Easter Lake IA 04-LDM-1024

Polk County S19T78R23W SE edge of Des Moines.

This is a DRAFT assessment

Draft assessments may change without notice

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 2022 - 2024
Stream/River Water Quality Data	CY 2022 - 2024
Lake Water Quality Data	CY 2020 - 2024
Biological Sampling Data	CY 2020 - 2024*
Fish Kill Data	CY 2020 - 2024
Fish Tissue Sampling Data	CY 2020 - 2024
Continuous Dissolved Oxygen Sampling Data	CY 2020 - 2024
*Biological sites sampled in both 2019 and 2023 were also assessed.

Open Segment Map
View 2026 assessment summary page

Cycle: 2026
Current Phase: Public Comment
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trophic: Eutrophic
Trend: Improving
Trend Comment: Chlorophyll a and Secchi TSI's continue decline after restoration project.
Created: 10/27/2025 3:09:48 PM
Updated: 12/3/2025 10:40:27 AM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

Status

New

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2026

Impairment Rationale

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

Data Source

Beach monitoring: City/County

TMDL Priority

Tier II

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 was assessed as "not supported" due to high levels of indicator bacteria. 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. Because not all Section 303(d) impairments identified for the current assessment/listing cycle (Indicator Bacteria) are addressed by the TMDL, this waterbody was placed in IR Category 5a (impaired; TMDL needed).

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2020-2023	14000293	EL-S2
Iowa DNR	6	WQ	CY 2020-2023	14000294	EL-S3
Iowa DNR	6	WQ	CY 2020-2023	14000295	EL-S4
Iowa DNR	6	WQ	CY 2020-2024	22770001	Easter Lake (maximum water depth)	Lake Deep Point
Polk County	29	WQ	CY 2022-2024	21770002	Easter Lake Park Beach

Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2022/ 2023/2024)

2022 Geometric Mean

2023 Geometric Mean

2024 Geometric Mean

Violates Annual Geometric Mean?

# 2022 SSM violations / SSM Violations needed for impairment

# 2023 SSM violations / SSM Violations needed for impairment

# 2024 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

21770002

14/0/18

165

103

YES

6 / 4

YES

MONITORED

NOT

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
14000293	6	16 / 3	7.41	8.91	8.21	0	4	NA	NA	NA
14000294	6	16 / 3	7.41	8.84	8.14	0	4	NA	NA	NA
14000295	6	16 / 3	7.57	8.82	8.21	0	4	NA	NA	NA
22770001	6	31 / 5	7.2	8.8	8.2	0	6	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
14000293	6	Chlorophyll a TSI	18 / 4	41	65	60	NA	NA	NA
14000293	6	Secchi TSI	18 / 4	43	82	64	NA	NA	NA
14000293	6	Total Phosphorus TSI	18 / 4	53	81	63	NA	NA	NA
14000294	6	Chlorophyll a TSI	18 / 4	37	68	60	NA	NA	NA
14000294	6	Secchi TSI	18 / 4	46	69	62	NA	NA	NA
14000294	6	Total Phosphorus TSI	18 / 4	53	83	61	NA	NA	NA
14000295	6	Chlorophyll a TSI	18 / 4	37	69	60	NA	NA	NA
14000295	6	Secchi TSI	18 / 4	45	69	65	NA	NA	NA
14000295	6	Total Phosphorus TSI	18 / 4	47	71	59	NA	NA	NA
22770001	6	Chlorophyll a TSI	33 / 5	41	71	61	NO	MONITORED	FULL
22770001	6	Secchi TSI	33 / 5	43	73	62	NO	MONITORED	FULL
22770001	6	Total Phosphorus TSI	33 / 5	37	73	57	NA	NA	NA
22770001	6	Fixed suspended solids	15 / 5	0.7	7	3	NA	NA	NA

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
14000293	6	Dissolved Oxygen	16 / 3	5.06	11.63	8.97	0	NA / NA	4	NA	NA	NA
14000293	6	pH	16 / 3	7.41	8.91	8.21	0	NA / NA	4	NA	NA	NA
14000293	6	Temperature	16 / 3	9.11	27.69	19.88	0	NA / NA	4	NA	NA	NA
14000294	6	Dissolved Oxygen	16 / 3	4.35	13.15	8.72	3	NA / NA	4	NA	NA	NA
14000294	6	pH	16 / 3	7.41	8.84	8.14	0	NA / NA	4	NA	NA	NA
14000294	6	Temperature	16 / 3	9.4	28.1	20.1	0	NA / NA	4	NA	NA	NA
14000295	6	Dissolved Oxygen	16 / 3	4.03	12.52	9.04	1	NA / NA	4	NA	NA	NA
14000295	6	pH	16 / 3	7.57	8.82	8.21	0	NA / NA	4	NA	NA	NA
14000295	6	Temperature	16 / 3	8.32	27.99	19.94	0	NA / NA	4	NA	NA	NA
22770001	6	Dissolved Oxygen	31 / 5	5.17	12	8.42	0	NA / NA	6	NO	MONITORED	FULL
22770001	6	pH	31 / 5	7.2	8.8	8.2	0	NA / NA	6	NO	MONITORED	FULL
22770001	6	Temperature	31 / 5	8.56	28.66	22.25	0	NA / NA	6	NO	MONITORED	FULL

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	15 / 5	0.083	0.03	0.02	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 Concentration = 75th Percentile	Assessment Type	Support Level
22770001	6	5	0.7231	53.81%	0.0786	23.15%	NO	EVALUATED	NA

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

4/23/2020

Monitoring Start

9/18/2024

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)