Red Rock Reservoir IA 04-LDM-1017

Marion County S19T76NR18W near Pella.

Assessment Cycle

2022

Release Status

Final

Data Collection Period

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.

Overall IR Category: 5 - Water is impaired or threatened and a TMDL is needed.
Trophic: Eutrophic
Trend: Stable

Created: 12/27/2021 2:58:38 PM
Updated: 2/17/2022 10:15:44 AM

Assessment conducted in accordance with Iowa's 2022 IR methodology

Use Support

Class A1

Recreation

Primary contact

Not Supported

Impairments

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

Continuing

Source

Natural: Waterfowl

Source Confidence

Moderate

Cycle Added

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Corps of Engineers/ISU/UI

TMDL Priority

Tier II

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

2010

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Corps of Engineers/ISU/UI

TMDL Priority

Tier II

Class BWW1

Aquatic Life

Warm Water Type 1

WINOFI

Further Investigation Needed

Support Level

Water in Need of Further Investigation (WINOFI)

Impairment Code

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

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2020

Impairment Rationale

Non Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

Class HH

Human Health

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 use of the Red Rock Reservoir was assessed (monitored) as "not supported” due to high levels of pathogens. Low water clarity also suggests an impairment at this lake due to aesthetically objectionable conditions. The Class BWW1 use was assessed (evaluated) as “WINOFI” due to fish kills that occurred in 2016 and 2020. The Class HH (fish consumption) use was assessed (monitored) as "fully supported" based on fish tissue sampling data.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
USACE	12	WQ	CY 2016-2020	27630001	Red Rock Reservoir
USACE	12	WQ	CY 2018-2020	99990029	North Overlook Beach (Red Rock Reservoir)
USACE	12	WQ	CY 2018-2020	99990032	Whitebreast Beach (Red Rock Reservoir)
Iowa DNR	6	WQ	CY 2016-2016	22630001	Red Rock Reservoir
Iowa DNR	6	FT	See Below	324	Red Rock Reservoir	W of Pella
USACE	12	FT	See Below	NA	Red Rock Reservoir

Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2018/ 2019/2020)

2018 Geometric Mean

2019 Geometric Mean

2020 Geometric Mean

Violates Annual Geometric Mean?

# 2018 SSM violations / SSM Violations needed for impairment

# 2019 SSM violations / SSM Violations needed for impairment

# 2020 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

27630001

10/10/7

0 / 3

Monitored

Full

99990029

17/22/20

115

5 / 4

11 / 5

9 / 5

YES

Monitored

Not

99990032

14/14/19

4 / 4

2 / 4

5 / 5

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
27630001	12	71 / 5	6.99	8.89	8.22	0	11	NO	Monitored	Full
22630001	6	3 / 1	7.7	8.1	7.9	0	2	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
27630001	12	Chlorophyll a TSI	48 / 5	46	82	64	NO	Monitored	Full
27630001	12	Secchi TSI	69 / 5	52	81	68	YES	Monitored	Not
27630001	12	Total Phosphorus TSI	71 / 5	53	96	77	NA	NA	NA
22630001	6	Chlorophyll a TSI	3 / 1	48	53	52	NO	Evaluated	Full
22630001	6	Secchi TSI	3 / 1	63	77	67	YES	Evaluated	Not
22630001	6	Total Phosphorus TSI	3 / 1	72	83	79	NA	NA	NA
22630001	6	Inorganic suspended solids	3 / 1	6.3	20.2	9.6	NA	NA	NA

Class BWW1 - 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
27630001	12	Ammonia	71 / 5	0.02	0.84	0.08	NA	0 / 0	11	NO	Monitored	Full
27630001	12	Dissolved Oxygen	71 / 5	5.74	20.22	10.01	0	NA / NA	11	NO	Monitored	Full
27630001	12	pH	71 / 5	6.99	8.89	8.22	0	NA / NA	11	NO	Monitored	Full
27630001	12	Temperature	71 / 5	4.5	31.7	21	0	NA / NA	11	NO	Monitored	Full
99990029	12	Temperature	44 / 2	16.6	32	26.6	0	NA / NA	8	NO	Monitored	Full
99990032	12	Temperature	35 / 2	21.2	32.5	26.4	1	NA / NA	7	NO	Monitored	Full
22630001	6	Ammonia	3 / 1	0.0003	0.158	0.06	NA	0 / 0	2	NO	Evaluated	Full
22630001	6	Dissolved Oxygen	3 / 1	4.4	6.3	5.6	1	NA / NA	2	NO	Evaluated	Full
22630001	6	pH	3 / 1	7.7	8.1	7.9	0	NA / NA	2	NO	Evaluated	Full
22630001	6	Temperature	3 / 1	21.6	26.9	24.8	0	NA / NA	2	NO	Evaluated	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
22630001	6	3	0.46	31.0%	0.30	12.6%	NO	Evaluated	NA

Class BWW1 - Fish Kill Assessment:

The Class BWW1 aquatic life use assessment based on the2016 and 2020fish kill placed this segment in Category 3b. This assessment was “evaluated” because: (1) the cause of the fish kill(s) was not identified or (2) the fish kill(s) was attributed to a non-pollutant cause (e.g., winterkill). Segments assessed using “evaluated” assessments are placed in Category 3b and are added to the state list of Waters In Need Of Further Investigation (WINOFI). If no additional fish kills are reported in this segment for a 10-year period (2030), the Category will be changed from 3b to 3a (not assessed).

Details about the 2016 fish kill can be found here: https://programs.iowadnr.gov/fishkill/Events/915

Details about the 2020 fish kill can be found here:https://programs.iowadnr.gov/fishkill/Events/1002

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)
324	tissue plug	2020	flathead catfish	2	46.8	0.084
324	tissue plug	2019	flathead catfish	13	45.6	0.09
Support Level	Full

Class HH - Historic USACE Fish Tissue Sampling:

The fish consumption use was assessed (monitored) as “fully supported” based on results of ACOE/ISU fish contaminant monitoring at Red Rock Lake in 2012, 2013, and 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: 0.003 ppm; 2013: 0.003 ppm; 2014: 0.130 ppm. None of these levels approach the advisory trigger level of 0.6 ppm 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 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 the issuance of a consumption advisory for this waterbody.

Monitoring and Methods

Assessment Key Dates

3/7/2016

Fixed Monitoring Start Date

12/7/2020

Fixed Monitoring End Date

6/18/2014

Fish Tissue Monitoring

8/1/2013

Fish Tissue Monitoring

5/17/2012

Fish Tissue Monitoring

7/1/2019

Fish Tissue Monitoring

7/1/2020

Fish Tissue Monitoring

Methods

120

Surveys of fish and game biologists/other professionals

140

Incidence of spills and/or fish kills

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