California's prisons are severely overcrowded, making them dangerous and unhealthy. Recidivism is on a rise and there seem to be little hope for resolution -- except spending millions to build more prisons. The other answers, such as rethinking a failed 3 Strikes policy, which has compounded the problem, is politically unthinkable, though ultimately necessary.
Steve Lopez writes in his Column One essay in the LA Times about this problem and offers some possible solutions -- one has to do with dealing with the issue of mental health. With so many inhabiting the prison population suffering from mental illness, and with little effort to resolve these problems, it's no wonder that the prison population continues to rise. Take a look at the column!