Little River Watershed Lake IA 05-GRA-1358

Decatur County S19T69NR25W approx 2 mi NW of Leon.

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: 5 - Water is impaired or threatened and a TMDL is needed.
Trophic: Eutrophic
Trend: Stable
Created: 8/20/2020 2:53:14 PM
Updated: 10/14/2020 2:44:14 PM

Use Support

Class A1

Recreation - Primary contact

Partially Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Partially Supported

Impairment Code

5* - 303(d)-impaired last cycle; fully supporting this cycle; potential de-listing.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2014

Impairment Rationale

Single-sample maximum criterion exceeded in significantly > 10% of samples

Data Source

Beach monitoring: Iowa DNR city/county

TMDL Priority

Tier II

Class BLW

Aquatic Life - Lakes and wetlands

Fully Supported

Class C

Drinking Water -

Not Assessed

Class HH

Human Health -

Partially Supported

Metals: Mercury

Support Level

Partially Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

New

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2020

Impairment Rationale

Potential fish consumption advisory; additional sampling needed

Data Source

Fish contaminant monitoring: Iowa DNR

TMDL Priority

Tier IV

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use is assessed (monitored) as “not supported” due to violations of the state's water quality criteria for indicator bacteria. The Class BLW use is assessed (monitored) as “fully supported.” The Class C use remains “not assessed” due to a lack of enough information upon which to base an assessment. Class HH use is assessed as (monitored) "partially supporting" due to the potential of a fish consumption advisory caused by mercury. Note: A TMDL for turbidity and total phosphorus at Little River Watershed Lake was prepared for and approved by EPA in March 2014. Because the indicator bacteria and mercury impairments at Little River Watershed Lake was not addressed in this TMDL, it will remain listed in category 5a; impaired - TMDL needed.

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 2014-2016	21270002	Little River Recreation Area Beach
Iowa DNR	6	WQ	CY 2014-2018	22270001	Little River Lake	Lake Deep Point
Iowa DNR		FT	See Below	75	Little River Lake

Class A1 - Indicator Bacteria: Historical 2018 Assessment

Site ID	Data Source ID	# Samples / # Years	2014 Geometric Mean	2015 Geometric Mean	2016 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
21270002	6	40 / 3	12	52	7	No	3	8%	NO	Monitored	Full

In the 2016 assessment/listing cycle, the Class A1 uses were listed as "partially supported" due to geometric mean and single-sample maximum exceedances. According to DNR's methodology, lakes must meet water quality standards for two consecutive assessment/listing cycles to suggest de-listing. Therefore, the Class A1 uses will remain listed as "partially supported" for the current 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
22270001	6	15 / 5	9.1	8.3	8.1	2	13%	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
22270001	6	Chlorophyll a TSI	15 / 5	31	75	58	NO	Monitored	Full
22270001	6	Secchi TSI	15 / 5	42	73	62	NO	Monitored	Full
22270001	6	Total Phosphorus TSI	15 / 5	55	81	65	NA	NA	NA
22270001	6	Inorganic suspended solids	15 / 5	0.3	16	2	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
22270001	6	Ammonia	15 / 5	0.3	0.06	0.02	0 / 0	0% / 0%	NO	Monitored	Full
22270001	6	Dissolved oxygen	15 / 5	14.3	7.5	6.9	NA / 3	NA / 20%	NO	Monitored	Full
22270001	6	pH	15 / 5	9.1	8.3	8.1	2 / NA	13% / NA	NO	Monitored	Full
22270001	6	Temperature	15 / 5	27.7	22.9	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
22270001	6	11	381.425	100 %	23.741	88.8 %	YES	Evaluated	3b

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
22270001	6	Inorganic nitrogen (nitrate and nitrite)	15 / 5	0.5	0.14	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

5/23/17

largemouth bass

plug

0.357

Yes

Monitored

Partial

6/29/16

largemouth bass

plug

0.453

Yes

Monitored

Partial

7/18/16

channel catfish

fillet

<0.02

<0.06

0.09

Monitored

Full

Monitoring and Methods

Assessment Key Dates

5/28/2014

Fixed Monitoring Start Date

8/16/2018

Fixed Monitoring End Date

3/27/2014

TMDL Completed

7/18/2016

Fish Tissue Monitoring

6/29/2016

Fish Tissue Monitoring

5/23/2017

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

270

PWS chemical monitoring (ambient water)

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)

420

Indicator bacteria monitoring