| name | image | Average flow (m³/s) | basin (m²) | Height (m) | origin location | mouth location | Length (m) | latitude (°) | longitude (°) | canyon | Map |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Line Creek (Grass River tributary) | 46,101,784 | Grasse River | 44.7152777800 | -75.1525000000 | Map | ||||||
| Little River (Grass River tributary) | 258,480,816 | Grasse River | 44.5786111100 | -75.1633333300 | Map | ||||||
| Middle Branch Grass River | 163,169,248 | Grasse River | 44.3758333300 | -75.0608333300 | Map | ||||||
| Nettle Creek (Grass River tributary) | 42,993,800 | Grasse River | 44.7016666700 | -75.1575000000 | Map | ||||||
| North Branch Grass River | 155,917,280 | Grasse River | 44.4244444400 | -75.1075000000 | Map |