The Basic Standards and Methodologies for Surface Waters (Regulation No. 31, 5 CCR 1002-31) contains antidegradation provisions which provide three separate levels of antidegradation protection (see section 31.8). This document is intended to provide guidance to Water Quality Control Division staff and to the public regarding the implementation of the antidegradation significance tests found in Regulation No. 31. This guidance is designed as a framework to provide a documented methodology and to ensure antidegradation reviews are conducted in a consistent manner. Unique situations will be assessed on a case-by-case basis, using site-specific data and methodology.
