Keller ISD is not happy about what it's about to do with taxpayer money. Almost $500,000 is being earmarked not for classrooms, teachers, or supplies, but trees.

That's right, trees. Hundreds of trees may have to be purchased, and Keller ISD may not have a choice. Keller ISD has no problem planting trees, the issue here is how many and how much taxpayer money should be used to do it.

A site looked like the perfect place for Keller ISD's new high school and elementary schools, the land was nearly vacant. "We bought a site that had four hackberry trees on it," said Mark Youngs, Keller ISD Deputy Superintendent.

But then the city of Fort Worth came calling. The site, you see, is technically in the city of Fort Worth, and Fort Worth has a tree ordinance.

What did that mean to Keller ISD? It meant about $500,000 in trees.

"We'd like to negotiate with them to get the price down, so we can spend the money on the school facility rather than landscaping," said Youngs.

The ordinance calls for nearly 500 trees to be planted on the elementary and high school sites. "It becomes an added expense that was completely unanticipated," said Youngs.

"It’s about sustainability. We only have one Mother Earth," said Richard Zavala, City of Fort Worth.

Richard Zavala oversees the Tree Ordinance in Fort Worth. He says trees are necessary to prevent storm water runoff.

"I think anybody doing development is going to look at various costs and this is one of those," said Zavala.

But across the Metroplex, not all school districts pay up. Arlington has a tree ordinance, but an Arlington ISD spokesman tells us: "It would not be fiscally responsible for the district to comply."

That spokesman says their attorney maintains government entities like school districts are exempt.

Keller ISD is consulting with attorneys about future options, but for now administrators say they have little choice but to start digging.

"We think the numbers behind the ordinance are excessive and strong. We think they require too much," said Youngs.

A Fort Worth spokesman sent an email. It concedes school districts are exempt, but goes on to claim, essentially, everyone's just chosen to cooperate.

We passed that statement along to Keller's Deputy Superintendent. He was surprised, saying: Fort Worth's never told Keller ISD its cooperation was voluntary. Instead they felt threatened, believing Fort Worth may halt the whole project if they don't play ball.

E-mail chawes@wfaa.com