(b) Facility expansion, as defined in section 750-1.2 of this Part, for all existing SPDES permittees that are not POTWs must be reported by submission of a letter to the regional water engineer. The department may determine that additional information must be submitted or that the information submitted by letter to the regional permit administrator must be submitted on a department application form. The department may determine, on the basis of such information, and any related investigation, inspection or sampling, that a modification of the permit is necessary to assure maintenance of water quality standards or compliance with other provisions of ECL, article 17 or the Clean Water Act. Conversely, the department may determine in accordance with this Part that the proposed activity does not require a permit modification. Unless the department determines that a permit modification is unnecessary, operations that fit the following criteria, which may result in discharges that are not discharges authorized by the SPDES permit, are prohibited until the permit has been modified in accordance with Part 621 of this Title:

1. (1) increases in production or the mass of any one pollutant in wastewater that occur and are expected to continue or have occurred and been existing for more than one year; or
2. (2) the permittee commences a new operation, of which no operations in this category currently exist at the facility, subject to regulation under 40 CFR 405 to 471 and/or 40 CFR part 125 (see section 750-1.25 of this Part) which will result in pollutants which the permittee knows or has reason to believe will be discharged (except substances not required to be reported on the appropriate and current New York State SPDES permit application) and which is not described in the SPDES permit application record upon which the current permit is based.