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

2020

Release Status

Final

Data Collection Period

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 2016 - 2018
Stream/River Water Quality Data	CY 2016 - 2018
Lake Water Quality Data	CY 2014 - 2018
Biological Sampling Data	CY 2014 - 2018*
Fish Kill Data	CY 2014 - 2018
Fish Tissue Sampling Data	CY 2014 - 2018
Continuous Dissolved Oxygen Sampling Data	CY 2014 - 2018
*Biological sites sampled in both 2013 and 2017 were also assessed.

Overall IR Category: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend: Unknown

Created: 6/10/2020 9:03:21 AM
Updated: 2/17/2021 11:05:40 AM

Assessment conducted in accordance with Iowa's 2020 IR methodology

Use Support

Class A1

Recreation

Primary contact

Presumptive Use

Not Assessed

Class BWW2

Aquatic Life

Warm Water Type 2

Partially Supported

Impairments

Support Level

Partially Supported

Impairment Code

4d - Pollutant-caused fish kill. No TMDL needed and administrative action taken against responsible party.

Cause Magnitude

High

Status

New

Source

Agriculture: Feedlots

Source Confidence

N/A

Cycle Added

2020

Impairment Rationale

Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

General Use

General Use water

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class BWW2 aquatic life use was assessed as “partially supported” based on a 2017 fish kill investigation. All other designated uses were "not assessed".

Assessment Explanation

Class BWW2 - Fish kill Assessment:

The Class BWW2 aquatic life use assessment based on the 2017 fish kill 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.

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

330

Fish surveys