Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

2020 Assessment Summary - Category 5 - Water is impaired or threatened and a TMDL is needed

303(d) List of Impaired Waters

The State's Section 303(d) list of impaired waters. The waterbody is impaired and a total maximum daily load (TMDL) is needed.
View Map of Impaired Segments
TMDL Priorities

Iowa DNR prioritizes TMDLs that are able to address impairments on waterbodies with a high potential for social impact. The TMDL priority does not necessarily indicate the severity or significance of the impairment

Tier I
impairments with a realtively high social impact and relatively low complexity and/or cost for TMDL development
Tier II
impairments with a realtively high social impact and relatively high complexity and/or cost for TMDL development
Tier III
impairments with a realtively low social impact and relatively low complexity and/or cost for TMDL development
Tier IV
impairments with a realtively low social impact and relatively high complexity and/or cost for TMDL development
Note: Mouse over (or click on a mobile device) the icon for descriptions of those field values. Additional information can be found in the reference codex.
PS
Partially Supported
NS
Not Supported
A1
Recreation: Primary contact
A2
Recreation: Secondary contact
A3
Recreation: Children's contact
BCW1
Aquatic Life: Cold Water Type 1
BCW2
Aquatic Life: Cold Water Type 2
BLW
Aquatic Life: Lakes and wetlands
BWW1
Aquatic Life: Warm Water Type 1
BWW2
Aquatic Life: Warm Water Type 2
BWW3
Aquatic Life: Warm Water Type 3
C
Drinking Water
HH
Human Health
OIW
Outstanding Iowa Water
5*
303(d)-impaired last cycle; fully supporting this cycle; potential de-listing.
5a
Pollutant-caused impairment. TMDL needed.
5b
Biological impairment or pollutant-caused fish kill - unknown source. No administrative action.
5b-t
Biological - tentative
5b-v
Biological - verified
5p
Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.
Waterbody ADB Code Type Use Support Code Cause of Impairment Listing Info