Do You know which river was given to us by Sage Agasthya?

I know everyone will answer as River Kaveri...But no....He didn't give us Kaveri directly and I have already told a story on how river Kaveri was formed. Let me come to the answer...It's named as " Kusaithalai ", it's a perennial river which is seen to the west of Tiruthani near Vellore.  

Let me now tell you how this river came into existence. Once upon a time there was a war between Lord Indira and an Asura named Vruthirasura. To escape from Lord Indira, Vruthirasura went inside the ocean to hide himself. Knowing that he is inside the ocean Indira requested sage Agasthya to help him out.
As per Indira's request Sage Agasthya drank all the water of the ocean, and Vruthirasura was finally found and killed.

Now everyone may be wondering about the river! Yes the story is not yet over! After the incident sage Agasthya started getting severe stomach ache. To cure himself, he prayed to Lord Muruga to cure him. But Lord Muruga told him that he was suffering from stomach ache as he had taken in a lot of other organisms from the sea along with the water. As Agasthya had the capacity to digest everything, he had digested a few of them which had cursed him and to relieve himself from the curse he would have to pray to Lord Shiva. So sage Agasthya decided to pray to Lord Shiva to cure himself. He took a small piece of Kusa grass or holy grass and told some mantra and threw it and it went and fell on a hill towards the west direction of Tiruthani. It got  transformed into river called Kusaithalai which means from Kusa...Sage Agasthya built 108 Shiva temples with Shivlingas and prayed to all of them and got relieved from his stomach ache.