Dry Run (South Branch) IA 02-CED-2062

mouth (T89N R14W Sec13) to headwaters (T88N R14W Sec9)

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 2020 - 2022
Stream/River Water Quality Data	CY 2020 - 2022
Lake Water Quality Data	CY 2018 - 2022
Biological Sampling Data	CY 2018 - 2022*
Fish Kill Data	CY 2018 - 2022
Fish Tissue Sampling Data	CY 2018 - 2022
Continuous Dissolved Oxygen Sampling Data	CY 2018 - 2022
*Biological sites sampled in both 2017 and 2021 were also assessed.

Open Segment Map
View assessment methodology in new window

Cycle: 2024
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 11/1/2023 8:14:08 AM
Updated: 1/8/2024 2:55:58 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Special project/study

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use remains assessed as "not supported” due to levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW2 use remains 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
Iowa DNR	6	WQ	CY 2012-2014	15070003	Dry Run Creek at University Ave	DRC5
Iowa DNR	6	WQ	CY 2012-2014	15070005	South Branch Dry Run Creek at Greenhill Road	DRC8
Iowa DNR	6	WQ	CY 2012-2014	15070007	South Branch Dry Run Creek at Viking Road	DRC10

Presumptive Class A1 - Indicator Bacteria: Historical

Site ID	Data Source ID	# Samples / # Years	2012 Geometric Mean	2013 Geometric Mean	2014 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15070003	6	23 / 3	665	1216	315	Yes	17	74%	Yes	Evaluated	Not
15070005	6	17 / 3	62	995	171	Yes	10	59%	Yes	Evaluated	Not
15070007	6	19 / 3	607	503	144	Yes	9	47%	Yes	Evaluated	Not

Presumptive Class A1 - pH: Historical

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
15070003	6	17 / 2	8.3	8.1	8.1	0	0%	No	Evaluated	Full
15070005	6	15 / 2	8.1	7.7	7.9	1	7%	No	Evaluated	Full
15070007	6	16 / 2	8.4	7.8	7.9	0	0%	No	Evaluated	Full

Class BWW2 - Binomial Parameters: Historical

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	% Acute/ Chronic Violations	Significantly >10% Violations	Assessment Type	Support Level
15070003	6	Chloride	19 / 2	103	72	73	0 / 0	0% / 0%	No	Evaluated	Full
15070005	6	Chloride	16 / 2	85	68	75	0 / 0	0% / 0%	No	Evaluated	Full
15070007	6	Chloride	17 / 2	85	60	58	0 / 0	0% / 0%	No	Evaluated	Full
15070003	6	Dissolved oxygen	19 / 2	12.7	9.7	9	NA / 0	NA / 0%	No	Evaluated	Full
15070005	6	Dissolved oxygen	16 / 2	15	9.2	8.5	NA / 0	NA / 0%	No	Evaluated	Full
15070007	6	Dissolved oxygen	17 / 2	11.8	8.7	8.5	NA / 0	NA / 0%	No	Evaluated	Full
15070003	6	pH	17 / 2	8.3	8.1	8.1	0 / NA	0% / NA	No	Evaluated	Full
15070005	6	pH	15 / 2	8.1	7.7	7.9	1 / NA	7% / NA	No	Evaluated	Full
15070007	6	pH	16 / 2	8.4	7.8	7.9	0 / NA	0% / NA	No	Evaluated	Full
15070003	6	Temperature	19 / 2	23.2	14.5	14.8	0 / 0	0% / 0%	No	Evaluated	Full
15070005	6	Temperature	16 / 2	19.3	13.4	13.2	0 / 0	0% / 0%	No	Evaluated	Full
15070007	6	Temperature	17 / 2	20.3	13.3	13.7	0 / 0	0% / 0%	No	Evaluated	Full

Monitoring and Methods

Assessment Key Dates

8/27/2012

Monitoring Start

10/28/2014

Monitoring End

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

420

Indicator bacteria monitoring