In a split vote, the Lewisville school board has approved plans for a new field house at Flower Mound High School but blamed town officials for adding $500,000 to the cost of the project.

"We're paying for a beautification project for Flower Mound," said school board president Carol Kyer, who called it a frivolous expense. "It doesn't have anything to do with education."

The $4 million field house will now cost $4.5 million because Flower Mound is requiring the district to bury overhead power lines at the site.

But Flower Mound Mayor Pro Tem Jean Levenick said the school district knew about the town's requirement to bury overhead lines and should have built the cost into the project.

"I'm sorry they didn't budget to comply with the ordinance," Levenick said. "But we have an ordinance that we need to uphold."

The dispute comes at a time when the school district is facing a projected $18 million budget shortfall. It also sheds light on the uneasy truce that often exists between municipalities and school districts but rarely spills over into a public discussion.

Before Monday's 5-2 vote, school board members Amber Fulton and Tom Ferguson sought to delay the vote to pursue legal options.

Fulton said the board must take a stand or continue to face this expense on other building projects. The district is planning to build two ninth-grade campuses in Flower Mound in the next five years.

Ferguson said $500,000 could be used to benefit students, including the replacement of musical instruments at three high schools.

But the majority of the board said delaying the project would only hurt students and voted to move forward with the 16,693-square-foot athletic building, which will provide more locker space for girls. It was part of the $697 million bond package approved by voters in 2008.

"I don't see any benefit getting into a spitting contest we can't win," trustee Fred Placke said.

Still, approving the added cost rankled trustees.

School board members pointed out that the overhead power lines in question serve an adjacent neighborhood, not Flower Mound High School. Power lines were buried when the school was built.

And, they said, the town didn't bury power lines when it built its Community Activity Center and has waived the requirement on other school projects, including the stadium at Marcus High School that was approved in July.

Since the lines at the Community Activity Center were in the right-of-way, the ordinance didn't require burying them, Levenick said. She didn't back waivers for either the stadium or the field house projects.

While Flower Mound High School students should be able to enjoy their new field house next year, the school board isn't going to let the issue of burying overhead power lines fizzle out.

Kyer said the board will see if state legislators can provide any relief for the district and said the board would consider a lawsuit as a "last straw."