2020 assessment for Lake Anita

Lake Anita IA 05-NSH-1435

Cass County S32T77NR34W 1/2 mi S Anita.

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

5 - Water is impaired or threatened and a TMDL is needed.

Trophic

Eutrophic

Trend

Stable

Created

8/26/2020 11:35:37 AM by

Updated

10/15/2020 7:47:54 AM by

Use Support

Class A1

Recreation - Primary contact

Partially Supported

Algal Growth: Cyanobacteria

Support Level

Partially Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

303(d) Listing Status

Continuing

Source

Natural: Internal Nutrient Recycling (Primarily Lakes)

Source Confidence

Moderate

Cycle Added

2010

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Iowa DNR-lakes

TMDL Priority

Tier I

Class BLW

Aquatic Life - Lakes and wetlands

Fully Supported

Class HH

Human Health -

Fully Supported

General Use

General Use water -

Not Assessed

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 uses are assessed (monitored) as “partially supported” due to algae blooms that violate Iowa's narrative criteria protecting against aesthetically objectionable conditions also cause an impairment at this lake. The Class BLW uses are assessed (monitored) as “fully supported.” 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	21150001	Lake Anita Beach (Lake Anita State Park)
Iowa DNR	6	WQ	CY 2014-2018	22150002	Lake Anita	Lake Deep Point
Iowa DNR	6	WQ	CY 2014-2014	14000153	Lake Anita	TMDL North East Arm(ANITA2)
Iowa DNR	6	WQ	CY 2014-2014	14000154	Lake Anita	TMDL South East Arm(ANITA1)
Iowa DNR		FT	See Below	100	Lake Anita

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
21150001	6	31 / 3	29.62	30.14	22.54	No	3	10%	NO	Monitored	Full

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
22150002	6	15 / 5	8.98	8.38	8.3	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
14000153	6	Chlorophyll a TSI	14 / 1	41	78	67	YES	Evaluated	Not
14000154	6	Chlorophyll a TSI	14 / 1	37	78	67	YES	Evaluated	Not
22150002	6	Chlorophyll a TSI	29 / 5	36	79	66	YES	Monitored	Not
22150002	6	Secchi TSI	15 / 5	47	73	67	YES	Monitored	Not
14000153	6	Total Phosphorus TSI	14 / 1	57	76	67	NA	NA	NA
14000154	6	Total Phosphorus TSI	14 / 1	53	76	65	NA	NA	NA
22150002	6	Total Phosphorus TSI	29 / 5	49	79	66	NA	NA	NA
22150002	6	Inorganic suspended solids	15 / 5	0.3	30	2.9	NA	NA	NA

The level of inorganic suspended solids was relatively low at Lake Anita, and does not suggest water quality problems due to non-algal turbidity.

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
22150002	6	Ammonia	15 / 5	0.335	0.09	0.03	0 / 0	0% / 0%	NO	Monitored	Full
22150002	6	Dissolved oxygen	15 / 5	10.47	7.85	8.1	NA / 1	NA / 7%	NO	Monitored	Full
22150002	6	pH	15 / 5	8.98	8.38	8.3	0 / NA	0% / NA	NO	Monitored	Full
22150002	6	Temperature	15 / 5	28.5	24.25	23.4	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
22150002	6	11	160.379	98.4 %	42.704	93.2 %	YES	Evaluated	3b

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

100

6/19/17

largemouth bass

plug

0.240

Monitored

Full

100

8/11/09

snapping turtle

shoulder

<0.03

<0.09

0.171

Evaluated

Full

Monitoring and Methods

Assessment Key Dates

4/17/2014

Fixed Monitoring Start Date

8/30/2018

Fixed Monitoring End Date

8/11/2009

Fish Tissue Monitoring

6/19/2017

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