Deep holes that left in Wagga's Duke of Kent Oval that could have injured sports players were discovered just before the cricket season resumes over the weekend.
Wagga City commercial operations director Caroline Angel said council staff believe the holes were created by 'treasure hunters' searching for different objects with the help of metal detectors.
"It's a very well-utilised oval and to to have that sort of damage, and more importantly putting people at risk, is fairly disappointing," she said.
"We would encourage people to be responsible in their looking for any things underground and respect that it is a heavily utilised oval and to ensure they operate within the code of practice for their activities."
Parks operations-sportsgrounds team leader Brian Cattell said council staff had found 10 holes, estimated to be about 10cm deep, in two locations on the oval, posing enormous risk to athletes or recreational users.
"This is a really dangerous practice," Mr Cattell said.
"These holes are quite deep and have the potential to cause a significant injury."
Ms Angel warned that digging for metal objects on sporting ovals or grounds across the region is strictly forbidden.
She said council staff were not sure when the holes were made but the activity was recent and the damage was discovered on Thursday or Friday.
Mr Cattell said the holes had been filled in.
"The Wagga and District Cricket Association competition actually starts this weekend, so we are relieved we found these holes in time, he said.
"They are almost impossible to see until you're right above them...making them even more dangerous."
Mr Cattell urged members of the public who believe someone is operating a metal detector on a council-operated facility is encouraged to phone Council's Call Centre on either 1300 292 442 or (02) 6926 9100.
"This dangerous activity will not be tolerated," Mr Cattell said.
"We are asking members of the community to be on alert...and to contact us if they notice anyone acting suspiciously on our sporting grounds or ovals."