SALT LAKE CITY -- Educating the children of illegal immigrants in Utah cost $54.9 million to $85.4 million in the 2005-06 school year, a wide range that reflects the difficulty of counting the population, according to an audit released Tuesday.

Some lawmakers want the federal government to reimburse the state for the costs it incurs as a result of illegal immigration, although a bill by Rep. Karen Morgan, D-Cottonwood Heights, directing the Utah attorney general to find a way failed earlier this year.

Illegal immigration is a contentious issue in Utah, where the state's growing economy has made it an attractive place for those seeking work.

Many lawmakers in the Republican-controlled Legislature claim illegal immigrants are putting a strain on state services. They have chastised Utah's congressional delegation for not doing more to stop the flow across the nation's borders.

Utah spent about $3.5 billion on public education in 2005-06, including $500 million from the federal government.

Exact figures on the number of children of illegal immigrants aren't available, but the audit estimates there are 10,714 to 16,627. It's unclear how many are in the country legally. Children born here are U.S. citizens, even if their parents are not.

The audit based the estimates on research by Jeffery Passel of the Pew Hispanic Center in Washington, D.C.

The audit looked at five school districts -- Granite, Ogden, Provo, Salt Lake City and Tooele -- to make a statewide estimate on costs.

On average, the audit found school districts spend about $500 more educating the children of illegal immigrants in high school and about $140 more in kindergarten through eighth grade.

That is based on the assumption that children of illegal immigrants are likely to use services aimed at low-income families and also take classes to improve their English.

It's unclear what lawmakers will do with the audit's findings, which were presented at a committee hearing Tuesday.

Utah is required to educate all children, regardless of immigration status, and can't ask if they are legal residents.

"My assignment on (the education committee) is to make sure we have adequate funding for education," said Sen. Margaret Dayton, R-Orem, who requested the audit.

Utah spends less per student than any other state. There would be millions more available if the children of illegal immigrants weren't in school, Dayton said.

Rep. Christopher Herrod, R-Provo, said the audit is useful in setting a baseline. Federal policies are failing, he said, if more children of illegal immigrants are enrolled next year.

In response to the audit, state Superintendent Patti Harrington said teaching students English, particularly poor ones, is critical to their success.

"It is not universally true, but more the norm than not, that students living in poverty will need additional help, specifically in language development," she wrote. "Thus, additional time and/or intensified or small group instruction is needed to help students develop vocabulary and comprehend language and meaning."

That costs extra money, said Harrington, who hopes the audit may help in acquiring more funding.

Morgan said she will sponsor another bill next year that would direct Attorney General Mark Shurtleff to report on how Utah can recover money spent as a result of illegal immigration, including a possible lawsuit.

"The federal government requires the state to provide certain services for illegal immigrants and these can be quite expensive," she said. "They need to help us pay for those."

Hispanic advocates are calling for a comprehensive study that compares the cost of public services used by illegal immigrants to the contributions they make to Utah's economy.

They point to a 2006 study by the Texas Comptroller's Office that found illegal immigrants received $1.16 billion in state services but paid $1.58 billion in taxes.

"By not looking at that, we are really only getting one half of the equation," said House Minority Leader Ralph Becker, D-Salt Lake City.

Herrod said the Texas study didn't include local costs for law enforcement and health care. He wants the federal government to strengthen immigration laws or pick up the tab for having illegal immigrants here.

In Washington, lawmakers are discussing a plan to grant legal status to the estimated 12 million illegal immigrants already in the U.S., allowing them to seek permanent legal residency or citizenship.

They would be subject to a $5,000 fee and fines, and the heads of households would have to return to their country of origin temporarily.

This story appeared in The Daily Herald on page A1.