Blue Lake IA 06-WEM-1728

Alternate name(s) for this segment: Lewis and Clark Lake

Monona County S35T84NR46W 2 mi. W of Onawa.

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
View assessment methodology in new window

Cycle: 2020
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: 9/1/2020 12:58:12 PM
Updated: 10/15/2020 11:08:12 AM

Use Support

Class A1

Recreation - Primary contact

Partially Supported

Algal Growth: Chlorophyll a

Support Level

Partially Supported

Impairment Code

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

Cause Magnitude

Moderate

Status

Continuing

Source

Agriculture

Source Confidence

Moderate

Cycle Added

2004

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Iowa DNR-lakes

Turbidity

Support Level

Partially Supported

Impairment Code

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

Cause Magnitude

High

Status

Continuing

Source

Other: Sediment Resuspension

Source Confidence

High

Cycle Added

2004

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Iowa DNR-lakes

Class BLW

Aquatic Life - Lakes and wetlands

WINOFI

Exotic/Invasive Species: Fish 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

N/A

Cycle Added

2010

Impairment Rationale

Adverse impacts on plant/animal communities

Data Source

Biological monitoring: Iowa DNR Fisheries

Class HH

Human Health -

Not Assessed

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 uses are assessed (monitored) as “not supported” due to poor water transparency and aesthetically objectionable conditions caused by algae blooms. The Class BLW uses are assessed (monitored) as “fully supported.” All other designated uses are “not assessed.” Note: A TMDL for the algae and turbidity impairments at Blue Lake was prepared by DNR and approved by EPA in January 2009. Because the 2009 TMDL includes all of the impairments identified for the current assessment/listing cycle, this lake will remain in IR Category 4a (impaired; TMDL approved.)

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	21670001	Blue Lake Beach (Lewis & Clark State Park)
Iowa DNR	6	WQ	CY 2014-2018	22670002	Blue 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
21670001	6	36 / 3	16.8	46.08	28.74	No	4	11%	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
22670002	6	15 / 5	8.56	8.29	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
22670002	6	Chlorophyll a TSI	15 / 5	46	76	61	NO	Monitored	Full
22670002	6	Secchi TSI	15 / 5	63	77	70	YES	Monitored	Not
22670002	6	Total Phosphorus TSI	15 / 5	53	76	70	NA	NA	NA
22670002	6	Inorganic suspended solids	15 / 5	0.4	21	10.8	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
22670002	6	Ammonia	15 / 5	0.529	0.14	0.06	0 / 0	0% / 0%	NO	Monitored	Full
22670002	6	Dissolved oxygen	15 / 5	11.7	9.3	9	NA / 0	NA / 0%	NO	Monitored	Full
22670002	6	pH	15 / 5	8.56	8.29	8.3	0 / NA	0% / NA	NO	Monitored	Full
22670002	6	Temperature	15 / 5	28	22.9	24.1	0 / 0	0% / 0%	NO	Monitored	Full

Class BLW - Additional Information:

Information from the DNR Fisheries Bureau suggests that Blue Lake has a poor recreational fishery and a large carp population.The Class BLW uses are assessed (evaluated) as “partially supported” based on information from the DNR Fisheries Bureau.

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
22670002	6	10	169.709	90.3 %	7.868	43.25 %	NO	Evaluated	NA

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

5/21/2014

Fixed Monitoring Start Date

8/28/2018

Fixed Monitoring End Date

1/2/2009

TMDL Completed

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