10609.20.
(a) Each urban retail water supplier shall calculate its urban water use objective no later than January 1, 2024, and by January 1 every year thereafter.(b) The calculation shall be based on the urban retail water supplier’s water use conditions for the previous calendar or fiscal year.
(c) Each urban water supplier’s urban water use objective shall be composed of the sum of the following:
(1) Aggregate estimated efficient indoor residential water use.
(2) Aggregate estimated efficient outdoor residential water use.
(3) Aggregate estimated efficient outdoor irrigation of landscape areas with dedicated irrigation meters or equivalent technology in connection with CII water use.
(4) Aggregate estimated efficient water losses.
(5) Aggregate estimated water use in accordance with variances, as appropriate.
(d) (1) An urban retail water supplier that delivers water from a groundwater basin, reservoir, or other source that is augmented by potable reuse water may adjust its urban water use objective by a bonus incentive calculated pursuant to this subdivision.
(2) The water use objective bonus incentive shall be the volume of its potable reuse delivered to residential water users and to landscape areas with dedicated irrigation meters in connection with CII water use, on an acre-foot basis.
(3) The bonus incentive pursuant to paragraph (1) shall be limited in accordance with one of the following:
(A) The bonus incentive shall not exceed 15 percent of the urban water supplier’s water use objective for any potable reuse water produced at an existing facility.
(B) The bonus incentive shall not exceed 10 percent of the urban water supplier’s water use objective for any potable reuse water produced at any facility that is not an existing facility.
(4) For purposes of this subdivision, “existing facility” means a facility that meets all of the following:
(A) The facility has a certified environmental impact report, mitigated negative declaration, or negative declaration on or before January 1, 2019.
(B) The facility begins producing and delivering potable reuse water on or before January 1, 2022.
(C) The facility uses microfiltration and reverse osmosis technologies to produce the potable reuse water.
(e) (1) The calculation of the urban water use objective shall be made using landscape area and other data provided by the department and pursuant to the standards, guidelines, and methodologies adopted by the board. The department shall provide data to the urban water supplier at a level of detail sufficient to allow the urban water supplier to verify its accuracy at the parcel level.
(2) Notwithstanding paragraph (1), an urban retail water supplier may use alternative data in calculating the urban water use objective if the supplier demonstrates to the department that the alternative data are equivalent, or superior, in quality and accuracy to the data provided by the department. The department may provide technical assistance to an urban retail water supplier in evaluating whether the alternative data are appropriate for use in calculating the supplier’s urban water use objective.
(f) (1) The department shall update methodologies and criteria for calculating residential and CII landscape areas, if necessary to accomplish the purposes of this chapter, and determine landscape area measurements within each urban retail water supplier’s service area to be completed by January 1, 2028, and once every five years thereafter.
(2) Landscape area measurements determined pursuant to paragraph (1) shall, no later than January 1, 2039, include tree canopy coverage data for purposes of calculating a variance for water use associated with irrigating existing trees in residential landscapes and CII landscape areas with dedicated irrigation meters.
(3) The department shall post landscape area measurement data on its internet website.