Though Superintendent Carl Harris budgeted 54 percent more money this year for fuel than for the previous year, district officials say they still could see a $700,000 funding gap between what they'll spend and the state's reimbursement, said Scott Denton, the schools' director of transportation. District officials estimate they'll spend about $2.75 million on diesel fuel alone for the 2008-09 year due to cost increases -- the likes of which all of the state's school districts are feeling.

Denton briefed the school board Thursday in a committee meeting about strategies to increase fuel efficiency. When school bus routes are released later this month, parents could see slight changes in their stops, he said.

For example, Denton said, instead of hitting all corners of a winding subdivision, a bus might just stop at a more central location in the middle that everyone can walk to.

The district will more strictly enforce its policy against idling engines and could also merge some populations of students. For example, students with disabilities, who typically ride in separate buses with adult monitors, might have to share a few miles of their route with mainstream children.

Middle schoolers who live in rural areas could see some high schoolers on their buses to prevent the district from having to send two separate buses to rural areas, Denton said. Older students might also use the city's bus system for after-hours transportation, as some students from an alternative high school at Northgate Mall already have done this year, Denton said.

None of the changes will be drastic, Denton said, because he doesn't want to compromise safety or roil parents. "Experience has taught me that if you want to change something, you do want to go a little bit slow," he said.

One change Denton says he won't consider is adhering to the state law that says school districts can require students who live within 1.5 miles of the school to walk. The idea would likely be opposed by most parents, he said.

The district uses about 650,000 gallons of diesel fuel a year, Denton said.

In addition to the record high costs of diesel fuel, for which the district pays more than $4 a gallon, Denton said he expects that student ridership will increase 20 percent to 30 percent. He attributes that to increased enrollment and fewer parents opting to burn gas money on daily commutes to school when students can ride the buses for free.