California Code, Public Utilities Code - PUC § 13573

No person shall discharge waste water into a community sewer system connected to or directly into a district interceptor which will result in contamination, pollution or a nuisance. All discharges of waste water which are, or could be, harmful to or unreasonably affect the sewage disposal facilities of a district, or which impair or unreasonably affect the operation and maintenance of such facilities, or which violate quantity, quality and flow standards adopted by the district, and all waste water discharges which unreasonably affect, or could unreasonably affect, the quality of the district's treatment plant effluent in such a manner that receiving water quality requirements established by law cannot be met by the district, shall constitute a nuisance for the purposes of this article.