Inland shrimp farms have also been tried in some regions, but the need to ship salt water and competition for land with agricultural users led to problems.
A senior federal official involved with assessing the proposed exemptions said that most of the agricultural users had legitimate reasons.
In particular, cutting back agricultural users by this administration will be remembered as quite an extraordinary thing.
Competition for water could increase on the plains, where agricultural and industrial users compete for available water.
Diesel had by this point long been a popular choice for taxi operators and agricultural users.
In December, the state notified agricultural users to expect only 35 percent of their requests.
The California Farm Water Coalition, which represents agricultural users, said that the direct loss to farmers alone could exceed $1 billion.
For example, it has been observed that urban users can pay up to 10 times more for water than agricultural users.
Purified water is currently supplied to the region's major power stations, and in future will also be supplied to other industrial and agricultural users.
The right of agricultural users to the water were provisional until irrigation actually began producing crops as provided by the Carey Act.