SIOUX FALLS, S.D. - School districts with fewer than 600 students are finding it hardest to meet the requirements of the federal No Child Left Behind law, a new report says.

Smaller districts are having a hard time attracting highly qualified teachers, according to the study by the Government Accountability Office. The teachers often must teach multiple grades or subjects and feel isolated from big libraries, professional development and programs for special-needs students, the report said.

Declining enrollments mean less state aid while higher standards require more resources, the report said. Also, special-needs and disadvantaged students make up a bigger percentage of the students in smaller districts.

Sens. Tim Johnson, D-S.D., and Kent Conrad, D-N.D., had asked for the report. Conrad said nearly a third of the country's public schools are in rural areas.

"The bottom line is that rural schools have unique needs that must be addressed," Conrad said.

Government Accountability Office researchers visited several states, including Isabel and Todd County schools in South Dakota. North Dakota, Nebraska and Montana were visited, and Iowa, Kansas and Wyoming educators were surveyed by telephone. Districts in several other states also were included.

About 85 percent of the 1,200 rural superintendents nationwide who received mail surveys filled them out.

Centerville Superintendent Doug Voss said his district has tested well the past two years but has lost students. Along with those students, the district has lost the Title I money earmarked for educating children from low-income families.

Without some special grants from another program, "I don't know what we would've done," Voss said. "I just don't know where we would have been."

Title I, the single-largest federal program supporting K-12 education, funneled almost $12 billion to about 90 percent of districts nationwide in 2003.

Nationwide, 13.8 percent of rural children live below the poverty line. But in South Dakota, it's 19.8 percent. South Dakota also is 15th in rural minority students and 50th in pay for rural teachers.

"Our percentage of special-education students at Centerville is 19 percent, above the state average," Voss said. "I'm surprised we continue to stay off alert status, but I think it's just a matter of time."

Nancy Duncan, principal of Anne Sullivan elementary school in Sioux Falls, said she believed so strongly in her teachers and students that she filed an appeal over her school's test scores.

"Some of the things just don't make sense," Duncan said. "Our teachers understand that, people here understand that, and they can't see why others don't."

The system needs reworking, Johnson said. "I don't see a wholesale reversal. … But I think we need to take a look at how we're evaluating different subgroups," he said, referring to students with learning disabilities, limited English skills and other special needs.

No Child Left Behind is "overly rigid and underfunded," Johnson said, calling it "embarrassing" that federal money again will come up about $9 billion short this year.

Conrad said he has asked the GAO to brief the Senate Rural Education Caucus on Thursday.