About 2,000 Aadhaar cards have been dumped near the Mulliyaaru bank in Tiruvarur district, according to revenue officials.
The cards meant for distribution to the owners had not been apparently delivered by the post office concerned, the officials said.
Some of the local people in Thiruthurapoondi managed to get their Aadhar card from the dump, they said.
The cards, bundled in jute bags and abandoned, were found by the children playing in the riverbed.
The revenue officials rushed to the spot and recovered the cards.
The cards belonged to the residents of Kattimedu, Aathirangam, Vadapathi and Sekkal villages, the revenue officials told newsmen. The cards had been printed two years ago, the officials said.
The people of the area would have got the government scheme benefits by quoting the application number.
A case has been registered on a complaint from the village administrative officer, the police said.