Water Quality Standards and Classifications

Water quality standards are important because they help water quality managers protect and restore the quality of Wisconsin's waters.

Our water quality may be impacted by many different sources and types of pollution. Under the Clean Water Act, every state must adopt water quality standards to protect, maintain and improve the quality of our nation’s surface waters. These standards set the appropriate level of protection by:

• determining the types of activities the water should support by establishing designated uses;
• developing water quality criteria to protect these uses from excess pollution;
• establishing an antidegradation policy to maintain and protect existing uses and high-quality waters; and
• identifying general policies to implement these protection levels in point source discharge permits.

Water quality standards also support efforts to achieve and maintain protective water quality conditions, including:

• the development of reports that document current water quality conditions;
• the establishment of permit limits for wastewater discharges to protect the state's waters;
• the development of total maximum daily load (TMDL) analyses which determine how much pollutant reduction is needed in a watershed to protect water quality; and
• the development of water quality management plans which prescribe the regulatory, construction and management activities necessary to meet the water body goals.

Public participation

Any interested individual can have a role in the process of developing water quality standards. The DNR reviews and, as appropriate, revises water quality standards at least once every three years. To find out more about this process and how you can be involved, visit triennial standards review.

When revisions to water quality standards are proposed, the public is notified of these revisions and a public hearing is held to gather input and comments. Several water quality standards rules are currently under revision or development. For a brief description of these revisions, visit water quality standards updates.

Areas of Special Natural Resources Interest (ASNRI)

The state also classifies waterbodies using several categories that indicate special ecological value, which collectively are known as Areas of Special Natural Resources Interest (ASNRI).  While ASNRI classifications are not explicitly water quality standards like designated use classifications, they are an important basis for many types of management decisions.

ASNRI-designated areas include the following:

• State natural areas designated or dedicated under Subsection 23.27 to 23.29, Wis. Stats. [PDF exit DNR].
• Trout streams as designated by the department under Chapter NR 1.02(7), Wis. Adm. Code [PDF exit DNR].
• Outstanding or exceptional resource waters under Section 281.15, Wis. Stats. [PDF exit DNR].
• Wild rice waters as identified by the department and the Great Lakes Indian Fish and Wildlife Commission [exit DNR].
• Waters in areas identified in a special area management plan (SAMP) or special wetland inventory study (SWIS) under Chapter NR 103.04, Wis. Adm. Code [PDF exit DNR].
  • Note: Special area management plans exist for the City of Superior (Douglas County) and Chiwaukee Prairie (Kenosha County). A Special Wetland Inventory Study exists for the area bordering the bay of Green Bay. In the Surface Water Data Viewer, these three datasets are combined together as Quality Wetlands.
• Waters in ecologically significant coastal wetlands along Lakes Michigan and Superior as identified in the Coastal Wetlands of Wisconsin (DNR–CMP project).
• Federal or state waters designated as wild or scenic rivers under Sections 30.26 and 30.27, Wis. Stats. [PDF exit DNR].
• The portion of a body of water that contains a sensitive area under Section 30.01(6b), Wis. Stats. [PDF exit DNR].