2020 assessment for Viking Lake

Viking Lake IA 05-NOD-1407

Montgomery County S6T71NR36W 4 mi. E of Stanton.

2020
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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Overall IR

2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.

Trophic

Eutrophic

Trend

Stable

Created

8/25/2020 3:12:48 PM by

Updated

10/15/2020 7:45:18 AM by

Use Support

Class A1

Recreation - Primary contact

Fully Supported

Class BLW

Aquatic Life - Lakes and wetlands

Fully Supported

Class C

Drinking Water -

Not Assessed

Class HH

Human Health -

Fully Supported

General Use

General Use water -

Not Assessed

303(d) Delistings for this Cycle

Cycle Added	Class	Cause	Data Source	Rationale
2006	Class A1	Bacteria: Indicator Bacteria- E. coli	Beach monitoring: Iowa DNR WQMA	New data: WQ improvement (chemical / physical / bacterial)

Documentation

Assessment Summary

The Class A1 uses are assessed (monitored) as “fully supported.” The Class BLW uses are assessed (monitored) as “fully supported.” The Class C (drinking water) uses remain “not assessed” due to a lack of enough information upon which to base an assessment. Class HH uses are assessed (monitored) as “fully supported” based on fish tissue sampling.

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	21690001	Viking Lake Beach (Viking Lake State Park)
Iowa DNR	6	WQ	CY 2014-2018	22690001	Viking Lake	Lake Deep Point
Iowa DNR		FT	See Below	339	Viking Lake

Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2016 Geometric Mean	2017 Geometric Mean	2018 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
21690001	6	45 / 3	26.67	18.05	13.79	No	4	9%	NO	Monitored	Full

Viking Lake was assessed as "partially supported" for the 2012 assessment/listing cycle. Based on DNR’s assessment methodology 2 consecutive assessment/listing cycles without violations of the geometric mean criterion and without significantly greater than 10% of the samples violating the single-sample maximum criterion are necessary to propose delisting based on bacteria violations. There were no violations of the geometric mean criterion and there were less than 10% of the samples exceeding the single-sample maximum criterion for the 2018or current 2020assessment listing cycle. Therefore, the impairment for indicator bacteria is suggested for delisting for the 2020 assessment/listing cycle.

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
22690001	6	14 / 5	8.8	8.3	8.2	0	0%	NO	Monitored	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
22690001	6	Chlorophyll a TSI	15 / 5	36	80	64	NO	Monitored	Full
22690001	6	Secchi TSI	15 / 5	50	70	63	NO	Monitored	Full
22690001	6	Total Phosphorus TSI	15 / 5	56	75	63	NA	NA	NA
22690001	6	Inorganic suspended solids	15 / 5	0.3	9.8	2.8	NA	NA	NA

Class BLW - 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
22690001	6	Ammonia	14 / 5	0.114	0.02	0.01	0 / 0	0% / 0%	NO	Monitored	Full
22690001	6	Dissolved oxygen	15 / 5	11.88	8.03	7.6	NA / 0	NA / 0%	NO	Monitored	Full
22690001	6	pH	14 / 5	8.8	8.3	8.2	0 / NA	0% / NA	NO	Monitored	Full
22690001	6	Temperature	15 / 5	30.7	24.72	24.5	0 / 0	0% / 0%	NO	Monitored	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 Wet Mass = 75th Percentile	Assessment Type	Support Level
22690001	6	11	66.621	99.1 %	20.153	88.5 %	NO	Evaluated	NA

Class C - Conventional Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
22690001	6	Inorganic nitrogen (nitrate and nitrite)	15 / 5	0.1	0.03	0.03	0	0%	NO	Monitored	Full

The Class C uses are not assessed due to the lack of data sufficient for developing a valid assessment of support of the Class C uses.

Class HH - Fish Tissue Sampling:

Site ID

Date

Species Name

Biopart

# in sample

chlordane result

chlordane violation?

PCBs result

PCBs violation?

Hg result

Hg violation?

Assessment Type

Support Level

339

8/18/15

largemouth bass

plug

0.164

Monitored

Full

339

9/2/15

channel catfish

fillet

<0.02

<0.06

0.03

Monitored

Full

Monitoring and Methods

Assessment Key Dates

6/16/2014

Fixed Monitoring Start Date

8/27/2018

Fixed Monitoring End Date

9/2/2015

Fish Tissue Monitoring

8/18/2015

Fish Tissue Monitoring

Methods

120

Surveys of fish and game biologists/other professionals

222

Non-fixed-station monitoring (conventional during key seasons and flows)

260

Fish tissue analysis

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)

420

Indicator bacteria monitoring