Periyar’s famous lake isn’t natural. The British built a dam in 1895, and the water it holds still fuels one of India’s longest-running interstate fights.
🐘 Periyar National Park, at a glance
A wildlife park built entirely around a 19th-century engineering project
The dam
Mullaperiyar Dam, completed 1895, across the Periyar River.
National park
Core of 350.54 sq km, inside a 925 sq km reserve.
The lease
1886 agreement, 999 years, still disputed by Kerala and Tamil Nadu.
2026 update
Parliamentary panel reviewed the dam’s safety at Idukki, June 2026.
On this page
A Lake With No Natural History
A Lake Made by a British Dam
Periyar National Park lies in the Idukki district of Kerala, in the Western Ghats, near the town of Thekkady. Its central feature is an artificial lake, formed when the British finished the Mullaperiyar Dam across the Periyar River in 1895.
True or False: The lake at the heart of Periyar National Park was created by a dam, not a natural water body.
- 1934: sanctuary begins as the Nellikkampatty Game Sanctuary, set up by the Maharaja of Travancore.
- 1978: declared a Project Tiger reserve.
- 1982: its 350.54 sq km core, inside a wider 925 sq km protected area, becomes a national park.
- 1991: also declared an Elephant Reserve.
Same river, two names: the park and its lake are both named after the Periyar River — Kerala’s longest river — which the Mullaperiyar Dam impounds.
Watching Wildlife From the Water
Tigers, Elephants, and Boat Safaris
The reserve holds at least 40 tigers, but it’s better known for its elephants. Large herds gather along the lake’s edge to drink, especially in the dry season, when water outside the reservoir runs short. Boat safaris on the lake are the park’s signature visitor experience — vehicles can’t reach much of the shoreline, so animals behave more naturally than in many drive-through parks.
True or False: Wildlife sightings on Periyar’s boat safaris stay roughly the same across all seasons.
- Jungle treks: guided walks with trained local guides, run as an alternative to the boat safari.
- Reformed guides: many guides are former poachers, now employed through community eco-tourism programmes.
- A conservation model: this reformed-poacher scheme is often cited as a genuine success story in community-based conservation.
A Western Ghats Hotspot
Forest and Wildlife
Periyar’s vegetation ranges from tropical evergreen forest to moist deciduous forest and open grassland. This mix reflects its place in the Western Ghats biodiversity hotspot. Thekkady, the main gateway town, sits within Kerala’s cardamom hill region. Tea, coffee, and spice plantations surround much of the park. These plantations act as an informal buffer between farmland and the core forest.
- Other big mammals: gaur (Indian bison), sambar deer, wild boar, and the Nilgiri langur.
- Rare species: the Nilgiri tahr in higher terrain, and occasional lion-tailed macaques.
- Birds and more: over 260 bird species recorded, plus a wide range of reptiles and amphibians.
- The reservoir’s own life: several fish species, some introduced after the dam was built, support local fishing cooperatives licensed to operate on the lake.
A River That Doesn’t Water Its Own State
A West-Flowing River Trap
UPSC once asked how many of four rivers — Sharavathi, Periyar, Mandovi, and Daman Ganga — are west-flowing rivers. The answer is all four: they’re Western Ghats rivers that drain into the Arabian Sea. The Periyar is the very river that forms the lake at the heart of this national park.
The twist: water from the Mullaperiyar Dam is actually diverted east into Tamil Nadu, not down Kerala’s own western slope — the opposite of what the Periyar’s west-flowing course would suggest.
A Colonial Lease, Still Contested
A 999-Year Lease and a Live Dispute
The Mullaperiyar Dam was built under an 1886 agreement. The deal was between the Maharaja of Travancore and British India. That lease handed the site to what is now Tamil Nadu, for 999 years. Tamil Nadu still operates the dam and draws its water. Kerala only receives rent under the lease. Kerala has long argued the dam is unsafe. The dam is now well over a century old, past its working life.
True or False: The Mullaperiyar dam dispute between Kerala and Tamil Nadu is still an active, unresolved legal case.
Think it through, before reading on. Periyar’s boat safaris are a calm, popular tourist draw. Why does the very same dam that makes them possible also sit at the centre of one of India’s longest interstate disputes?
Show the explanation
The lake tourists enjoy exists only because of an 1886 lease. Under that lease, Tamil Nadu still operates a 19th-century dam. It diverts the Periyar River eastward for its own water needs. Kerala hosts the dam, and carries the risk if it fails. But Kerala doesn’t control the dam, and gets none of its water. A structure built for one purpose, irrigation in Tamil Nadu, ended up shaping a Kerala wildlife park a century later. The safety and control questions behind it are still unresolved.
Still Under Review
Parliamentary Panel Reviews the Dispute (2026)
In June 2026, the Parliamentary Standing Committee on Water Resources met at Idukki, Kerala, to review the ongoing Mullaperiyar dam issue. Committee Chairman Rajiv Pratap Rudy said discussions centred on two things: the dam’s safety, and guaranteeing water availability for both states. The panel is weighing technical and legal arguments from both Kerala and Tamil Nadu before submitting recommendations — keeping the dispute this article covers very much a live issue.
Quick Q&A
Q: Where is Periyar National Park?
A: Idukki district, Kerala, in the Western Ghats near Thekkady.
Q: Why does the park have a lake at all?
A: The British-built Mullaperiyar Dam, completed in 1895, impounds the Periyar River to form it.
Q: Who actually operates the dam today?
A: Tamil Nadu, under an 1886 lease running 999 years; Kerala receives rent but disputes the dam’s safety.
Q: What made Periyar’s community eco-tourism model notable?
A: Many of its guides are former poachers, now employed to lead treks — a widely cited conservation success story.
MCQ on Periyar National Park
Try 5 practice questions on Periyar National Park.
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