A dead otter was found in a cage along the Marina Promenade in the Kallang Basin on Wednesday (June 14).
A Public Utilities Board (PUB) cleaning contractor found the dead animal at about 11.40am that day, according to a statement by the agency on Friday.
PUB immediately informed the Otter Working Group of its finding. The dead otter has since been handed over to Wildlife Reserves Singapore for a post-mortem.
Investigations are ongoing.
Later that same day at about 5.30pm, PUB reservoir staff who were on their patrols caught a man setting up traps in the reservoir along Marina Promenade.
PUB said it will be taking enforcement action against the man under the Public Utilities (Reservoirs, Catchment Areas and Waterway) Regulations 2006.
It is an offence to trap any animal or carry out any act that might cause injury to the fauna in any reservoir in Singapore.
Anyone caught doing so may be fined up to $3,000.
Members of the public who spot any illegal acts at the reservoirs can call the PUB hotline at 1800-2255-782 and provide necessary details.