CA SB1262

Requires cities and counties to identify water systems whose service area includes or is adjacent to project sites when determining California Environmental Quality Act compliance, and specifies that hauled water cannot be counted as a water source.

Expands water supply assessments for projects relying on groundwater to include information about basin adjudication status, groundwater sustainability plans, overdraft conditions, and historical groundwater pumping data.

Revises the definition of "sufficient water supply" for residential subdivisions to require consideration of a 20-year projection period under normal and drought conditions, plus additional groundwater-specific factors including sustainability plans and extraction rights.

Requires public water systems to verify water supply availability within 90 days of request from local agencies, with provisions for mandamus writs if verification is not provided and allows local agencies to override negative determinations with substantial evidence.

Exempts the state from reimbursing local agencies for implementation costs under Article XIII B of the California Constitution because local agencies may levy service charges or fees sufficient to pay for these requirements.