India has expanded its surveillance of glacial lakes across the Himalayan river basins as the government strengthens preparations against Glacial Lake Outburst Floods, or GLOFs. The Central Water Commission is monitoring 2,485 glacial lakes with an area exceeding 10 hectares through satellite-based remote-sensing techniques, while a recent scientific assessment has placed 56 lakes in the “very high risk” category.
The latest figures were presented in a written reply to the Lok Sabha by Minister of State for Jal Shakti Raj Bhushan Choudhary on July 23, 2026. According to the reply, the monitored lakes are located across the Himalayan river basins associated with Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh, along with the Union Territories of Jammu and Kashmir and Ladakh.
The monitoring is carried out during the critical June-to-October period, when higher temperatures, monsoon rainfall, snowmelt and changing lake conditions can increase the threat of sudden flooding.
Monitoring Expanded From 902 to 2,485 Glacial Lakes
Until 2024, the Central Water Commission monitored 902 glacial lakes and water bodies larger than 10 hectares, based on an earlier inventory prepared by the National Remote Sensing Centre.
From 2025, the surveillance network was expanded using the Glacial Lake Atlas of Indian Himalayan River Basins published under the National Hydrology Project. The revised inventory covers 2,843 glacial lakes and water bodies, comprising 2,485 glacial lakes and 358 other water bodies.
Of the 2,485 glacial lakes situated within the wider Himalayan river basins connected to India, 681 are located within Indian territory. According to the Central Water Commission’s annual reporting, Arunachal Pradesh contains 324 of these lakes, followed by Ladakh with 179, Jammu and Kashmir with 76, Sikkim with 72, Himachal Pradesh with 17 and Uttarakhand with 13.
The larger basin-level inventory also includes lakes located in upstream areas beyond India’s borders because changes in such lakes may influence rivers flowing into Indian territory. Satellite monitoring allows agencies to observe changes in lake area, detect rapid expansion and identify lakes requiring closer scientific investigation.
56 Lakes Classified as Very High Risk
The National Disaster Management Authority, working with scientific and technical institutions, conducted a detailed assessment of 189 high-risk glacial lakes across the Indian Himalayan Region during 2025.
The assessment considered both the probability of a lake triggering an outburst and the possible consequences for people, settlements, roads, bridges, hydropower projects and other infrastructure located downstream.
Based on this evaluation, 56 lakes were placed in the very-high-risk category.
This classification does not necessarily mean that all 56 lakes are about to burst. It indicates that they require priority monitoring because a combination of unstable lake conditions and downstream exposure could produce severe consequences if an outburst occurs.
Scientists assess several factors while examining a glacial lake. These include the lake’s rate of expansion, surrounding slope stability, the condition of its natural moraine dam, the possibility of an avalanche or landslide entering the lake, water volume and the number of people and infrastructure located along the possible flood path.
The Central Water Commission has also developed criteria for risk-indexing glacial lakes according to their likelihood of failure and the scale of damage that a resulting flood could cause.
Why Glacial Lake Outburst Floods Are Dangerous
Glacial lakes commonly form when meltwater accumulates behind loose deposits of rock, sediment and ice known as moraines. Some of these natural barriers can become unstable as the lake grows.
An avalanche, rockfall, landslide, intense rainfall event or failure of the moraine dam can suddenly release a large volume of water. The resulting flood may travel rapidly through narrow mountain valleys, carrying boulders, mud, ice and debris.
Such events can damage villages, roads, bridges, military installations, communication networks and hydropower projects located many kilometres downstream.
The October 2023 disaster involving South Lhonak Lake in Sikkim demonstrated the destructive potential of a GLOF. The flood travelled through the Teesta basin, damaging settlements and infrastructure and contributing to the collapse of the Teesta-III hydropower dam.
Following that disaster, the Central Water Commission decided to review the design-flood calculations of existing and under-construction dams vulnerable to GLOFs. GLOF studies have also been made mandatory for new dams planned in catchments containing glacial lakes.
Early-Warning Systems Planned at Priority Lakes
The government has begun work toward installing Glacial Lake Outburst Flood Early Warning Systems at selected high-risk locations.
These systems may include automatic weather stations, lake-level sensors, cameras, satellite communication equipment, downstream monitoring stations and alert-distribution networks. Data from these instruments can help authorities detect unusual changes and issue warnings to downstream communities.
