Easter Lake IA 04-LDM-1024

Polk County S19T78R23W SE edge of Des Moines.

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 2020 - 2022
Stream/River Water Quality Data	CY 2020 - 2022
Lake Water Quality Data	CY 2018 - 2022
Biological Sampling Data	CY 2018 - 2022*
Fish Kill Data	CY 2018 - 2022
Fish Tissue Sampling Data	CY 2018 - 2022
Continuous Dissolved Oxygen Sampling Data	CY 2018 - 2022
*Biological sites sampled in both 2017 and 2021 were also assessed.

Open Segment Map
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Cycle: 2024
Release Status: Final
Overall IR: 1 - All designated uses are met.
Trophic: Eutrophic
Trend: Improving
Trend Comment: Chlorophyll a and Secchi TSI's continue decline after restoration project.
Created: 11/1/2023 8:13:02 AM
Updated: 2/5/2024 8:09:25 AM

Use Support

Class A1

Recreation - Primary contact

Fully Supported

Class BLW

Aquatic Life - Lakes and wetlands

Fully Supported

Class HH

Human Health -

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use remains assessed (monitored) as “fully supported.” The Class BLW use was assessed (monitored) as “fully supported.” The Class HH (fish consumption) use was assessed (monitored) as “fully supported” based on fish tissue sampling data. Note: A TMDL for nutrients and siltation at Easter Lake was prepared by DNR and approved by EPA in 2005.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2019-2022	22770001	Easter Lake (maximum water depth)
Iowa DNR	6	WQ	CY 2019-2019	14000293	EL-S2
Iowa DNR	6	WQ	CY 2019-2019	14000294	EL-S3
Iowa DNR	6	WQ	CY 2019-2019	14000295	EL-S4
Iowa DNR	6	FT	See Below	1009	Easter Lake on Yeader Creek	SE of Des Moines

Class A1 - Indicator Bacteria: No Data

Class A1 - pH:

Site ID	Data Source ID	# Samples / # Years	Minimum Value	Maximum Value	Mean Value	# Violations	Violations needed for impairment	Violates Significantly >10% Rule?	Assessment Type	Support Level
22770001	6	12 / 4	7.8	8.8	8.2	0	4	NO	Mon	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
14000293	6	Chlorophyll a TSI	5 / 1	41	64	52	NO	Evaluated	Full
14000294	6	Chlorophyll a TSI	5 / 1	41	65	53	NO	Evaluated	Full
14000295	6	Chlorophyll a TSI	5 / 1	37	64	51	NO	Evaluated	Full
22770001	6	Chlorophyll a TSI	17 / 4	26	71	51	NO	Mon	Full
22770001	6	Secchi TSI	12 / 4	44	73	61	NO	Mon	Full
14000293	6	Total Phosphorus TSI	5 / 1	53	89	61	NA	NA	NA
14000294	6	Total Phosphorus TSI	5 / 1	47	83	53	NA	NA	NA
14000295	6	Total Phosphorus TSI	5 / 1	47	85	53	NA	NA	NA
22770001	6	Total Phosphorus TSI	17 / 4	37	79	53	NA	NA	NA
22770001	6	Inorganic suspended solids	12 / 4	0.6	7	1.9	NA	NA	NA

DNR's assessment methodology indicates that a TSI value less than or equal to 63 is necessary to suggest de-listing of an impairment. Because the TSI value for the 2024 assessment/listing cycle is less than or equal to the delisting threshold of 63 (median TSI value for Secchi depth was 61), based on DNR's methodology, these values suggest "full support" of the Class A1 uses protecting against aesthetically objectionable conditions and the impairment (4a) for Secchi depth is suggested for removal for the 2024 assessment/listing cycle.

Class BLW - Binomial 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
22770001	6	Dissolved Oxygen	12 / 4	5.41	12	8.25	0	NA / NA	4	NO	Mon	Full
22770001	6	pH	12 / 4	7.8	8.8	8.2	0	NA / NA	4	NO	Mon	Full
22770001	6	Temperature	12 / 4	19.3	30.1	24.5	0	NA / NA	4	NO	Mon	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
22770001	6	3	0.078613746	23%	0.039958919	2%	NO	Evaluated	NA

Class BLW - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	>1 Acute / Chronic Violation	Assessment Type	Support Level
22770001	6	Ammonia	12 / 4	0.083	0.03	0.02	0 / 0	NO	Mon	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)
1009	fillet	2016	channel catfish	3	47.5	0.05	0.04	0.06
1009	tissue plug	2015	largemouth bass	10	42.1	0.089
Support Level	Full

Monitoring and Methods

Assessment Key Dates

6/5/2019

Monitoring Start

9/4/2022

Monitoring End

7/31/2015

Fish Tissue Monitoring

8/26/2016

Fish Tissue Monitoring

8/21/2015

Fish Tissue Monitoring

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

260

Fish tissue analysis

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)