2018 305(b) Assessment Summary
2018 Integrated Report including the 2018 Impaired Waters List: Approved by U.S. EPA March 24, 2020:
Iowa DNR submitted the 2018 Integrated Report which includes the 2018 Impaired Waters List to the U.S. EPA as required by Sections 305(b) and 303(d) of the federal Clean Water Act for approval on February, 24 2020. Iowa DNR received final approval of this submittal from the U.S. EPA on March 24, 2020.
Public comments were sought on Iowa’s draft 2018 list of impaired waters from November 14, 2019 through December 28, 2019. Iowa DNR prepared a summary of responses to the 102 comments received on the draft 2018 list of Impaired Waters Iowa’s draft list was updated following the public comment period and Iowa's final 2018 Impaired Waters list, as submitted to U.S. EPA, contained 622 waterbodies with a total of 831 impairments.
Materials for review
- 2018 Iowa Integrated Report EPA Submittal Letter
- Methodology for Iowa’s 2018 Water Quality Assessment, Listing, and Reporting Pursuant to Sections 305(b) and 303(d) of the Federal Clean Water Act.
- Public Participation Responsiveness Summary for Iowa's 2018 Section 303 (d) list of Impaired Waters
- 2018 303(d) Impaired Waters List USEPA Region 7 2018 Approval Letter
- 2018 303(d) Impaired Waters List USEPA Region 7 2018 Decision Document
Links to additional background information can be found at:
Iowa's Section 303(d) lists and Integrated Reports are prepared according to Iowa DNR's assessment and listing methodology and follow U.S. EPA guidelines for "integrated reporting" that combine requirements of Sections 305(b), 303(d), and 314 of the federal Clean Water Act. These U.S. EPA guidelines suggest that states place all their waters into one of the following categories that comprise a state's Integrated Report:
- Supporting: These waterbody segments are assessed as fully supporting their assessed designated uses*. Segments assessed as supporting all their designated uses are in Category 1 of the Integrated Report. Those segments where some of the designated uses are met but insufficient information exists to determine whether the remaining uses are met are placed in Category 2 of the Integrated Report.
- Uses Not Assessed: These are designated uses for which insufficient information exists to determine whether that designated use is met. Other designated uses for that waterbody, however, may have been assessed as either "supporting" or "impaired".
Waterbody segments Not Assessed: Insufficient information exists to determine whether any beneficial uses designated for that segment are met. These segments are placed into Category 3 of the Integrated Report.
Category 4: The waterbody segment is impaired but a TMDL is not required; the waterbody segment is not included on the state's section 303(d) list of impaired waters(Category 5 of the Integrated Report).
Category 5: The states Section 303(d) list of impaired waters. The waterbody segment is impaired and a total maximum daily load (TMDL) is needed. The list contains 622 waterbodies with a total of 831 impairments. There were 608 segments with 818 impairments on Iowa's 2016 final EPA-approved list.
WINOFI: As provided for in Iowa's credible data law, the Department is to maintain a separate list of waters that require further investigative monitoring before a “monitored” assessment can be prepared. As specified in thecredible data law,this list is not part of the Section 303(d)/impaired water segments process in Iowa and includes waterbody segments where limited information suggests, but does not conclusively (credibly) demonstrate, a water quality impairment. If the results of further investigative monitoring demonstrate, with data of sufficient quality and quantity, that a water quality impairment exists, the affected waterbody can be added to Iowa's Section 303(d) list. Iowa's draft 2018 list of waters in need of further investigation contains 472 waterbody segments.
Delistings: These water segments are proposed for removal from Iowa's previous (2016) list of impaired waters. A rationale for each proposed delisting is provided.
[*Designated uses are beneficial uses applied to specific Iowa surface waters (streams, rivers, lakes, and wetlands) in the Iowa Water Quality Standards. Examples of beneficial uses are uses for primary contact recreation (for example, swimming-type uses), aquatic life protection, and as a source of water for a public water supply. Beneficial uses designated for Iowa's surface waters are protected by narrative and numeric water quality criteria. For a more detailed description of designated uses applied to Iowa surface waters, see pages 9 and 10 [Surface Water Quality Criteria, Designated Use Segments] of the Iowa Water Quality Standards. For a list of the Iowa surface waters and their respective designated uses, see Iowa's Surface Water Classification.]
Healthy waters are those segments in Integrated Report Categories 1 and 2.
- Category 1: All designated uses are met
- Category 2: One or more designated uses are met, but there are insufficient data to determine if the remaining designated uses are met.
As provided for in Iowa's Credible Data Law, the Department is to maintain a separate list of waters that require further investigative monitoring. This list is not part of the Section 303(d)/impaired waters process in Iowa and includes segments where limited information suggests, but does not conclusively (credibly) demonstrate, a water quality impairment. If the results of further investigative monitoring demonstrate, with data of sufficient quality and quantity, that a water quality impairment exists, the affected segment can be added to Iowa's Section 303(d) list.
Impaired waters are those segments in Integrated Report Categories 4 and 5.
- Category 4: The segment is impaired but a TMDL is not required; the segment is not included on the state's section 303(d) list of impaired waters (Category 5 of the Integrated Report).
- Category 5: Iowa's Section 303(d) List of Impaired Waters. The segment is impaired and a total maximum daily load (TMDL) is needed.
The number of assessments the Iowa DNR can make in a given cycle are limited by budgets and staffing resources.
- Category 3: Insufficient data to determine whether any designated uses are met.
Rivers and Streams
Lakes and Reservoirs
Category 5 Impaired Waters List
Overall Integrated Report Categories
|Category - Description||Waterbody Segments|
|1 - All designated uses are met.||11|
|2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.||352|
3 - Insufficient data exist to determine whether any designated uses are met.
EPA Category 3 and WINOFIs
Iowa maintains a separate list, per the Credible Data Law, of segments with insufficient information (WINOFI). Because these segments do not have enough information to determine use support, EPA considers these "Not Assessed". Therefore, for the purpose of reporting the Integrated Report to EPA, these WINOFI segments are grouped into the EPA's Category 3.
For this cycle, there are a total of 292 WINOFI segments and 1138 "Not Assessed" segments.
|4 - Water is impaired or threatened and a TMDL has been completed or is not needed.||145|
|5 - Water is impaired or threatened and a TMDL is needed.||622|
Designated Use Assessment Summaries
While the health of a waterbody as a whole is an important consideration, it's also important to view how the individual uses of the segment are being supported. The treemaps below are split out by designated use. Within each use are relatively-sized containers that display each waterbody type and the support level attained by those uses. Mouse-over each box for a popup containing full details of the node.