Twenty-four students from a Hyderabad engineering college and a tour operator were washed away in the Beas river last Sunday. Eight bodies have been found so far.
"We deployed side scan sonar to capture pictures of the riverbed to locate the bodies. It showed good images (of the riverbed) but no bodies were traced," Jaideep Singh, commanding officer of the National Disaster Response Force (NDRF), told IANS.
Almost 10 km of the river stretch from the Pandoh dam to the upstream was scanned using the echo sounder.
In the first four days of the operation, eight bodies were recovered. However, no body has been traced in the next three days.
Most of the bodies recovered, officials said, were either trapped under the rocks or buried in the riverbed silt within a three-km radius of the accident spot at Thalaut on the Chandigarh-Manali National Highway No.21.
"We can now go for the possibility to open the floodgates of the Pandoh dam so the water level in the reservoir is reduced drastically and the bodies, if trapped in boulders or stuck in the slit, come to the surface," Telangana Home Minister Nayani Narasimha Reddy, who is camping here, told IANS.
He said some parents of the missing students have apprehensions the bodies might wash away further if the water is allowed to go downstream.
"But any decision in this regard will be taken with the consent of the parents," he added.
Official sources said the parents were opposed to the decision to open the floodgates.
The district administration Saturday sought the consent of about 25 parents and family members of the missing students, camping here since Monday, to allow the administration to open the dam floodgates so the bodies, if stuck in the reservoir, could be fished out.
Official sources said the depth of the reservoir is between 30 and 50 feet.
"We can easily trace the bodies if they are further washed away with the release of water from the dam, as the river stretch is narrow downwards," Deputy Commissioner Devesh Kumar, coordinating the search operation, said.
The water level in the three-km river stretch near the accident spot was lowered Saturday for the first time but there was no major achievement in locating the missing students.
Over 550 rescue workers, comprising about 50 divers of the NDRF, the army, the navy and the ITBP, are involved in the search operation, focusing on the 15-km-long downstream stretch of the river from the Larji hydropower project dam to the Pandoh dam.
The tragedy occurred when a group of students from the V.N.R. Vignana Jyothi Institute of Engineering and Technology were swept away last Sunday when water was released into the river without warning from a nearby 126 MW Larji hydropower project. The students were on an excursion to Manali.
Police have registered a case against the Larji hydropower project authorities for causing death by negligence and endangering the life of people.
State Industries Minister Mukesh Agnihotri, who visited the accident spot Sunday, directed the public works and forest departments to close all the link roads constructed to carry out illegal mining activities in the Beas river within seven days.