Cal. Water Code § 10722.4

(a) Pursuant to Section 10933, for the purposes of this part the department shall categorize each basin as one of the following priorities:
1. (1) High priority.
2. (2) Medium priority.
3. (3) Low priority.
4. (4) Very low priority.
(b) The initial priority for each basin shall be established by the department pursuant to Section 10933 no later than January 31, 2015.
(c) Any time the department updates Bulletin 118 boundaries pursuant to subdivision (b) of Section 12924, the department shall reassess the prioritization pursuant to Section 10933.
(d) If the department changes priorities pursuant to Section 10933 to elevate a basin from a low- or very low priority basin to a medium- or high-priority basin after January 31, 2015, the agency formation and planning deadlines of this part shall be extended as follows:
1. (1) A local agency, or combination of local agencies overlying a groundwater basin, shall have two years from the date of reprioritization to either establish a groundwater sustainability agency pursuant to Chapter 4 (commencing with Section 10723) or two years to satisfy the requirements of Section 10733.6.
2. (2) A groundwater sustainability agency shall have five years from the date of reprioritization to meet the requirements of subdivision (a) of Section 10720.7, except that if the reprioritization occurs before January 31, 2017, a groundwater sustainability agency subject to paragraph (2) of subdivision (a) of Section 10720.7 shall have until January 31, 2022.