On Tuesday night, the Kosi, swollen by persistent rain in Nepal, swept away two of the three coffer dams — temporary 1,100-metre sandbag bunds — erected to facilitate work on plugging the August 2008 breach in the embankment at Kushaha on the Nepal border.

The river is now just 200 metre from its newly-repaired eastern bank. After the coffer dams collapsed, 51 of 55 gates of the Birpur barrage were opened to allow discharge

of 95,000 cusecs and ease pressure on the eastern (Kushaha) bank. The monsoon is perhaps a month away, and the Bihar government is struggling to complete strengthening the 1.7 km embankment.

Kosi Project engineers said the plugged embankment at Kushaha is still short of its desired height of 7.3 metres, and the crating of boulders and repair of five spurs at the site of the breach is yet to be completed. “The bank is about 6 metres high and boulders on its slope have also to be crated with iron wires to protect them from the Kosi’s ferocious waves,” said an engineer.

The engineer said the volatile political conditions in Nepal had been hampering work at the breach site. A team of engineers had had to leave Kushaha on Tuesday night after being threatened by a gang of anti-social elements.

Bihar Water Resources Minister Bijendra Prasad Yadav said fears raised by the collapse of the coffer dams were “false”. “The coffer dams were anyway temporary structures that were meant to be dismantled after the breach had been plugged. We are working on strengthening the newly-constructed bank,” Yadav said.

He added the state government had drawn the attention of the Centre to the obstacles being created in the repair work in Nepal. Workers from Bihar were not being allowed to carry out maintenance of banks in the restricted sanctuary area, the minister said.

River experts expressed concern over the Kosi maintaining last year’s course. Convener of the Indian River Network (Bihar), Bhagwan Pathak, told The Indian Express: “Despite three pilot channels in place, the river is flowing close to the eastern bank. The government must not pass the buck this year but coordinate with the Centre to carry out repair and maintenance throughout the flood season, until October.”

Pathak said the Central government should ensure that Nepal did not create problems for Bihar engineers. “Any lethargy will cause chaos again,” he warned.