Unnamed Tributary to Black Hawk Lake (aka Wall Lake Inlet) IA 04-RAC-6635

from confluence with unnamed trib in SW 1/4 S 23 T-86N R-36W Sac Co. to headwaters in NW 1/4 NW 1/4 S7 T-85N R-35W Carroll 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 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: 1 - All designated uses are met.
Trend: Unknown
Created: 11/1/2023 8:13:12 AM
Updated: 12/20/2023 2:56:39 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Fully Supported

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as “fully supported" based on the results of limited water quality monitoring data. The presumptive Class BWW1 use was assessed as “fully supported" based on results of limited chemical/physical monitoring.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2018-2018	13810004	Unnamed Tributary at 100th St. (site BHL-13)
Iowa DNR	6	WQ	CY 2018-2018	14000119	Unnamed Tributary at 380th (BHL-09)

Presumptive Class A1 - Indicator Bacteria: No Data

Presumptive Class A1 – 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
13810004	6	15 / 1	6.8	8.1	7.5	0	4	NO	Monitored	Full
14000119	6	15 / 1	6.9	8.1	7.7	0	4	NO	Monitored	Full

Presumptive Class BWW1 - Binomial 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
13810004	6	Dissolved Oxygen	15 / 1	6.4	15.5	9.2	0	NA / NA	4	NO	Monitored	Full
14000119	6	Dissolved Oxygen	15 / 1	6.9	14.1	9.5	0	NA / NA	4	NO	Monitored	Full
13810004	6	pH	15 / 1	6.8	8.1	7.5	0	NA / NA	4	NO	Monitored	Full
14000119	6	pH	15 / 1	6.9	8.1	7.7	0	NA / NA	4	NO	Monitored	Full
13810004	6	Temperature	15 / 1	4	18.6	14.6	0	NA / NA	4	NO	Monitored	Full
14000119	6	Temperature	15 / 1	3.1	20.1	14.6	0	NA / NA	4	NO	Monitored	Full

Monitoring and Methods

Assessment Key Dates

4/16/2018

Monitoring Start

10/31/2018

Monitoring End

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring