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 States Water Quality Standards help ensure that all Iowans have surface waters that are fishable and swimmable to the fullest extent practicable, safe drinking water, groundwater that is free from harmful contamination, protection from the adverse effects of floods, and water resources that are put to their best beneficial uses.

Copper Criteria Update

The DNR is updating the copper criteria for aquatic life protection. The purpose of the proposed rule is to create additional flexibility for wastewater dischargers by adding the option to use the Biotic Ligand Model (BLM) to determine copper water quality criteria or to use the Water-Effect Ratio (WER) to adjust the existing copper water quality criteria.  Following are the documents associated with this proposal:

Implementation Procedure for Copper BLM
Responsiveness Summary
Notice of Intended Action
Fiscal Impact Statement for Copper Criteria Update
Jobs Impact Statement for Copper Criteria Update
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

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.

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:
Matthew Dvorak

Iowa’s chemical criteria includes both numerical criteria listed in 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


DNR Contact:
Connie Dou

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.

Linked below are documents relating to the current Triennial Review for Iowa's water quality standards.

2015-2017 Triennial Review Documents:

DNR Contact:
Matthew Dvorak