | 488.846 sq.km | Adayar | Kancheepuram, Chennai | Chembarambakkam | 223 |
| 8 | Kovalam | 300.675 sq.km | (Isolated) | Kancheepuram | – | 78 |
