Big Spirit Lake IA 06-LSR-1655

Dickinson County S33T100NR36W at Spirit Lake

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: 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: 8/31/2020 1:14:28 PM
Updated: 10/15/2020 10:58:09 AM

Use Support

Class A1

Recreation - Primary contact

Fully Supported

Class BLW

Aquatic Life - Lakes and wetlands

WINOFI

Fish Kill: Due To Natural Causes

Support Level

Further Investigation Needed

Impairment Code

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

Cause Magnitude

High

Status

Continuing

Source

Natural: Ordinary Stratification and Bottom-Water Hypoxia/Anoxia

Source Confidence

Low

Cycle Added

2010

Impairment Rationale

Non Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

Algal Growth: Cyanobacteria

Support Level

Further Investigation Needed

Impairment Code

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

Cause Magnitude

Slight

Status

New

Source

Agriculture

Source Confidence

Low

Cycle Added

2020

Impairment Rationale

Adverse impacts on plant/animal communities

Data Source

Ambient monitoring: Iowa DNR-lakes

Class C

Drinking Water -

Not Assessed

Class HH

Human Health -

Not Assessed

General Use

General Use water -

Not Assessed

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2008	Class A1	Bacteria: Indicator Bacteria- E. coli	Ambient monitoring: Iowa DNR-lakes	New data: WQ improvement (chemical / physical / bacterial)

Documentation

Assessment Summary

The Class A1 use is assessed (monitored) as “fully supported.” The Class BLW use is assessed (evaluated) as “partially supported” based on the results of fish kill investigations. In Addition, the Class BLW use is assessed (evaluated) as “partially supported” due to cyanobacteria blooms. The Class C use is “not assessed” due to a lack of enough information upon which to base an assessment. All other designated uses were “not assessed”.

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	21300005	Crandall's Beach (Crandall's Beach)
Iowa DNR	6	WQ	CY 2016-2017	21300006	Marble Beach (Marble Beach State Park)
Iowa DNR	6	WQ	CY 2016-2016	21300007	Orleans Beach Area Beach
Iowa DNR	6	WQ	CY 2014-2018	22300014	Big Spirit 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
21300005	6	29 / 3	12.41	34.69	23.75	No	3	10%	NO	Monitored	Full
21300006	6	21 / 2	16.65	10.6	NA	No	1	5%	NO	Monitored	Full
21300007	6	13 / 1	15.27	NA	NA	No	0	0%	NO	Monitored	Full

Big Spirit Lake was assessed as "partially supported" for the 2008 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. Upon reevaluation, there were no violations of the geometric mean criterion and there were total violations of the samples exceeding the single-sample maximum criterion less than the significantlygreater than 10% allowed forthe 2018 or current 2020 assessment 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
22300014	6	15 / 5	8.7	8.5	8.5	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
22300014	6	Chlorophyll a TSI	15 / 5	31	63	53	NO	Monitored	Full
22300014	6	Secchi TSI	15 / 5	34	65	56	NO	Monitored	Full
22300014	6	Total Phosphorus TSI	15 / 5	34	68	57	NA	NA	NA
22300014	6	Inorganic suspended solids	15 / 5	0.3	13	1.1	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
22300014	6	Ammonia	15 / 5	0.053	0.01	0.01	0 / 0	0% / 0%	NO	Monitored	Full
22300014	6	Dissolved oxygen	15 / 5	18.2	10.4	9.5	NA / 0	NA / 0%	NO	Monitored	Full
22300014	6	pH	15 / 5	8.7	8.5	8.5	0 / NA	0% / NA	NO	Monitored	Full
22300014	6	Temperature	15 / 5	26.3	21.9	22.5	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
22300014	6	11	300.219	99.4 %	44.145	97.1 %	YES	Evaluated	3b

Class BLW - Fish Kill:

The Class BLW uses are assessed (evaluated) as “partially supported” due to fish kills that occurred inAugust of 2011, inJuly 2018, and inAugust of 2018. Because the cause of the fish kill was not identified, or the fish kill was attributed to a non-pollutant cause (e.g., winterkill), the assessment type is “evaluated.” Segments assessed using “evaluated” assessments are placed in Category 3b and are added to the state list of waters in need of further investigation. If no additional fish kills are reported in the segment for a 10 year period, the Category will be changed from 3b to 3a (water not assessed).

Details about the fish kills can be found here:https://programs.iowadnr.gov/fishkill/Events/849,https://programs.iowadnr.gov/fishkill/Events/931, andhttps://programs.iowadnr.gov/fishkill/Events/989,

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
22300014	6	Inorganic nitrogen (nitrate and nitrite)	15 / 5	1.1	0.12	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 - No Data

Monitoring and Methods

Assessment Key Dates

6/3/2014

Fixed Monitoring Start Date

9/3/2018

Fixed Monitoring End Date

7/20/2018

Fish Kill

8/16/2011

Fish Kill

8/13/2018

Fish Kill

Methods

120

Surveys of fish and game biologists/other professionals

222

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

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)

420

Indicator bacteria monitoring