Lake Miami IA 04-LDM-1016

Monroe County S20T73NR17W 5 mi. SE of Lovilia.

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.

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Cycle: 2024
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trophic: Hypereutrophic
Trend: Stable
Created: 11/1/2023 8:13:01 AM
Updated: 2/5/2024 8:06:43 AM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Turbidity

Support Level

Not Supported

Impairment Code

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

Cause Magnitude

Moderate

Status

Continuing

Source

Agriculture

Source Confidence

Moderate

Cycle Added

2002

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Iowa DNR-lakes

Class BLW

Aquatic Life - Lakes and wetlands

Not Supported

Turbidity: Siltation/Turbidity

Support Level

Not Supported

Impairment Code

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

Cause Magnitude

Moderate

Status

Continuing

Source

Agriculture

Source Confidence

Moderate

Cycle Added

2002

Impairment Rationale

Adverse impacts on plant/animal communities

Data Source

Biological monitoring: Iowa DNR Fisheries

Class HH

Human Health -

Not Supported

Fish Consumption Advisory: Mercury

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

High

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Moderate

Cycle Added

2012

Impairment Rationale

Fish consumption advisory in effect: no more than 1 meal/week

Data Source

Fish contaminant monitoring: Iowa DNR

TMDL Priority

Tier IV

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2022	Class BLW	pH	Ambient monitoring: Iowa DNR-lakes	New data: WQ improvement (chemical / physical / bacterial)
2022	Class A1	pH	Ambient monitoring: Iowa DNR-lakes	New data: WQ improvement (chemical / physical / bacterial)

Documentation

Assessment Summary

The Class A1 use was assessed (monitored) as “not supported” due to poor water clarity caused by non-algal turbidity (IR 4a). The Class BLW use was assessed as “not supported” (IR 4a) due to reduced water transparency related to the presence of common carp populations, and sedimentation problems in the lake. The Class HH (fish consumption) use remains assessed (monitored) as “not supported” (IR 5a) based on the results of fish tissue monitoring and the existence of a one meal per week consumption advisory for mercury in this lake. Note: A TMDL for siltation and nutrients at Lake Miami was prepared by DNR and approved by EPA in 2001. Because the Section 303(d) impairment for pH and mercury in fish tissue was not addressed by the TMDL, this waterbody was placed in IR Category 5a (impaired; TMDL needed) for the current assessment/listing cycle.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2018-2022	22680001	Lake Miami Max Depth
Iowa DNR	6	FT	See Below	1140	Lake Miami	ESE of Lovilia

Class A1 - Indicator Bacteria: No Data

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
22680001	6	15 / 5	7.5	9.6	8.5	3	4	NO	Mon	Full

Lake Miami was assessed as "not supported" for the 2022 assessment/listing cycle due to frequent violations of the state Class A1 criterion for pH. Based on DNR’s assessment methodology the current assessment/listing cycles must have fewer violations of the criterion based on the minimum required by the 10% Rule to propose delisting pH. There were less than 10% of the samples exceeding the single-sample maximum criterion for the 2024 assessment/listing cycle. Therefore, the impairment for pH is suggested for delisting for the 2024 assessment/listing cycle.

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
22680001	6	Chlorophyll a TSI	15 / 5	37	84	64	NO	Mon	Full
22680001	6	Secchi TSI	15 / 5	39	81	73	YES	Mon	Not
22680001	6	Total Phosphorus TSI	15 / 5	54	85	74	NA	NA	NA
22680001	6	Inorganic suspended solids	15 / 5	0.6	16	1.9	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
22680001	6	Dissolved Oxygen	14 / 5	4.9	21.3	9.3	1	NA / NA	4	NO	Mon	Full
22680001	6	pH	15 / 5	7.5	9.6	8.5	3	NA / NA	4	NO	Mon	Full
22680001	6	Temperature	15 / 5	20.6	29.8	25.3	0	NA / NA	4	NO	Mon	Full

Lake Miami was assessed as "not supported" for the 2022 assessment/listing cycle due to frequent violations of the state Class A1 criterion for pH. Based on DNR’s assessment methodology the current assessment/listing cycles must have fewer violations of the criterion based on the minimum required by the 10% Rule to propose delisting pH. There were less than 10% of the samples exceeding the single-sample maximum criterion for the 2024 assessment/listing cycle. Therefore, the impairment for pH is suggested for delisting for the 2024 assessment/listing cycle.

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
22680001	6	4	38.22681179	98%	11.7563415	65%	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
22680001	6	Ammonia	15 / 5	0.49	0.1	0.06	0 / 1	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)
1140	fillet	2010	largemouth bass	5	NA	0.394
1140	fillet	2009	largemouth bass	4	NA	0.353
Support Level	Not	A one meal/week mercury consumption advisory for largemouth bass exists on this segment. Based on IR Methodology, the Class HH (fish consumption) use was assessed as “not supported.”

Monitoring and Methods

Assessment Key Dates

5/22/2018

Monitoring Start

9/5/2022

Monitoring End

10/26/2009

Fish Tissue Monitoring

7/27/2010

Fish Tissue Monitoring

1/28/2002

TMDL Completed

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

260

Fish tissue analysis

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)