When an industrial point source discharger continuously monitors the pH of wastewater in accordance with the requirements of a WPDES permit and the pH limits in the permit are established as part of the effluent limitations applicable to the category of dischargers to which the industrial point source belongs, the permittee shall maintain the pH of such wastewater within the range of the categorical limits, except pH excursions from the range are permitted subject to the following constraints:
Wis. Admin. Code Department of Natural Resources NR 205.06