The American Civil Liberties Union on Wednesday charged that more than a quarter of the school districts in California, including three on the North Coast, fail to provide English language instruction to all students who need it.

The ACLU said more than 20,000 students in California did not receive any language instructional services, as mandated by state and federal laws. The organization threatened to sue the state Department of Education if the situation isn't remedied.

Windsor, Geyserville and Ukiah have between 9 and 12 percent of English learners not being served, according to the report.

The numbers surprised local educators Wednesday.

"It's befuddling. We make services available to all of them," Geyserville superintendent Joe Carnation said. "As far as I know, every eligible youngster is being served."

The ACLU provided statistics from the Department of Education that show about 10 percent of Geyserville Unified School District's 132 English learners did not receive services in 2010-11.

In the Ukiah Unified School District, more than 12 percent of the 1,469 students who needed English language instruction did not receive it, according to the report.

In the Windsor Unified School District, the report stated about 9 percent of its 1,062 English learners lacked the requisite instructional services.

Maria Armstrong, Ukiah's director of curriculum and instruction, said she was confident "that we are providing appropriate programs for our students."

She detailed a number of programs tailored to English learners, who are defined as children who do not speak English, or whose native language is not English, and cannot perform ordinary classroom work in English.

Armstrong said non-native speakers are provided with appropriate classes, as well as supplemental after-school programs and even tutoring at home if necessary.

"We're focused on trying to fill the gaps," she said. "We know how critical that language development is."

Windsor's superintendent Tammy Gable said she needed to get more information on the statistics cited by the ACLU.

"We have quality programs and services for English learners," she said. "My expectation is all students are served appropriately. We'll investigate and see."

The ACLU said the statistics came from numbers reported to the state by the districts themselves.

"Repeated studies by the California Department of Education, the state Board of Education and the California Legislature documented that this student population has gotten short shrift from our schools and that the consequences have been dire," the report said, adding that those students are most at risk of dropping out and experiencing persistent academic failure.