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 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.

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Cycle: 2022
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: 12/27/2021 3:11:39 PM
Updated: 1/20/2022 8:16:18 AM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Turbidity

Support Level

Not Supported

Impairment Code

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

Cause Magnitude

Moderate

Status

Continuing

Source

Construction

Source Confidence

Moderate

Cycle Added

1998

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Iowa DNR-lakes

Class BLW

Aquatic Life - Lakes and wetlands

WINOFI

Sedimentation/Siltation

Support Level

Further Investigation Needed

Impairment Code

3b - Use potentially impaired based on an evaluated assessment.

Cause Magnitude

Moderate

Status

Continuing

Source

Construction

Source Confidence

Moderate

Cycle Added

1998

Impairment Rationale

Adverse impacts on plant/animal communities

Data Source

Ambient monitoring: Iowa DNR-lakes

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 “not supported” due to poor water transparency that violates Iowa’s narrative criteria protecting against aesthetically objectionable conditions. The Class BLW use was assessed (evaluated) as “WINOFI” due to siltation impacts at this lake. 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 all Section 303(d) impairments identified for the current assessment/listing cycle (siltation and turbidity) are addressed by the TMDL, this waterbody is placed in IR Category 4a (impaired; TMDL approved).

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2019-2020	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	9	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	6 / 2	7.8	8.8	8.2	0	3	NO	Evaluated	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	11 / 2	26	71	51	NO	Evaluated	Full
22770001	6	Secchi TSI	6 / 2	44	73	63	NO	Evaluated	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	11 / 2	37	79	57	NA	NA	NA
22770001	6	Inorganic suspended solids	6 / 2	0.6	4	2.4	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
22770001	6	Ammonia	6 / 2	0.0078	0.0828	0.03	NA	0 / 0	3	NO	Evaluated	Full
22770001	6	Dissolved Oxygen	6 / 2	7.6	12	9.2	0	NA / NA	3	NO	Evaluated	Full
22770001	6	pH	6 / 2	7.8	8.8	8.2	0	NA / NA	3	NO	Evaluated	Full
22770001	6	Temperature	6 / 2	19.3	30.1	24.1	0	NA / NA	3	NO	Evaluated	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)
9	fillet	2016	channel catfish	3	47.5	0.05	0.04	0.06
9	tissue plug	2015	largemouth bass	10	42.1	0.089
Support Level	Full

Monitoring and Methods

Assessment Key Dates

6/5/2019

Fixed Monitoring Start Date

9/17/2020

Fixed Monitoring End Date

7/31/2015

Fish Tissue Monitoring

8/26/2016

Fish Tissue Monitoring

8/21/2015

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

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)