The Koshi Barrage, also widely known as Koshi Mahasetu, is one of the largest river barrages in the world. Built across the mighty Koshi River (also spelled Kosi) between 1958 and 1962, this monumental structure stretches 1,150 metres in length and features 56 sluice gates that regulate the flow of water downstream. The barrage stands at the India–Nepal border in Supaul district, Bihar, and was constructed as a joint project following the historic Koshi Agreement signed between India and Nepal in 1954.

The Koshi River has long been called the “Sorrow of Bihar” due to its history of catastrophic floods that have ravaged the plains of northern Bihar for centuries. The river, originating in the Himalayas of Nepal, carries an enormous sediment load that causes its course to shift dramatically over time. The construction of the Koshi Barrage was undertaken primarily to tame these floods, provide irrigation to the surrounding agricultural lands and generate hydroelectric power. The barrage and its associated embankments have played a crucial role in protecting millions of people living in the Koshi floodplain, although the region continues to face challenges during heavy monsoon seasons.

Beyond its engineering significance, the Koshi Barrage area is a place of remarkable natural beauty. The vast expanse of the Koshi River, with its braided channels and sandy islands, creates a stunning landscape that changes with the seasons. The region is home to the endangered Gangetic dolphin, which can sometimes be spotted surfacing in the deeper channels near the barrage. Between August and October, migratory Siberian birds arrive in large numbers, making the area a delightful spot for birdwatching enthusiasts. The Koshi Tappu Wildlife Reserve on the Nepali side of the border further adds to the ecological importance of this region.

Visitors to the Koshi Barrage can walk along sections of the barrage road and enjoy panoramic views of the river stretching towards the Himalayan foothills. The sight of water rushing through the sluice gates during the monsoon months is particularly awe-inspiring. Local fish restaurants along the riverbanks near the barrage serve freshly caught fish—a regional delicacy that visitors should not miss. Popular preparations include fried river fish and fish curry made with local spices.

The Koshi Barrage is approximately 25 km from Pushkar Guest House in Simrahi and makes for an excellent day trip. The drive takes around 40 minutes via the main road. The best time to visit is between October and March, when the weather is pleasant and migratory birds are present. Whether you are interested in engineering marvels, natural landscapes or regional cuisine, a visit to Koshi Barrage offers a memorable experience during your stay at Pushkar Guest House.