Brushy Creek Lake IA 04-UDM-1276

Webster Co. in S34 T88N R27W; 5 miles E. of Lehigh

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
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Cycle: 2024
Release Status: Final
Overall IR: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trophic: Eutrophic
Trend: Stable
Created: 11/1/2023 8:13:17 AM
Updated: 5/8/2024 10:29:00 AM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

Slight

Status

Delisted

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2012

Impairment Rationale

Single-sample maximum criterion exceeded in significantly > 10% of samples

Cycle Delisted

2024

Delisting Rationale

TMDL preparation and approval

Data Source

TMDL monitoring: Iowa DNR

Class BLW

Aquatic Life - Lakes and wetlands

WINOFI

Exotic/Invasive Species

Support Level

Further Investigation Needed

Impairment Code

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

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Moderate

Cycle Added

2016

Impairment Rationale

Adverse impacts on plant/animal communities

Data Source

Biological monitoring: Iowa DNR Fisheries

Class HH

Human Health -

WINOFI

Metals: Mercury

Support Level

Further Investigation Needed

Impairment Code

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

Cause Magnitude

Slight

Status

New

Source

Atmospheric Deposition

Source Confidence

Low

Cycle Added

2024

Impairment Rationale

Potential Impairment

Data Source

Fish contaminant monitoring: Iowa DNR

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use was assessed (monitored) as “not supported” due to violations of the state's indicator bacteria criteria. The Class BLW use was assessed (evaluated) as “WINOFI” due to invasive species. The Class HH use was assessed as “WINOFI” based on fish tissue sampling 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 2020-2022	21940001	Brushy Creek Beach
Iowa DNR	6	WQ	CY 2018-2022	22940002	Brushy Creek Lake
Iowa DNR	6	FT	See Below	1283	Brushy Creek Lake	Brushy Creek State Park / Recreation Area

Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2020/ 2021/2022)

2020 Geometric Mean

2021 Geometric Mean

2022 Geometric Mean

Violates Annual Geometric Mean?

# 2020 SSM violations / SSM Violations needed for impairment

# 2021 SSM violations / SSM Violations needed for impairment

# 2022 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

21940001

14/14/13

0 / 4

1 / 4

4 / 4

YES

Mon

Not

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
21940001	6	30 / 2	7.8	9.2	8.4	3	6	NO	Mon	Full
22940002	6	15 / 5	7.4	8.9	8.2	0	4	NO	Mon	Full

Class A1 - Lake TSI's:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Minimum Value	Maximum Value	Median Value	Median TSI Violation?	Assessment Type	Support Level
22940002	6	Chlorophyll a TSI	15 / 5	26	73	53	NO	Mon	Full
22940002	6	Secchi TSI	15 / 5	28	63	51	NO	Mon	Full
22940002	6	Total Phosphorus TSI	15 / 5	35	83	59	NA	NA	NA
22940002	6	Inorganic suspended solids	15 / 5	0.6	8.4	1.7	NA	NA	NA

Class BLW - 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
21940001	6	Dissolved Oxygen	30 / 2	5.23	17.79	9.55	0	NA / NA	6	NO	Mon	Full
22940002	6	Dissolved Oxygen	13 / 5	1.2	18.1	9.6	1	NA / NA	4	NO	Mon	Full
21940001	6	pH	30 / 2	7.8	9.2	8.4	3	NA / NA	6	NO	Mon	Full
22940002	6	pH	15 / 5	7.4	8.9	8.2	0	NA / NA	4	NO	Mon	Full
21940001	6	Temperature	30 / 2	16.5	27.4	24.1	0	NA / NA	6	NO	Mon	Full
22940002	6	Temperature	15 / 5	11.4	29.1	20.4	0	NA / NA	4	NO	Mon	Full

Class BLW - Lake Planktonic Cyanobacteria:

Site ID	Data Source ID	# Samples	Maximum Cyanobacteria Wet Mass	Maximum Cyanobacteria % Composition	Median Cyanobacteria Wet Mass	Median Cyanobacteria % Composition	Median Cyanobacteria Concentration = 75th Percentile	Assessment Type	Support Level
22940002	6	7	4.140404746	72%	0.320046697	16%	NO	Evaluated	NA

Class BLW - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	>1 Acute / Chronic Violation	Assessment Type	Support Level
22940002	6	Ammonia	15 / 5	0.323	0.11	0.1	0 / 0	NO	Mon	Full

Class HH - Fish Tissue Sampling:

Site ID	Biopart	Year	Species	# in sample / # of samples	Avg Length (cm)	(Avg) Hg (ppm)	Chlordane (ppm)	Sum PCBs (ppm)
1283	fillet	2013	channel catfish	3	49.3	0.05	<0.2	<0.6
1283	tissue plug	2016	largemouth bass	5	38.6	0.05
1283	tissue plug	2021	muskie	1		0.368
Support Level	WINOFI

Additional Information:

The Class B(LW) (aquatic life) use was assessed (evaluated) as “not supported” based on information from the DNR Fisheries Bureau and results from the ISU lake surveys. Information from the DNR Fisheries Bureau indicated this lake had excessive growth of curly-leaf pondweed and brittle naiad. Additionally, Zebra mussel veligers were recently discovered in the lake.

Monitoring and Methods

Assessment Key Dates

5/15/2018

Monitoring Start

8/30/2022

Monitoring End

8/29/2013

Fish Tissue Monitoring

8/30/2016

Fish Tissue Monitoring

4/9/2021

Fish Tissue Monitoring

4/6/2022

TMDL Completed

Methods

120

Surveys of fish and game biologists/other professionals

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

260

Fish tissue analysis

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)

420

Indicator bacteria monitoring