2020 assessment for Big Hollow Creek

Big Hollow Creek IA 02-ICD-602

mouth (S25 T71N R4W Des Moines Co.) to confluence with unnamed tributary in NW 1/4 S30 T71N R3W Des Moines Co.

2020
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 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.

Open Segment Map
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Overall IR

5 - Water is impaired or threatened and a TMDL is needed.

Trend

Unknown

Created

6/11/2020 9:53:25 AM by

Updated

10/13/2020 8:22:17 AM by

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

Partially Supported

Fish Kill: Caused By Other

Support Level

Partially Supported

Impairment Code

5b - Biological impairment or pollutant-caused fish kill - unknown source. No administrative action.

Cause Magnitude

Moderate

303(d) Listing Status

Continuing

Source

Other: In-lake Management That Has Caused Water Quality Issues

Source Confidence

Moderate

Cycle Added

2016

Impairment Rationale

Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

TMDL Priority

Tier IV

General Use

General Use water -

Not Assessed

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class BWW2 use was assessed as "partially supported" due to 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 use assessment based on the 2014 fish kill placed this segment in Category 5b. 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. Because the source of the pollutant was not identified and/or the enforcement actions taken against the responsible party have not been resolved, the Class BWW2 use was placed in Category 5b. Due to uncertainty regarding the recovery of the aquatic life following the fish kill, any existing fish kill 5b impairment will remain in Category 5b until more recent sampling has shown recovery of the aquatic community or the responsible party has paid restitution.

Details about the 2014 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/919

Monitoring and Methods

Assessment Key Dates

3/11/2014

Fish Kill

Methods

120

Surveys of fish and game biologists/other professionals

140

Incidence of spills and/or fish kills