MULLAPERIYAR DAM · CASE REFERENCE UNRESOLVED · SUPREME COURT OF INDIA
Built
1887–1895
Lease term
999 years
Current cap
142 ft
Status
Disputed

A colonial lease. A live disaster question. Still unresolved.

In 1886, a Travancore king signed a 999-year lease for a river, and reportedly said he was doing it "with my blood." The masonry dam built on it has no cement, no steel, and sits above millions of people. The dispute over its safety has run in the Supreme Court since 2001.

Attributed to Maharaja Moolam Thirunal, 29 Oct 1886. Never traced to a primary source, but repeated for 140 years regardless.
See what's at risk Read the engineering
Mullaperiyar Dam, downstream face: masonry gravity dam, 176 feet high
EXHIBIT A: DAM FACE, DOWNSTREAM SIDE1895–PRESENT
SIGNED 29 OCT 1886YEAR 140 OF 999859 YEARS REMAIN
131 yrs
Old, no cement, no steel
176 ft
Height above foundation
3.5–10M
People downstream, disputed
Idukki, Kottayam, Ernakulam, Kochi. Not an abstraction.
Zone III
Seismic classification

Recent developments

UPDATED SEPTEMBER 2026

The record, in six parts

RED = SAFETY-CRITICAL READING
01 / ORIGIN

History & Origins

A famine, a king pressured into a 999-year lease, and a tunnel bored through a mountain by hand.
02 / SPEC

Engineering

Lime-surkhi mortar, no cement, a gravity-fed tunnel. How it actually works, in specs and diagrams.
03 / SUIT

The Dispute

Kerala v. Tamil Nadu: the 1970 agreements, the 2014 judgment, and both states' cases, argued fairly.
04 / RISK

Safety Debate

The surveys, the cracks, the seismic studies: what the experts actually found, and where they disagree.
05 / MODEL

If It Breaks

The only real hydraulic study ever done, against the viral claims that don't hold up.
06 / SITE

Culture & Reserve

999 hearths lit each January, a tiger reserve, a festival on a sandbank, a banned film.
SCENARIO FILE, NOT A PREDICTION

What actually happens if it fails?

The only real hydraulic study ever done puts water at the Idukki reservoir edge in 128 minutes, not the "45 minutes" you'll read elsewhere. And the widely-cited "35 lakh deaths" figure traces to a report that substituted Google Earth imagery for a real topographic survey. We separated the modeling from the noise.

Read the dam-break scenario →
KERALA'S CASE

"We own the land. We live with the risk."

An 1895 dam the state's own scientists have flagged for 45 years, and still can't get replaced, despite offering to fund a new one outright.

TAMIL NADU'S CASE

"Every court-appointed expert has certified it safe."

Five districts, a century of irrigation, and a lease Kerala's own government re-signed in 1970, validated twice by the Supreme Court.

Read both cases in full, argued at equal strength →

About this reference

Wide view of the Periyar reservoir, the lake formed by the Mullaperiyar Dam since 1895
The Periyar reservoir, formed when the dam first filled in 1895CC BY 3.0, Wikimedia Commons

This site is an attempt at a genuinely balanced, source-checked reference on Mullaperiyar, a subject where most writing online picks a side: Kerala's safety anxiety, or Tamil Nadu's certainty of vindication. Every page here separates what's well-corroborated from what's disputed or unverified, names who is making each claim, and flags where sources disagree rather than silently picking one.

A few examples of that discipline, since it's easy to claim and hard to demonstrate. The "35 lakh deaths" figure that circulates in Kerala advocacy material is tracked to its original source and its methodology examined, not just repeated or dismissed. Both Tamil Nadu's and Kerala's legal and safety arguments are presented at their strongest, with an honest note on where each is weaker. And where our own research hit a dead end, whether that was an unverifiable quote or a document we couldn't access, we say so plainly rather than smoothing it over.