Iowa DNR
ADBNet

Water Quality Assessments

Impaired Waters List

Hewitt Creek IA 01-NMQ-109

mouth (S29/30 T89N R2W Dubuque Co.) to confluence with Hickory Cr. in S21 T89N R2W Dubuque Co.

Assessment Cycle
2024
Release Status
Pending
Data Collection Period
Overall IR Category
3 - Insufficient data exist to determine whether any designated uses are met.
Trend
Unknown
Created
11/1/2023 8:13:58 AM
Updated
1/24/2024 9:01:00 AM
Assessment conducted in accordance with Iowa's 2024 IR methodology.
Use Support
Class A1
Not Assessed
Class BWW2
WINOFI
Fish Kill: Caused By Animal Waste
Support Level
Water in Need of Further Investigation (WINOFI)
Impairment Code
3b - Use potentially impaired based on an evaluated assessment.
Cause Magnitude
High
Status
Continuing
Source
Agriculture: Feedlots
Source Confidence
N/A
Cycle Added
2020
Impairment Rationale
Pollutant-caused fish kill
Data Source
Fish kill investigation: Iowa DNR
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class BWW2 use was assessed as “WINOFI” based on a fish kill investigation. All other designated uses were "not assessed."

Assessment Explanation

Presumptive Class A1 - No Data

Class BWW2 - Fish kill Assessment:

The Class BWW2 aquatic life use assessment based on the 2017 fish kill initially placed this segment in Category 4d. The fish kill was caused by a “pollutant” or was suspected to be caused by a “pollutant”; therefore, the Class BWW2 use was considered impaired. However, because restitution for the fish killed was received, the Class BWW2 use was placed in Category 4d (impaired but TMDL not required). DNR feels that (1) TMDLs should not be required for a fish kill caused by a one-time illegal or unauthorized release of a pollutant where enforcement action was taken and (2) enforcement action is more appropriate and effective for addressing a spill-related impairment than the TMDL process. Based in DNR IR methodology, the fish kill is now greater than five years old (2022); therefore, this BWW2 fish kill assessment was moved from Category 4d to Category 3b.

Details about the 2017 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/940

Monitoring and Methods
Assessment Key Dates
10/9/2017 Fish Kill
Methods
120 Surveys of fish and game biologists/other professionals
140 Incidence of spills and/or fish kills
150 Monitoring data more than 5 years old
330 Fish surveys