[2][3] A right tributary of the East Rapti River, the Karra originates in the north-eastern Siwalik hills.
It flows through the middle of Hetauda sub-metropolitan city, before draining into East Rapti along with Kukhreni, another (minor) right tributary of East Rapti, in the outskirts of the city, forming a holy Triveni Sangam.
On 24 July 2019, a severe flooding caused by heavy monsoon rains caused the river to gush into human settlement, submerging dozens of houses in Shantinagar and Gardoi localities of Hetauda.
[3] Because it passes right through the city, and Hetauda Industrial district has been built in its banks, it is significantly polluted near the confluence compared to other rivers in the region, although it is as clean as other rivers upstream from the industrial sites in Hetauda.
This is despite a wastewater treatment plant being operated to filter the sewage and waste from the industrial district before it's dumped into the river.