A pre-feasibility report is an initial technical assessment of whether a project is viable.
Officials say the pre-feasibility exercise for the Siang project is not a final approval for construction.
Opponents want survey activities stopped and the affected communities consulted first.
Protests turned violent in Pasighat on October 23.
The project would be 11,200 MW.
Early on Friday, police reportedly fired tear gas at protesters near Geku, and four women opposing the project were injured, according to Outlook India.
After 5 pm, protesters in Pasighat blocked the highway and refused to disperse, and a magistrate and security forces tried to persuade them for two hours before tear gas was fired, according to the same report.
Protesters then allegedly pelted stones, injuring some police personnel and officials, and set fire to property, according to Outlook India.
The Pasighat office of the National Hydroelectric Power Corporation, the Pasighat police station and several government offices were set on fire or damaged, according to the reports.
Seven to eight police vehicles were set on fire or damaged, and the Deputy Commissioner specified that seven were burnt, according to Outlook India.
The homes of the BJP state president and two MLAs were damaged, and some property was reportedly taken away, according to Outlook India.
Eight protesters with minor injuries received first aid at a local hospital, according to the same report. The number of injured police personnel was not given.
The Deputy Commissioner said a magistrate ordered tear gas after protesters refused to disperse and that there was no baton charge, according to Outlook India.
The situation stayed tense until about 4 am on Saturday and was under control by the time of the Deputy Commissioner’s statement, according to Outlook India.
No arrests had been made in connection with the Pasighat violence as of Saturday noon, according to Outlook India.
Siang river banks at Pasighat (file image), Wikimedia Commons, CC BY-SA 3.0