Hydropower, the silent anchor of India’s electrical grid, may face a severe supply threat this fiscal year, as a weak monsoon fails to top up depleted reservoirs. The likely shortfall comes at a precarious time for the country, where power demand has already shattered records and is projected to climb even higher in the coming months.
The India Meteorological Department (IMD) expects El Niño to cast shadow over this year’s monsoon, and has accordingly revised its rainfall forecast to 90% of the 50-year average. El Niño had taken a toll of 12% on hydropower generation in 2015-16.
Given the and the state of reservoirs, this year’s hydropower generation may be around 10% lower than last year’s, said AK Singh, adjunct professor at IIT Roorkee and former hydropower general manager at NTPC, the country’s largest thermal power producer. “This is in the wake of an expected monsoon deficit as well as a high base. Reservoir levels are already low. Usually, during the monsoon, they attain full reservoir level (FRL). But this year, most of the major reservoirs may fail to be anywhere near it,” Singh said. According to Singh, lower reservoir levels also mean weaker force on the turbines, resulting in lower power generation.
Weaker monsoons have impacted hydro generation in the past as well, said Ankit Jain, vice-president and co-group head, Icra Ltd. “FY2024 was a bad monsoon year wherein generation had declined by more than 15% on a year-on-year (y-o-y) basis. Also, FY26 was a better year with about 12% growth on a y-o-y basis. This year too, we may see a fall in generation owing to weak monsoon. However, its impact remains to be seen, as thermal capacity, which is currently running at around 70% PLF, can ramp up,” Jain said.
Hydropower wields an outsized influence in India’s power puzzle, despite accounting for only 10% of its total power capacity. That’s because unlike solar power that winds down by sunset and thermal stations that take time to power up, hydropower can be turned on and off at will, helping keep the grid stable.
India’s 166 reservoirs currently hold 54.726 billion cubic meters (bcm), or 29.81% of their total live storage capacity, lower than last year’s 58.303 bcm. Of these, 20 reservoirs form part of hydro-electric projects. In half of them, water levels are less than or equal to last year’s levels, indicating less water to generate electricity.
The reservoir at India’s largest hydroelectric project in Maharashtra’s Koyna is at 11.14% compared to last year’s 18.80%, and the 10-year average of 15.93%. The level in Uttarakhand’s Tehri hydro project is currently at 0.45%, compared to last year’s 1.21% and the 10-year average of 3.33%. The level at Madhya Pradesh’s Okmakareshwar project is less than half the year-ago levels, but above the 10-year average of 18.27%.
Reservoir woes
RP Goyal, former director (finance) at NHPC Ltd, India’s largest hydropower producer said: “There may be some impact due to a weaker monsoon; however, the major impact would be felt in the reservoir-based projects in central India. NHPC has two joint venture projects, Omkareshwar and Indira Sagar, which may face impact.” Goyal added that most NHPC hydropower projects in Himachal Pradesh or Jammu & Kashmir are built on snow-fed rivers, which should not suffer from weaker monsoons, and may instead benefit from higher snow melting.
In FY26, India’s hydropower generation was at 167.20 billion units, about 10% of the overall electricity generation of 1,847.94 billion units. Power demand has already hit a record of 270.8 gigawatt (GW) and may surpass this level over the next few months.
“In hilly regions, rainfall, springs, and glaciers are the primary sources of water. During summer, glaciers contribute nearly two-thirds of the water flow in hilly areas. Low reservoir levels is likely to affect hydropower generation in mountainous areas, while also impacting irrigation and drinking water supply in the plains,” said Iftikhar A. Drabu, a Srinagar-based civil engineer who has worked on hydropower projects, including Uri, Kishanganga, and Dulhasti.
Spread of rains
However, Abhay Kumar Singh, president, Indian National Hydropower Association (INHA) said that weaker monsoon may not be a major concern, but the spread of rains over a long period needs to be watched.
“Heavy rains sometimes become counterintuitive as it leads to heavy silt formation, requiring halt in turbine operations and desilting. Weaker monsoon per say is not an issue, but what is required is a good spread of rains from June to September end or October. Even lesser quantum of rains, which is evenly spread during these months are adequate for good power generation,” Singh said.
During monsoon, projects in mountainous regions built on rivers usually go for desilting. Since India kept the Indus Water Treaty in abeyance, India has been undertaking on a regular basis of the projects in Jammu & Kashmir on rivers flowing through Pakistan. Desilting is carried out by releasing a large volume of water from a reservoir to clear accumulated sediments at least once a month during the monsoon season. NHPC is already carrying out operation and maintenance in its projects in Jammu & Kashmir.
Queries mailed to the Union ministry of power, and hydropower leaders NHPC and SJVN remained unanswered till press time.
A former executive with state-run Grid Controller of India, the national power grid operator said: “A drop in hydro power generation would be a concern if the installed capacity is higher than the year ago period.” Currently, India’s hydro power capacity stands at 51.41GW, compared to 47.72GW in the year ago period.
India has accelerated developing hydro projects after keeping the Indus Water Treaty after the terror attack in Pahalgam. India plans to achieve 500GW of non-fossil capacity by 2030, including about 70GW of hydro power.