West Lake (Osceola) IA 04-LDM-1082

Clarke County S13T72NR26W approx 2 mi W of Osceola.

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 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

Open Segment Map
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Cycle: 2022
Release Status: Final
Overall IR: 1 - All designated uses are met.
Trophic: Eutrophic
Trend: Stable
Created: 12/28/2021 10:22:44 AM
Updated: 1/5/2022 1:24:11 PM

Use Support

Class BLW

Aquatic Life - Lakes and wetlands

Fully Supported

Class C

Drinking Water -

Fully Supported

Class HH

Human Health -

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class BLW use was assessed (monitored) as “fully supported.” The Class C use was assessed (monitored) as "fully supported" based on atrazine and Inorganic nitrogen monitoring results. The Class HH (fish consumption) use was assessed as "fully supported" based on fish tissue sampling data. Note: A TMDL for atrazine at West Lake (Osceola) was prepared by DNR and approved by EPA in 2002.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2016-2020	22200002	West Lake Osceola
Iowa DNR	6	FT	See Below	340	West Lake	Osceola

Class BLW - Conventional Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	# Violations	# Acute / Chronic Violations	Violations needed for impairment	Violates Significantly >10% Rule?	Assessment Type	Support Level
22200002	6	Ammonia	15 / 5	0.0003	0.4724	0.12	NA	0 / 0	4	NO	Monitored	Full
22200002	6	Dissolved Oxygen	14 / 5	1.7	11.1	7.1	3	NA / NA	4	NO	Monitored	Full
22200002	6	pH	15 / 5	6.8	8.9	8.1	0	NA / NA	4	NO	Monitored	Full
22200002	6	Temperature	15 / 5	17.4	28.6	23.7	0	NA / NA	4	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 Concentration = 75th Percentile	Assessment Type	Support Level
22200002	6	5	9.89	98.0%	2.56	39.0%	NO	Evaluated	NA

Class C - Conventional Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	Median Value	# Violations	Violates Significantly >10% Rule?	Assessment Type	Support Level
22200002	6	Inorganic nitrogen (nitrate and nitrite)	15 / 5	0.02	1.84	0.43	0.03	0	NO	Monitored	Full
22200002	6	pH	15 / 5	6.8	8.9	8.1	8.3	0	NO	Monitored	Full

Class C - Toxic Parameters: Syngenta “Iowa Voluntary Atrazine Monitoring Program” from 2010 through 2012

Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	Number of Non - Detects	Mean Value > Criterion or MCL	Assessment Type	Support Level
Atrazine	63 / 2	2.93	1.45	NA	NA	No	Monitored	Full

Class HH - Fish Tissue Sampling:

Site ID	Biopart	Year	Species	# in sample / # of samples	Avg Length (cm)	(Avg) Hg (ppm)	Chlordane (ppm)	Sum PCBs (ppm)
340	fillet	2013	channel catfish	5	44.2	0.05	0.2	0.15
340	tissue plug	2014	largemouth bass	4	43.4	0.145
Support Level	Full

Monitoring and Methods

Assessment Key Dates

5/23/2016

Fixed Monitoring Start Date

9/8/2020

Fixed Monitoring End Date

8/15/2013

Fish Tissue Monitoring

7/1/2014

Fish Tissue Monitoring

10/28/2002

TMDL Completed

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)