Elk Run IA 02-CED-544

mouth (S6 T88N R12W Black Hawk Co.) to confluence with unnamed tributary in S27 T89N R12W Black Hawk Co.

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 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

Open Segment Map
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Cycle: 2022
Release Status: Final
Overall IR: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend: Unknown
Created: 12/22/2021 12:55:40 PM
Updated: 1/13/2022 8:29:19 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

WINOFI

Bacteria: Indicator Bacteria- E. coli

Support Level

Further Investigation Needed

Impairment Code

3b - Use potentially impaired based on an evaluated assessment.

Cause Magnitude

Moderate

Status

New

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2022

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Watershed project monitoring

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as “WINOFI” due to violations of Iowa water quality criteria for indicator bacteria (E. coli). The Class BWW2 use was assessed as "fully supported" based on water quality monitoring data.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
CRWQ	23	WQ	CY 2018-2020	99990057	Elk Run

Presumptive Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2018/ 2019/2020)

2018 Geometric Mean

2019 Geometric Mean

2020 Geometric Mean

Violates Annual Geometric Mean?

# 2018 SSM violations / SSM Violations needed for impairment

# 2019 SSM violations / SSM Violations needed for impairment

# 2020 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

99990057

5/5/5

784

527

1032

YES

5 / NA

Evaluated

WINOFI

Class A – pH:

Site ID	Data Source ID	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	# Violations	Violations needed for impairment	Violates Significantly >10% Rule?	Assessment Type	Support Level
99990057	23	13 / 3	6.01	8.07	7.53	2	4	NO	Monitored	Full

Class BWW2 - Conventional Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	# Violations	# Acute / Chronic Violations	Violations needed for impairment	Violates Significantly >10% Rule?	Assessment Type	Support Level
99990057	23	Chloride	15 / 3	17.7	37.6	26.3	NA	0 / 0	4	NO	Monitored	Full
99990057	23	Dissolved Oxygen	13 / 3	5.1	8.8	7.5	0	NA / NA	4	NO	Monitored	Full
99990057	23	pH	13 / 3	6.01	8.07	7.53	2	NA / NA	4	NO	Monitored	Full
99990057	23	Sulfate	15 / 3	11.1	46.3	30.1	0	NA / NA	4	NO	Monitored	Full
99990057	23	Temperature	15 / 3	9	20	17	0	NA / NA	4	NO	Monitored	Full

Monitoring and Methods

Assessment Key Dates

5/16/2018

Non-fixed Monitoring Start Date

9/29/2020

Non-fixed Monitoring End Date

Methods

220

Non-fixed station physical/chemical monitoring (conventional pollutant only)

420

Indicator bacteria monitoring