The order adds Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, San Francisco, and Ventura counties.
The proclamation authorizes state water boards to ban wasteful water use.
Newsom is urging Californians to redouble water conservation efforts. His action today comes as the state reports urban water use was reduced by 5% in August.
In July, he issued an order for California to voluntarily reduce water use by 15%.
“As the western U.S. faces a potential third year of drought, it’s critical that Californians across the state redouble our efforts to save water in every way possible,” said Governor Newsom.