The dumping of household waste has been blamed for overflowing bins at King George V Recreation Ground in Bushey.
This follows an investigation by council staff and contractors, after local councillors received persistent complaints from park users about litter piling up on the ground around the full bins.
They found that the bins are regularly being filled with sacks of largely domestic refuse.
Efforts are now being made to identify those responsible.
Lib Dem Bushey Park councillor Maxie Allen said: “It seems that a small number of people are placing their excess household rubbish in the King George bins. This is not permitted, and counts as fly tipping.”
Hertsmere Borough Council is introducing new letterbox-style bins at the park, which are harder to fill with sacks.