The governing body of any local agency shall determine whether the discharge of waste from the proposed subdivision into an existing community sewer system would result in violation of existing requirements prescribed by a California regional water quality control board pursuant to Division 7 (commencing with Section 13000) of the Water Code. In the event that the governing body finds that the proposed waste discharge would result in or add to violation of requirements of such board, it may disapprove the tentative map or maps of the subdivision.
Source:
Section 66474.6, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=66474.6..