The river is not navigable along most of its course except the small stretch where it joins the sea. With a watershed of 6,186 km2, the Bharathapuzha basin is the largest among all the river basins in Kerala. A little more than two-thirds of this area (4400 km2) is within Kerala and the remaining area (1786 km2) is in Tamil Nadu. Though Bharathapuzha has a large basin, the water flow is relatively less compared to other long rivers in Kerala because a large portion of the basin is located in the comparatively drier regions (Tamil Nadu and Palakkad Gap). The construction of a number of dams after independence has also reduced the river flow. In fact, in the summer months, there is almost no flow in most parts of the river.