2010 305(b) Assessment Summary
Legacy Assessment Summary
Beginning with the 2016 assessment cycle, the format of assessments was changed from assessing the overall status of a waterbody segment to a more detailed assessment of individual use attainment for each segment. This change implemented US EPA's guidelines for assessments and required a change in database structure to support the new assessment methodology. These pre-2016 assessments are referred to as "Legacy Assessments" and their format is preserved, as that was the official submission for those Integrated Reports. Assessments for the 2016 and later use the current EPA guidelines.
Due to this change in assessment format, summary information for legacy assessment cycles is limited.
The draft IR methodology and assessments are released for public review. The public has 30 days to comment on the IR methodology, data, or the assessments during this period.
The Iowa draft Integrated Report is submitted to US EPA Region 7 for review and approval.
The Integrated Report has been approved and finalized.
Documentation
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.
The final methodology used for this assessment cycle can be downloaded from the State Library of Iowa - Iowa Publications Online website.
For a 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. This cycle's assessment unit designated uses are based on this version of the Surface Water Classification document.
Designated Uses and Assessment Categories
Each assessment unit has one or more Designated Uses. Beneficial uses designated for Iowa's surface waters are protected by narrative and numeric water quality criteria. A waterbody may be supporting one or more uses, but if a single parameter or analyte that fails to meet the criteria for a use (such as low dissolved oxygen or a low fish biotic index score) can result in that waterbody being placed on the Impaired Waters List. The U.S. EPA guidelines suggest that states place all their waters into one of the following categories that comprise a state's Integrated Report.
Supported Waters
Supported 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.
Waters In Need of Further Investigation (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. 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
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.
Not Assessed
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.
Assessment Results
Overall Integrated Report Categories
| Category - Description | Waterbody Segments |
|---|---|
| 1 -- All designated uses are met. | 9 |
| 2 -- Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met. | 349 |
3 -- Insufficient data exist to determine whether any designated uses are met.
EPA Category 3 and WINOFIsIowa 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 250 WINOFI segments and 1024 "Not Assessed" segments. |
1274 |
| 4 -- Water is impaired or threatened and a TMDL has been completed or is not needed. | 132 |
| 5 -- Water is impaired or threatened and a TMDL is needed. | 474 |