Water Quality Standards

Water quality standards are the foundation of the water quality-based control program mandated by the federal Clean Water Act. Water Quality Standards define the goals for a waterbody by designating its uses, setting criteria to protect those uses, and establishing provisions to protect water quality from pollutants. A water quality standard consists of three basic elements:

1. Designated uses of the water (e.g., fish and aquatic life, recreation, fish consumption),
2. Water quality criteria to protect designated uses (numeric pollutant concentrations and narrative requirements), and
3. An antidegradation policy to maintain and protect existing uses and high quality waters.

Water quality standards for surface waters are described in Chapters NR 102, 104, and 105 of the Wisconsin Administrative Code. These rules include general policies and detailed provisions describing implementation issues such as mixing zone provisions, variances, etc.

Water Quality Standards are important because they help water quality managers to protect and restore the quality of the Nation´s surface waters, consistent with the requirements of the Clean Water Act. Specifically, standards help to identify water quality problems in streams, rivers, or lakes that may have been caused by human activities like improperly treated wastewater discharges, runoff or discharges from active or abandoned mining sites, excessive sedimentation from runoff of soil, over-application of fertilizers and chemicals from agricultural areas, or erosion of stream banks caused by improper grazing practices. Standards also support efforts to achieve and maintain protective water quality conditions, including:

1. Total maximum daily loads (TMDLs), waste load allocations (WLAs) for point sources of pollution, and load allocations (LAs) for non point sources of pollution,
2. Water quality management plans which prescribe the regulatory, construction, and management activities necessary to meet the water body goals,
3. NPDES water quality-based effluent limitations for point source discharges,
4. Water quality certifications under CWA § 401 for activities that may affect water quality and that require a federal license or permit, and
5. Reports, such as the reports required under CWA § 305(b), that document current water quality conditions.
6. CWA § 319 management plans for the control of non point sources of pollution.