MILWAUKEE COUNTY, Wis. (CBS 58) -- Some Milwaukee County Zoo Zoo Pass holders are upset after a recent change. 

Zoo Pass holders have been told this year that they will have to buy a ticket to get into the Boo at the Zoo event in October. 

Laura Temke of Wauwatosa has a Zoo Pass. She says her kids love the zoo, but they won't go to Halloween-themed event this year. She's upset she was only recently told about the change. 

"I understand budgetary constraints, having to think forward, maybe even having to change for some of the events just because of how popular they've gotten. But the way they went about it was just horrible. Short notice, you know, we renewed our membership in December of 2017, it would have been nice to know at that time," said Temke. 

The Milwaukee County Zoo sent CBS 58 a statement saying they've re-imagined Boo at the Zoo to "better manage the popularity of the event for guest safety and traffic flow."