Vamanapuram River which has a length of 88 kms spreads along the districts Thiruvananthapuram and Kollam. This river originates from Chemunjimotta Hills on the Western Ghats. This river ends up in Anjengo Lake in Varkala. The two main tributaries of this river are Upper Chittar and Manjaprayar rivers. The water from this river is used for supplying drinking water to the Vamanapuram village. The river also turns its flow towards Anchuthengu backwaters through the Attingal. A pilgrim center Koikkal Bhagavathy temple at Attingal is on the Vamanapuram River banks