The Greenway Foundation says it cannot afford to pay for its own patrols anymore.
Between this summer and last there have been more than 70 cases of car prowls, fights and trespassing. That number rises with the sun.
Christina Maesner does maintenance at the Greenway, but she doubles as security.
"Want to start a fight? We'll just call YPD," said Maesner. "We're not going to put up with this. This is a family environment."
She doesn't wear a badge or carry handcuffs, but she usually doesn't need to.
"If they see us, 9 times out of 10 that stop what's going to happen," said Maesner.
The Greenway used to pay people to patrol the trails but now the organization relies on volunteers in golf carts.
Sarg Hubbard is just one of seven parking lots spread between the Greenway's ten miles of trails.
Both YPD and Greenway staff say the "R" street lot is one of the hardest hit because it is more secluded and harder to get to.
Yakima Police say the majority of car prowls happen during the summer. They say even though it's hot, roll up your windows. Otherwise, you're making it too easy for thieves.