Prairie Rose Lake IA 05-NSH-1462

Shelby County S36T79NR38W 6 mi SE of Harlan.

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: 8/26/2020 11:46:22 AM
Updated: 10/15/2020 7:49:48 AM

Use Support

Class A1

Recreation - Primary contact

Partially Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Partially Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2012

Impairment Rationale

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

Data Source

Beach monitoring: Iowa DNR WQMA

TMDL Priority

Tier II

Algal Growth: Chlorophyll a

Support Level

Partially Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Moderate

Status

Continuing

Source

Natural: Internal Nutrient Recycling (Primarily Lakes)

Source Confidence

Moderate

Cycle Added

2004

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Iowa DNR-lakes

TMDL Priority

Tier I

Turbidity

Support Level

Partially Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

Continuing

Source

Agriculture

Source Confidence

Moderate

Cycle Added

2004

Impairment Rationale

Narrative criteria violation: aesthetically objectionable conditions

Data Source

Ambient monitoring: Iowa DNR-lakes

TMDL Priority

Tier I

Class BLW

Aquatic Life - Lakes and wetlands

Fully Supported

Class C

Drinking Water -

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 uses are assessed (monitored) as “partially supported” due to poor water transparency caused by algae blooms and non-algal turbidity. In addition, violations of the state's water quality standard for indicator bacteria also suggest an impairment at Prairie Rose Lake. The Class BLW uses are assessed (monitored) as “fully supported.” The Class C (drinking water) uses are “fully supported.” Class HH uses are assessed (monitored) as “fully supported” based on fish tissue monitoring.

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 2016-2018	21830001	Prairie Rose Beach (Prairie Rose State Park)
Iowa DNR	6	WQ	CY 2014-2018	22830002	Prairie Rose Lake	Lake Deep Point
Iowa DNR	6	WQ	CY 2016-2016	14000214	Pr Rose 1	TMDL East Sampling Point
Iowa DNR	6	WQ	CY 2016-2016	14000215	Pr Rose 2	TMDL Centeral Sampling 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
21830001	6	46 / 3	343.18	56.08	61.14	Yes	16	35%	YES	Monitored	Partial

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
22830002	6	14 / 5	9.3	8.44	8.4	2	14%	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
14000214	6	Chlorophyll a TSI	15 / 1	51	78	69	YES	Assessor Discretion	Not
14000215	6	Chlorophyll a TSI	15 / 1	52	78	70	YES	Assessor Discretion	Not
22830002	6	Chlorophyll a TSI	30 / 5	50	77	68	YES	Monitored	Not
22830002	6	Secchi TSI	15 / 5	43	73	67	YES	Monitored	Not
14000214	6	Total Phosphorus TSI	15 / 1	37	77	69	NA	NA	NA
14000215	6	Total Phosphorus TSI	15 / 1	47	75	67	NA	NA	NA
22830002	6	Total Phosphorus TSI	30 / 5	49	82	69	NA	NA	NA
22830002	6	Inorganic suspended solids	15 / 5	0.3	10.2	2.4	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
22830002	6	Ammonia	14 / 5	0.364	0.07	0.02	0 / 0	0% / 0%	NO	Monitored	Full
22830002	6	Dissolved oxygen	15 / 5	14	8.9	8.7	NA / 1	NA / 7%	NO	Monitored	Full
22830002	6	pH	14 / 5	9.3	8.44	8.4	2 / NA	14% / NA	NO	Monitored	Full
22830002	6	Temperature	15 / 5	28.6	24.3	24.2	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
22830002	6	11	85.368	99.3 %	11.234	64.2 %	NO	Evaluated	NA

Class C - Conventional Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
14000214	6	Chloride	15 / 1	13	12	12	0	0%	NO	Monitored	Full
14000215	6	Chloride	15 / 1	13	12	12	0	0%	NO	Monitored	Full
22830002	6	Chloride	15 / 1	16	12	12	0	0%	NO	Monitored	Full
14000214	6	Inorganic nitrogen (nitrate and nitrite)	15 / 1	3.1	1.16	0.72	0	0%	NO	Monitored	Full
14000215	6	Inorganic nitrogen (nitrate and nitrite)	15 / 1	3.1	1.11	0.68	0	0%	NO	Monitored	Full
22830002	6	Inorganic nitrogen (nitrate and nitrite)	30 / 5	3.1	0.76	0.05	0	0%	NO	Monitored	Full

Class HH - No Data

Note: Prairie Rose Lake was drawn down in July of 2011 and refilled in September of 2012 for restoration purposes. As a result, no samples were collected during that time. While the lake was drawn down, stabilization of the eroding shoreline and removal of 60,000 cubic yards of sediment was completed and undesirable fish species (e.g. common carp)were removed from the lake and watershed. The lake was restocked starting in April of 2013. In lake dredging started in mid-July. Approximately 185,000 CY of sediment were to be removed from Prairie Rose Lake. The project was completed in 2015. This assessment does not include post-restoration data.

Monitoring and Methods

Assessment Key Dates

6/18/2014

Fixed Monitoring Start Date

8/28/2018

Fixed Monitoring End Date

Methods

120

Surveys of fish and game biologists/other professionals

222

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

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)

420

Indicator bacteria monitoring