ESL not working well in California

Nearly 60% of English-language learners in California's high schools have failed to become proficient in English despite more than six years of a U.S. education, according to a study released Thursday.
In a survey of 40 school districts, the study found that the majority of long-term English-language learners are U.S. natives who prefer English and are orally bilingual. But they develop major deficits in reading and writing, fail to achieve the academic English needed for educational success and disproportionately drop out of high school.

So it's not immigrants. It's native-born children of immigrants, who come from Spanish-speaking homes and themselves speak English just fine but can't read or write it well.

My guess is it is because we teach them to read in English, when it is their second language, even if they speak it well enough. There is research I don't have at hand right how showing that little kids with non-English home languages learn to read English better if they learn to read first in their native language and then transfer that skill to their second language rather than trying to develop the skill in the second language, where they have to translate as they learn to read.

I wonder how well these kids read and write in Spanish.