It seems California is simply redirecting many offenders from state prisons to local prisons, in order to comply with the Court’s mandate:

Ordered by the United States Supreme Court to reduce severe overcrowding in its prisons, California began redirecting low-level offenders to local jails last October in a shift called realignment. Its prison population, the nation’s largest, has since fallen by more than 16 percent to 120,000 from 144,000; it must be reduced to 110,000 by next June.