However, the government has clarified that no complete end-to-end GLOF early-warning system has yet been commissioned under the National GLOF Risk Mitigation Programme.
An end-to-end system must go beyond detecting changes at a lake. It must also transmit data reliably, analyse the threat, issue a warning through authorised agencies and ensure that the alert reaches exposed communities in time for evacuation.
This last-mile connection is especially challenging in high-altitude areas where harsh weather, unstable terrain, limited power supplies and poor communication networks can affect monitoring equipment.
₹150-Crore National Mitigation Programme
The National Disaster Management Authority is implementing the National GLOF Risk Mitigation Programme in Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh.
The programme was approved in 2024 with a total expenditure of ₹150 crore. Of this, ₹135 crore is to come from the National Disaster Mitigation Fund, while the four participating states are expected to contribute ₹15 crore.
The state-wise project allocation includes ₹45 crore for Arunachal Pradesh, ₹40 crore for Sikkim, ₹35 crore for Himachal Pradesh and ₹30 crore for Uttarakhand.
A total of ₹52.50 crore has been earmarked specifically for monitoring and early-warning systems. The programme also covers hazard and risk assessments, scientific expeditions, structural mitigation, community awareness and the strengthening of local disaster-response capacity.
Structural measures may include controlled water-release channels, strengthening of vulnerable lake outlets and protective works at selected locations. Non-structural measures include hazard mapping, evacuation planning, public-awareness programmes, regular drills and restrictions on unsafe construction in exposed areas.
Scientific Expeditions to High-Risk Lakes
Direct field investigation remains essential even where satellite images are available. Scientists need to study the depth of a lake, the volume of stored water, underwater terrain, moraine composition and the stability of surrounding slopes.
The NDMA, the Swiss Agency for Development and Cooperation and the Sikkim State Disaster Management Authority conducted multi-agency expeditions to South Lhonak and Shako Cho glacial lakes during 2023 and 2024.
These missions were intended to support detailed scientific investigation and help design suitable monitoring, mitigation and warning mechanisms.
India is also developing indigenous technologies for high-altitude glacial lake assessment. In June 2026, the Centre for Development of Advanced Computing transferred an autonomous glacial-lake profiling and risk-assessment technology suite to the Sikkim government.
The system includes autonomous survey equipment and software platforms capable of supporting lake profiling, bathymetric surveys and risk assessment. The transfer made Sikkim the first Indian state equipped to independently operate an indigenous end-to-end autonomous glacial-lake profiling capability.
From Mapping Lakes to Protecting Communities
The expansion of monitoring from 902 glacial lakes and water bodies to an inventory containing 2,485 glacial lakes represents an important improvement in India’s Himalayan disaster-preparedness framework.
The classification of 56 lakes as very high risk provides governments and scientific agencies with a clear set of priorities. The next stage will involve sustained field investigation, dependable monitoring equipment, operational early-warning systems and detailed evacuation plans for vulnerable settlements.
Protecting Himalayan communities will require cooperation among central ministries, state governments, scientific institutions, hydropower operators, armed forces, local administrations and residents.
Satellite monitoring can identify changing lakes, but the effectiveness of the programme will ultimately depend on whether scientific information is converted into timely alerts and practical action on the ground.
Reference Block
Government of India Ministry of Jal Shakti Lok Sabha Written Reply on Monitoring of Glacial Lakes and GLOF Risk Reply by Minister of State for Jal Shakti Shri Raj Bhushan Choudhary Date: 23 July 2026 Central Water Commission — Annual Report 2024–25 Monitoring of Glacial Lakes and Water Bodies in the Himalayan Region Press Information Bureau: https://www.pib.gov.in/PressReleasePage.aspx?PRID=2209732 Ministry of Home Affairs Disaster Response in GLOF Events National GLOF Risk Mitigation Programme, Monitoring and Early-Warning Measures Press Information Bureau: https://www.pib.gov.in/PressReleasePage.aspx?PRID=2150261 Central Water Commission Glacial Lakes and Water Bodies in the Himalayan Region — Monitoring Reports https://cwc.gov.in/glacial-lakeswater-bodies-himalayan-region Ministry of Electronics and Information Technology Indigenous Glacial Lake Monitoring Technology Suite Handed Over to Sikkim Published: 2 July 2026 Press Information Bureau: https://www.pib.gov.in/PressReleasePage.aspx?PRID=2280252
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