Police quoted them $8,000 on the low end for a bill that typically runs between $500 and $1,000.
Waterfest concerts draw between 2,000 and 8,000 people depending on the popularity of the act.
Oshkosh Police and private security guards are always on site at the Leach Amphitheater.
"If there was some overtime or that sort of thing we would pick up those costs" explains John Casper, President of the Oshkosh Chamber of Commerce.
But now the bill could be a budget buster.
Oshkosh Police point to a schedule change for the potential increase.
For the first time Waterfest is holding some weekend concerts.
"I have never experienced a Saturday night Waterfest before so we are taking into consideration. What does a Saturday night bring versus a Thursday night element?" asks Sgt. Matt Harris, with the Oshkosh Police Department.
He goes on to explain "The big name that is out there Ted Nugent, July 26th that is a Saturday night".
Overtime is also a factor. The police department is being stretched thin, with a growing list of special events.
"On July 17th that is the Under the Sun Tour. That is Rock USA week so we also have some staffing concerns out there" Sgt. Harris explains.
The potential fees tie up money used to grow the event.
"It takes away from our abilities to put money back into promoting that event and booking acts not just for this year but for future years" says Casper.
Waterfest is not the only event having to re-think its budget.
Police quoted Sawdust Days $16,000 dollars for coverage this year.
The event paid $12,000 in 2013.
"We are trying to get more sponsors so we can continue to maintain our free status" says Sawdust Days Chairwoman Ellen Schmidt.
Ultimately everyone has the same goal.
"Making sure everybody is safe and has a fun time" says Sgt. Harris.
There are still a few open spots on the Waterfest schedule.
Oshkosh Police say once they are filled, they plan to meet with organizers to fine tune the budget.