The duck pond in Valley Gardens, Scarborough, has been contaminated due to light oil entering via the pond inlet.
The pond, near the Spa Bridge, has been polluted for a number of days, with several members of the public reporting it to the Borough Council.
Scarborough Borough Council have said they are aware of the situation and have officers monitoring it closely while investigating the cause of the problem.
A statement posted on the Council's Facebook page said: "We have been responding to a contamination issue this past week affecting the duck pond in Valley Gardens, Scarborough, (close to Spa Bridge). This involves small quantities of light oil entering via the pond inlet.
"Officers are monitoring the situation daily and have deployed containment booms and oil-absorbing pads on the water in several places.
"Investigations are ongoing as to possible sources of this contamination, meanwhile we are monitoring for signs of any wildlife affected by the pollution spill.
"We are grateful to members of the public for reporting this issue.
"When the source of the oil has been identified and stemmed a clean up operation can begin. Meanwhile please do not attempt to remove the contamination or the booms or textile pads and report any concerns such as oiled wildlife via Customer First."