Prime Minister Narendra Modi has asked the ministries of external affairs and water resources to find out why the water of Brahmaputra turned black and take remedial measures for it. This was conveyed at a high-level meeting chaired by the prime minister and attended by Union ministers Sushma Swaraj, Nitin Gadkari, Rajnath Singh, Arun Jaitely, Assam Chief Minister Sarbananda Sonowal besides others last evening, a statement issued by the Assam government said. Modi assured Sonowal that the Centre had already taken up the issue of Brahmaputra turning black seriously and even engaged the Central Water Commission to look into it and directed the Ministry of Water Resources to take remedial steps on a war footing. Considering the trans-national extent of the Brahmaputra, the prime minister also asked the External Affairs Ministry to take up the matter with the respective country to get into the root cause of the problem and find a positive solution. Swaraj maintained that her ministry had already contacted China and a pragmatic and exhaustive study was being undertaken to find the real cause, the statement said. The prime minister also asked the other ministries to work in synergy and directed the Ministry of Water Resources to ensure that scientific tests of Brahmaputra water are conducted to ascertain the physical and chemical composition of the river where it turned black. Sonowal informed the prime minister that the state government had directed the director general of Assam Emergency and Fire Services to collect water samples from 15 places from Jonai to Dhubri along the Brahmaputra and sent them to the Indian Institute of Chemical Technology, Hyderabad and IIT, Guwahati. Water of the Siang river in Arunachal Pradesh, which is called Brahmaputra in Assam, turned black from November-end. The water became muddy and cement-like apparently due to construction of a 1000-km tunnel by China to divert waters of the Brahmaputra which originates in Tibet. National Security Adviser Ajit Doval, Union Home Secretary Rajiv Gauba, Attorney General KK Venugopal, Director of Intelligence Bureau Rajeev Jain besides others attended the meeting.