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 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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Cycle: 2020
Release Status: Final
Overall IR: 1 - All designated uses are met.
Trend: Unknown
Created: 9/23/2020 10:03:52 AM
Updated: 10/9/2020 10:24:05 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Fully Supported

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

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 “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

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2016-2018	13810004	Unnam. Trib. at 100th St. (site BHL-13)
Iowa DNR	6	WQ	CY 2016-2018	14000119	Unnamed Trib at 380th (BHL-09)

Presumptive Class A1 - Indicator Bacteria: No Data

Presumptive Class A1 - pH:

Site ID	Data Source ID	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
13810004	6	45 / 3	8.3	7.5	7.5	0	0%	No	Monitored	Full
14000119	6	46 / 3	8.4	7.7	7.8	0	0%	No	Monitored	Full

Presumptive Class BWW1 - Conventional Parameters:

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
13810004	6	Dissolved oxygen	45 / 3	15.5	9.4	9.1	NA / 0	NA / 0%	No	Monitored	Full
14000119	6	Dissolved oxygen	46 / 3	14.1	9.7	9.5	NA / 0	NA / 0%	No	Monitored	Full
13810004	6	pH	45 / 3	8.3	7.5	7.5	0 / NA	0% / NA	No	Monitored	Full
14000119	6	pH	46 / 3	8.4	7.7	7.8	0 / NA	0% / NA	No	Monitored	Full
13810004	6	Temperature	45 / 3	22	14.7	15.2	0 / 0	0% / 0%	No	Monitored	Full
14000119	6	Temperature	46 / 3	25.4	14.6	14.6	0 / 0	0% / 0%	No	Monitored	Full

Monitoring and Methods

Assessment Key Dates

4/21/2016

Fixed Monitoring Start Date

10/31/2018

Fixed Monitoring End Date

Methods

210

Fixed station physical/chemical monitoring (conventional pollutants only)