Hewitt Creek IA 01-NMQ-109

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

This is a DRAFT assessment

Draft assessments may change without notice

Open Data Collection Period Modal

For purposes of developing stream/river water quality assessments for integrated reporting, three years of water quality data are typically used for both conventional pollutant parameters (e.g., indicator bacteria) and the less frequently monitored toxic parameters (e.g., toxic metals). Since the 2004 IR cycle, DNR has used a three-year data gathering period for streams, rivers, and beaches. For most assessments, the use of three years of data increases the number of samples upon which the decision on use support is based and helps address the problem of weather-related year-to-year fluctuations in water quality.

Due to the lower sampling frequency in Iowa’s ambient lake, biological, fish kill, and fish tissue monitoring programs, five years of data are used for developing IR assessments and for identifying Section 303(d) listings.

Data Type	Data Timeframe
Beach Sampling Data	CY 2022 - 2024
Stream/River Water Quality Data	CY 2022 - 2024
Lake Water Quality Data	CY 2020 - 2024
Biological Sampling Data	CY 2020 - 2024*
Fish Kill Data	CY 2020 - 2024
Fish Tissue Sampling Data	CY 2020 - 2024
Continuous Dissolved Oxygen Sampling Data	CY 2020 - 2024
*Biological sites sampled in both 2019 and 2023 were also assessed.

Open Segment Map
View 2026 assessment summary page

Cycle: 2026
Current Phase: Public Comment
Overall IR: 3 - Insufficient data exist to determine whether any designated uses are met.
Trend: Stable
Created: 10/27/2025 3:11:10 PM
Updated: 2/11/2026 1:00:08 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

WINOFI

Fish Kill: Caused By Animal Waste

Support Level

Further Investigation Needed

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

Potential Impairment

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 on DNR IR methodology this BWW2 fish kill assessment was moved from Category 4d to Category 3b after five years (2022) and will be moved to Category 3a (not assessed) after another five years (2027).

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