Water Quality Standards

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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 States Water Quality Standards help ensure that all Iowans have surface waters that are fishable and swimmable to the fullest extent practicable and water resources that are put to their best beneficial uses.

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 Procedure for Copper BLM.

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

Copper Criteria

Waterbody	Upstream latitude (degrees)	Upstream longitude (degrees)	Downstream latitude (degrees)	Downstream longitude (degrees)	Acute copper criterion (µg/L)	Chronic copper criterion (µg/L)
Floyd River	43.1824	-95.8676	43.0684	-95.9153	55.8	33.4

Chapter 61 Rule Making: Aquatic Life Water Quality Criteria for Metals

The Environmental Protection Commission (EPC) has amended Chapter 61 to update aquatic life water quality criteria for selected metals. The final rule will be effective November 11, 2020. Public comments were addressed in a public participation responsiveness summary.

View the Chapter 61 Amendments

View the Public Participation Responsiveness Summary

Questions regarding the new water quality criteria can be directed to Katie Greenstein at 515-490-2095 or katie.greenstein@dnr.iowa.gov.

+ 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 web page.

+ Chemical Criteria

61.3(3) Table 1 and General Water Quality Criteria described in 61.3(2). Numerical criteria apply to designated waters and general water quality criteria are applicable to all surface waters including general use and designated use waters. The following documents share information about specific criteria.

Chloride and Sulfate Criteria

Iron

Copper Criteria Documents Implementation Procedure for Copper 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

DNR Contact: Katherine Greenstein katie.greenstein@dnr.iowa.gov

+ 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. See Chapter 61: Water Quality Standards. This review includes, but is not necessarily limited to: designated uses, criteria, and antidegradation.

DNR Contact: Roger Bruner, 515-310-0247, roger.bruner@dnr.iowa.gov

+ Use Assessments and Use Attainality Analysis

Under Iowa's Water Quality Standards, it is presumed that all perennial streams and rivers are attaining the highest level of recreation and aquatic life uses and should be protected for activities such as fishing and swimming. A use assessment and use attainability analysis (ua/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 assign a more appropriate recreational and aquatic life use classification.

Assessing Iowa Stream Uses Fact Sheet - fact sheet explaining ua/uaas and designated uses

Surface Water Classification Document - rule referenced document containing a list of designated stream in Iowa and their use classifications.

Use Assessment/use Attainability Analysis Search - this database provides the opportunity to view the department's recommended use designations and supporting information.

Assessment Protocols: warm water stream use designation protocol cold water protocol recreational use assessment and attainability analysis protocol

Help us assess Iowa's streams: take the survey. The DNR is asking for your input on how you recreate in Iowa's streams as we complete recreational assessments on streams in the state. Please take our online survey to list the streams you use, what activities you use them for and where you access the streams. The DNR will factor the results from the survey into its decision making for applying recreation-based stream designations to Iowa's waters. These assessments are part of classifying recreational stream uses in the state, and will help determine the appropriate level of protection for the stream.

US Environmental Protection Agency's Action Letter for Batch 4 - document containing EPA's review of batch 4 UAA's.

DNR Contact: Roger Bruner, 515-310-0247, roger.bruner@dnr.iowa.gov