Saylorville Reservoir IA 04-UDM-1213

Polk County Saylorville Dam to Polk-Dallas county line.

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: 5 - Water is impaired or threatened and a TMDL is needed.
Trophic: Eutrophic
Trend: Stable
Created: 8/14/2020 1:45:59 PM
Updated: 10/14/2020 1:17:05 PM

Use Support

Class A1

Recreation - Primary contact

Not Supported

Turbidity: Secchi Disk Transparency

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

Status

Continuing

Source

Other: Sediment Resuspension

Source Confidence

Moderate

Cycle Added

2016

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Corps of Engineers/ISU/UI

TMDL Priority

Tier II

Aesthetics: Aesthetically Objectionable Conditions

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

2020

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Corps of Engineers/Iowa DNR-Lakes

TMDL Priority

Tier II

Class BWW1

Aquatic Life - Warm Water Type 1

Fully Supported

Class HH

Human Health -

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use of Saylorville Reservoir is assessed (monitored) as "not supported” due to poor water transparency caused by non-algal turbidity and due to high levels of indicator bacteria. The Class BWW1 use is assessed (monitored) as "fully supported." Class HH use remains assessed (monitored) as "fully supported" based on ACOE-sponsored annual fish contaminant monitoring from 2012-14.

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
USACE	12	WQ	CY 2014-2018	27770001	Saylorvill Reservoir - Surface	Lake Deep point
USACE	12	WQ	CY 2016-2018	99990030	Oak Grove Beach Saylorville
USACE	12	WQ	CY 2016-2018	99990031	Sandpiper Beach Saylorville
USACE		FT	See Below		Saylorvill Reservoir
Iowa DNR	6	WQ	CY 2014-2016	22770005	Saylorville Reservoir	Lake Deep point

Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples / # Years	2016 Geometric Mean	2017 Geometric Mean	2018 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
27770001	12	54 / 4	1.88	NA	NA	No	0	0%	NO	Monitored	Full
99990030	12	35 / 3	12.5	18.95	410.6	Yes	3	9%	YES	Monitored	Partial
99990031	12	44 / 3	17.04	15.05	26.65	No	3	7%	NO	Monitored	Full

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
22770005	6	9 / 3	8.51	8.06	8	0	0%	NO	Evaluated	Full
27770001	12	82 / 5	8.68	8.15	8.18	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
22770005	6	Chlorophyll a TSI	9 / 3	41	67	59	NO	Monitored	Full
27770001	12	Chlorophyll a TSI	51 / 5	31	77	61	NO	Monitored	Full
22770005	6	Secchi TSI	9 / 3	54	73	67	YES	Monitored	Not
27770001	12	Secchi TSI	82 / 5	41	79	67	YES	Monitored	Not
22770005	6	Total Phosphorus TSI	9 / 3	63	82	72	NA	NA	NA
27770001	12	Total Phosphorus TSI	82 / 5	49	108	75	NA	NA	NA
22770005	6	Inorganic suspended solids	9 / 3	1.05	18.6	8.6	NA	NA	NA

Class BWW1 - 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
22770005	6	Ammonia	9 / 3	0.306	0.08	0.05	0 / 0	0% / 0%	NO	Evaluated	Full
27770001	12	Ammonia	82 / 5	1.12	0.12	0.06	0 / 0	0% / 0%	NO	Monitored	Full
22770005	6	Dissolved oxygen	9 / 3	16.42	9.07	6.75	NA / 0	NA / 0%	NO	Evaluated	Full
27770001	12	Dissolved oxygen	82 / 5	19.11	9.37	9.14	NA / 2	NA / 2%	NO	Monitored	Full
22770005	6	pH	9 / 3	8.51	8.06	8	0 / NA	0% / NA	NO	Evaluated	Full
27770001	12	pH	82 / 5	8.68	8.15	8.18	0 / NA	0% / NA	NO	Monitored	Full
22770005	6	Temperature	9 / 3	25.81	22.02	22.49	0 / 0	0% / 0%	NO	Evaluated	Full
27770001	12	Temperature	82 / 5	29.2	19.6	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
22770005	6	9	26.917	92.3 %	8.169	50 %	NO	Evaluated	NA

Class HH - Fish Tissue Sampling:

Fish consumption uses were assessed (monitored) as “fully supported” based on results of ACOE/ISU fish contaminant monitoring at Saylorville Reservoir in 2012-2014. The composite samples of whole-fish common carp had low levels of contaminants. Levels of total chlordane in the composite samples were as follows: 2012: 0.002ppm; 2013: 0.004ppm; 2014: 0.130ppm. None of these levels approach the advisory trigger level of 0.6ppm for chlordane. In 2012, 2013, and 2014, composite samples of whole-fish carp were analyzed for total PCBs and Aroclors 1248, 1254, and 1260. Total PCBs in composite samples of whole-fish carp were 0.002 ppm (2012) and 0.002 (2013).PCB Aroclors 1248, 1254, and 1260 were all 0.0002 ppm(2014).The levels of PCBs seen in fish tissue samples from ISU/ACOE in Saylorville Reservoir are well below the one meal per week advisory trigger of 0.20 ppm for total PCBs. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses. The levels of contaminants do not exceed any of the advisory trigger levels, thus indicating no justification for issuance of a consumption advisory for this waterbody.

Monitoring and Methods

Assessment Key Dates

4/7/2014

Fixed Monitoring Start Date

11/5/2018

Fixed Monitoring End Date

5/15/2012

Fish Tissue Monitoring

7/31/2013

Fish Tissue Monitoring

5/28/2014

Fish Tissue Monitoring

Methods

120

Surveys of fish and game biologists/other professionals

222

Non-fixed-station monitoring (conventional during key seasons and flows)

230

Fixed station physical/chemical (conventional plus toxic pollutants)

260

Fish tissue analysis

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)

420

Indicator bacteria monitoring