Federal regulations require the Water Department  to issue industrial wastewater discharge permits to all industries classified as significant industrial users.  The following criteria, defined in the EPA's General Pretreatment Regulations (40 CFR 403), are used to determine if an industry is a significant industrial user:

1. Conduct operations that are subject to the EPA's categorical pretreatment standards, or
2. Discharge an average of 25,000 gallons per day or more of process wastewater, or
3. Contribute a process waste-stream which makes up 5 percent or more of the average dry weather hydraulic or organic capacity of a District sewage treatment plant, or
4. Have a reasonable potential for adversely affecting the District's operations or for violating any pretreatment standard or requirement.

Permits follow a standard format designed to provide permittees with complete information as to their discharge limitations, sampling and reporting obligations, general conditions and special conditions.  Complete information on the user, including sampling point locations, applicable pollutants to be monitored, discharge standards to be met, reporting requirements and other useful information are all maintained to help develop the permit.  This information is constantly being updated as new information is received such as following a facility inspection.

All permittees are required to submit quarterly self-monitoring reports for the life of the permit, typically five years.  These reports are to include the results of all sampling conducted during the quarter and to also include applicable general and special certification statements.  Most permittees are required to sample each permitted discharge point quarterly, but in the case of very small operations, infrequent batch discharge or sanitary only situations, less frequent sampling may be allowed.  The quarterly report is still required in these cases but for the quarters in which sampling does not occur, the permittee is only required to provide the applicable certifications.  An example of a typical certification requirement is metal finishers and no dumping of toxic organics.  Another is no-discharge certification of categorical wastes for cases where the regulations set no-discharge as the standard.  For a case whereless-than-quarterly sampling is allowed, there is a required certification stating there has been no change in the character of the discharge since the last report.