Millions of Indians have gazed in horror at videos showing 24 cheerful engineering students wading in a tranquil stretch of the Beas River in Himachal Pradesh last month and then being swept to their deaths as the waters around them surged.

The water was released from a dam upstream, apparently to deposit sand on the riverbed for easy mining. That release, and the drownings it caused, have been attributed to the “sand mafia,” a nexus of corrupt officials and the sand miners they let loot a basically free natural resource. An essential ingredient in cement, sand has seen its value soar along with the fortunes of India’s equally corrupt construction industry.

The construction boom in emerging economies — as well as land expansion in Dubai, Singapore and elsewhere — has caused the demand for sand to skyrocket. The United Nations Environment Program has warned that unregulated sand and gravel mining is irreparably damaging river and marine ecosystems as well as agriculture, and is causing increased vulnerability to rising sea levels.

The Supreme Court in India and its National Green Tribunal have ordered sand-mining operations — ranging from a couple of laborers with shovels to a major outfit using heavy equipment — to obtain clearances from the Ministry of Environment and Forests. State courts have also ordered regulation of sand mining.