The amendment to the Water Act, which was approved by this House this summer, does not mean anything other than the duty of water
managers to monitor the amount of this polluted water from the lavatories, wash basins, but also from industrial plants that flow directly into our rivers.
The Attorney General stated that "even with rights which authorized a three acre foot duty that had never been used, users wishing to change cropping patterns would be entitled to use a three acre foot duty, if their system had been capable of diverting the full amount had it been necessary."(130) To become a perfected right, a water user must apply all of the water to a beneficial purpose.(131) In the Attorney General's example, the three acre foot duty of water had never been applied to a beneficial use and is technically not part of the right in the first place.
Under early case law, the duty of water awarded upon application for the appropriation depends on the following three factors: 1) the amount diverted, 2) the amount used, and 3) the amount needed.(141) These three factors are combined to define the beneficial use.(142) After the right is perfected, the quantity of water appropriated is limited to the lowest of the three factors.(143) Therefore, the beneficial use is an expression of the lowest factor.(144)
Most often, the lowest factor has been the amount needed to accomplish the beneficial use.(145) Therefore, the duty of water is really a maximum estimated number that expresses "the amount of water necessary to produce a desired benefit."(146) For irrigation, WRD calculates the duty of water based on "the character of the soil, the manner of application, and the climate, as well as other factors."(147) If the user installs a more efficient irrigation system, the amount needed to achieve the beneficial use decreases and the conserved water is forfeited to the state to be used by someone else.(148)