For the past three years, municipal police from Dharan Sub-Metropolitan City have been maintaining continuous surveillance to protect the catchment area along the Bhedetar–Dharan section of the Koshi Highway.

The deployment began in 2022 following a rise in cases of passengers and drivers urinating and defecating along the roadside, which led to the pollution of local water sources.

Authorities have placed particular emphasis on the Nishane Khola and Sardu catchment areas in Dharan-4. These watersheds, originating from the Bhedetar hills in Dhankuta, serve as the primary sources of drinking water for Dharan.

The system also includes water flowing from the Chiuribas, Suryodaya Buddha Bihar and Sanguri Bhanjyang areas.

City police are stationed in the Anpgachhi area for 12 hours each day. They strictly prohibit open defecation and urination within forest boundaries, as well as the felling of trees and clearing of vegetation. Monitoring also restricts unauthorised digging, ploughing or excavation of land, the construction of houses, and the transport of forest products.

The Nishan Saranga Community Forest Users Group has been actively supporting the conservation campaign. The initiative was launched by Harka Sampang, the then mayor of Dharan Sub-Metropolitan City, who prioritised the cleanliness and protection of watersheds following the 2022 local elections.

The deployment has led to a noticeable improvement in the environmental condition of the area. Previously, open defecation along roadsides and within forests caused foul odours and the accumulation of waste near water sources, which would be washed into the drinking supply during the monsoon.

According to local residents, the strict monitoring has also helped raise public awareness.

Gyan Bahadur Katuwal, a driver from Dhankuta, said vehicles are no longer allowed to stop for passengers to relieve themselves in the protected zone, resulting in a significant decline in littering and pollution.