Step 1: Recall India's key environmental legislation timeline.
The Wildlife Protection Act came in 1972, the Forest Conservation Act in 1980, and the Environment Protection Act followed later as an umbrella law.
Step 2: Connect the trigger event.
The Environment Protection Act was enacted in direct response to the 1984 Bhopal gas tragedy, which exposed major gaps in India's environmental regulatory framework.
Step 3: Pin down the year.
Passed by Parliament to give the central government comprehensive power to protect and improve the environment, the Act came into force in 1986.
\[ \boxed{1986} \]