A. The city determines that the limitations may not be sufficient to protect the operation of community sewers and the POTW.

B. The city determines that the limitations may not be sufficient to enable the POTW to comply with water quality standards, or effluent limitations specified in the POTW’s NPDES permit, or the POTW’s general water reuse permit.

C. The discharge is of such a nature that it alone or in combination with other discharges reduces or threatens to impair the POTW effluent, reuse, discharge, or sludge disposal options.

D. In the city’s evaluation, the discharge, alone or in combination with any other discharge, poses a threat or unreasonable risk to the POTW or personnel.

The city may also, through the use of the permit, make specific allocations of pollutants to industries. These allocations or local limits shall be across-the-board local limits (or "uniform concentration limits"), local limits by industrial contributory flow and industry-specific local limits by mass proportion.

These allocation methods shall not allow any increased loading of any pollutant to the POTW nor shall they allow higher limits than federal categorical standards. These allocations or local limits shall be evaluated and adjusted from time to time to ensure that the loading of any pollutant to the POTW on a system-wide basis is sufficiently low to ensure that the POTW can comply with existing and future regulatory requirements.