Don Williams Lake IA 04-UDM-1249

Boone County S5T84NR27W 5 mi. N of Ogden.

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.

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Cycle: 2020
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: 8/19/2020 10:07:08 AM
Updated: 10/14/2020 1:25:00 PM

Use Support

Class A1

Recreation - Primary contact

Partially Supported

Algal Growth: Chlorophyll a

Support Level

Partially Supported

Impairment Code

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

Cause Magnitude

Slight

Status

New

Source

Agriculture

Source Confidence

Moderate

Cycle Added

2020

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Iowa DNR-lakes

Class BLW

Aquatic Life - Lakes and wetlands

Partially Supported

Sedimentation/Siltation

Support Level

Partially Supported

Impairment Code

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

Cause Magnitude

Moderate

Status

Continuing

Source

Agriculture

Source Confidence

Moderate

Cycle Added

2004

Impairment Rationale

Adverse impacts on plant/animal communities

Data Source

Biological monitoring: Iowa DNR Fisheries

Class HH

Human Health -

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

Cycle Added	Class	Cause	Data Source	Rationale
2018	Class A1	Bacteria: Indicator Bacteria- E. coli	Beach monitoring: Iowa DNR city/county	Assessment Error

Documentation

Assessment Summary

The Class A1 use is assessed (monitored) as “not supported” due to aesthetically objectionable conditions caused by algae blooms. The Class BLW use is assessed (evaluated) as “partially supported” due to siltation impacts, especially in the upper portions of the lake. Class HH use is assessed (monitored) as "fully supported" based on the results of fish tissue monitoring. Note: A TMDL for organic enrichment and siltation at Don Williams Lake was prepared by DNR and approved by EPA in 2005. Because all Section 303(d) impairments identified for the current assessment/listing cycle are addressed by the TMDL, this waterbody remains in IR Category 4a.

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	21080001	Don Williams Park Beach
Iowa DNR	6	WQ	CY 2014-2018	22080004	Don Williams Lake (maximum water depth)
Iowa DNR		FT	See Below	96	Don Williams Lake

Class A1 - Indicator Bacteria: Historical 2018 Assessment cycle

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
21080001	6	45 / 3	25	46	9	No	4	9%	NO	Monitored	Full

Due to an assessment error the 2018 bacteria impairment is being removed based on methodology. The total number of violations should have been interpreted as not exceeding the Significantly >10% Violations rule.

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
22080004	6	15 / 5	8.5	8	8	0	0%	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
22080004	6	Chlorophyll a TSI	15 / 5	43	80	64	NO	Monitored	Full
22080004	6	Secchi TSI	15 / 5	51	83	65	YES	Monitored	Not
22080004	6	Total Phosphorus TSI	15 / 5	33	87	64	NA	NA	NA
22080004	6	Inorganic suspended solids	15 / 5	0.3	15.4	5	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
22080004	6	Ammonia	15 / 5	0.39275	0.08	0.04	0 / 0	0% / 0%	NO	Monitored	Full
22080004	6	Dissolved oxygen	15 / 5	15.9	10.4	11	NA / 1	NA / 7%	NO	Monitored	Full
22080004	6	pH	15 / 5	8.5	8	8	0 / NA	0% / NA	NO	Monitored	Full
22080004	6	Temperature	15 / 5	25.7	21.3	22.2	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
22080004	6	10	45.691	88.5 %	0.535	3.85 %	NO	Evaluated	NA

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

7/20/10

largemouth bass

fillet

0.0978

Evaluated

Full

7/23/10

channel catfish

fillet

<0.03

<0.09

0.0443

Evaluated

Full

Monitoring and Methods

Assessment Key Dates

5/19/2014

Fixed Monitoring Start Date

8/14/2018

Fixed Monitoring End Date

7/23/2010

Fish Tissue Monitoring

3/10/2005

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)

420

Indicator bacteria monitoring