About 900 have died and 3,000 are missing, according to official figures, in one of the worst natural disasters the country has had to deal with.

Many experts say the disaster is man-made and warn that it might not be the last to hit the fragile Himalayan ecosystem because of rampant and unplanned development in the region.

Environmentalists do not rule out the possibility of the flash floods having links to climate change. But they also say the construction of about 70 hydropower projects in the hill state, underground tunnels, roads, and the encroachments of riverbeds by buildings, coupled with deforestation, could have worsened the impact.

The primary blame, according to Himanshu Thakkar of the South Asia Network on Dams, Rivers and People, a not-for-profit organization, falls on the vast construction of hydropower projects on the rivers in the region.

“Throughout their life cycle, from construction, deforestation, blasting, mining, obtaining materials from the riverbed for construction, muck disposal, debris dumping, damming, altering hydrological cycle to allied activities like colonies, roads, infrastructure development, hydropower plants have a profound impact on geology and hydrology of the region,” he said.

Thakkar, who has been opposing the construction of dams in the country without cumulative environment impact assessments being conducted for these, said it would not be correct to determine the impact of any single project on an area when multiple hydro projects are coming up in a fragile ecosystem such as the Himalayas.

The Wildlife Institute of India in a 2012 report recommended the shelving of 24 projects in the upper Ganga region due to their potential high impact on the ecology. It said the projects affected nearly 10,000 hectares of land, with more than 3,600 hectares of forests being submerged.

Besides, the environment ministry has delayed deciding on a draft river regulation zone (RRZ) for over three years. The aim of the RRZ is to regulate construction and development near rivers, just as the coastal zone regulation is for regulating development near coastal and sea areas. “The RRZ notification could have helped in controlling infrastructure development like hotels and homes along the river,” said Thakkar.

India must evolve a right mix of ecological and growth and development balance, according to M. Shashidhar Reddy, vice-chairman of the National Disaster Management Authority. “Our policy should be such that everything should be subject to an environmental impact assessment. Lots of departments have learnt lessons and all of those need to be put together,” he said over the phone.

The carrying capacity of fragile ecosystems such as the Himalayas should also be considered, he said.

Thakkar said the expert appraisal committee for approving environment clearance to hydropower projects had not rejected a single one in the hill state since its inception six years ago.

Preparedness for such a disaster could have made a difference, said Sudhir K. Jain, director, Indian Institute of Technology, Gandhinagar. “Preparedness has a simple rule: has everyone done what they were supposed to do? And if they haven’t, then that is not acceptable,” he said over the phone.

Jain, who specializes in earthquake engineering, said India has a several areas that are prone to earthquakes, but cities are not being developed based on that. “We are not doing enough to ensure new constructions are safe. We must ensure that new constructions are as per correct procedure,” he said.

In the case of Uttarakhand, the landslide management and stormwater drain systems should have been better, he said.

India should evolve a pan-Himalayan development strategy based on each state’s natural resources, culture and traditional knowledge, said Sunita Narain, director general of the Centre for Science and Environment, an advocacy group. “We also know that climate change will exacerbate the vulnerability of this already-fragile ecosystem,” Narain said.