2010 California Code
Water Code
Chapter 4. Modification Of Decrees

2900.  In rendering its decree for the determination of rights to
water, whether in suits referred to the board under the provisions of
Chapter 1 of this part or in adjudications under the provisions of
Chapter 3 of this part, the court may provide that the board or any
party affected by the decree may, at any time within three years from
entry thereof, apply to the court for a modification of the decree
insofar only as the decree determines quantities of water, and after
hearing the motion and any competent and admissible evidence offered
in support of or against the motion the court may modify the decree
by increasing or decreasing the quantities of water therein allowed.