Water Quality Standards

The DNR manages water quality through the implementation of the State's water quality standards. These standards are found in Chapter 61 of the Iowa Administrative Code. The State's water quality standards help ensure that all Iowans have surface waters that are fishable and swimmable and water resources that are put to their best beneficial uses.

Antidegradation

Antidegradation refers to federal regulations designed to maintain and protect high quality waters and existing water quality in other waters from unnecessary pollution. For further information please visit the Antidegradation webpage.

Water Quality Criteria

General water quality criteria are described in 61.3(2) and are applicable to all surface waters, including general use and designated use waters. Tables in 61.3(3) lists numeric criteria, which apply to all designated use waters. The following documents share information about specific criteria.

• Revising Criteria for Chloride, Sulfate and Total Dissolved Solids
• Iron Criteria and Implementation For Iowa Surface Waters

Copper Criteria Documents

• Implementation Procedures for the Site-Specific Application  of Copper Biotic Ligand Model (BLM) 
• Aquatic life ambient freshwater quality criteria - Copper 2007 Revision (epa-822-r-07-001), February 2007
• Streamlined Water-effect Ratio Procedure for Discharges of Copper (epa-822-r-01-005), March 2001
• Interim Guidance on Determination and Use of Water-effect Ratios for Metals (epa-823-b-94-001), February 22, 1994

Site-Specific Water Quality Criteria

Clean Water Act rules allow for site-specific water quality criteria approved by the EPA. Site-specific water quality criteria are established when localized water quality parameters are used to derive criteria in accordance with Iowa’s water quality standards (567 Iowa Administrative Code Chapter 61). For example, the copper biotic ligand model (BLM) may be used to establish site-specific copper criteria as described in the rule-referenced Implementation Procedures for the Site-Specific Application  of Copper Biotic Ligand Model (BLM) .

Site-specific water quality criteria implemented in Iowa are shown in the table below.

Copper Criteria

Triennial Review

Under the Clean Water Act, a state shall, from time-to-time, hold public meetings for the purpose of reviewing applicable water quality standards and, as appropriate, modifying and adopting standards. This review includes, but is not necessarily limited to: designated uses, water quality criteria, and antidegradation.

Use Attainability Analysis (UAA)

Under Iowa's water quality standards, it is presumed that all perennial streams and rivers on the 1:100,000 DLG hydrography data map (published July 1993) and intermittent streams with perennial pools not already designated in the Surface Water Classification Document are attaining the highest level of recreational (A1) and aquatic life (BWW1) uses and should be protected for activities such as fishing and swimming.  A use attainability analysis (UAA) is a process of gathering field data and assessing the available information to determine if a stream is capable of supporting the highest level of recreation and aquatic life uses, and, if not, assigning more accurate recreational and aquatic life uses.

Assessment Protocols:

• Warm Water Stream Use Assessment and Attainability Analysis Protocol 
• Cold Water Use Designation Assessment Protocol
• Recreational Use Assessment and Attainability Analysis Protocol 

Surface Water Classification document - A rule referenced document containing a list of designated water bodies in Iowa and their designated uses.

Use Attainability Analysis Database - The UAA database contains all the information on UAAs up to 2022. Any UAAs after 2022 that are put out on public notice will be posted to the water quality standards  webpage under a UAA public notices heading. Once the UAAS are adopted into rule, they will be posted to ADBNet.

Water Quality Standards: Surface Water Classifications Fact Sheet - A fact sheet describing how water bodies are classified in Iowa.

Water Quality Standards: Use Attainability Analysis (UAA) Fact Sheet - A fact sheet explaining UAAs in Iowa.