SAN FRANCISCO -

In the midst of a prolonged drought, some California water users are far more equal than others.
   
An Associated Press review finds nearly 4,000 California companies, farms and others are allowed to use free water with little oversight even as deliveries to nearly everyone else have been severely slashed.
   
Their special status dates back to claims made more than a century ago when water was plentiful. These "senior rights holders" dominated by corporations and agricultural concerns are not obliged to conserve water.
   
Together, they hold more than half the rights to rivers and streams in California.
   
The AP found the state's monitoring system is based on self-reported, error-filled records. The state only collects the records every three years on a staggered basis, meaning its information is always out of date.
   
The antiquated system blunts California's ability to move water where it is most needed.