Kiama Municipal Council has fined Jamberoo Action Park $6456 after a dam was breached, spilling silt and mud into a nearby creek.
The park's owner Jim Eddy said the incident occurred eight months ago when the recreation park was building a new dam for water storage.
Mr Eddy said the site was that of a smaller dam which had been on the property "since the beginning of time".
"We had to make it bigger to increase our water storage, but first we had to release the water from the old dam to be able to build the new wall," he said.
The release was occurring slowly, but increased overnight.
"The flow from the old dam disturbed sediment in the creek and discoloured the water," he said.
"I have always said if we do anything contrary to the environment we must fix it ... we had four labourers go down this creek with brushes, brooms and buckets cleaning the rocks until any hint of discolouration was removed."
Council staff said because the incident had occurred during a relatively dry period, the water pollution did not have a severe impact and did not reach the Minnamurra River.
Kiama Mayor Brian Petschler said while the dam breach was contained to an extent, there were breaches of the Protection of the Environment Operations Act and the Environmental Planning and Assessment Act and councillors decided to proceed with a penalty notice.
Mr Eddy said the park would pay the fine and move on.