Little Turkey River IA 01-TRK-163

from south line of S11 T90N R3W (Delaware Co.) to confluence with unnamed tributary in the S 1/2 of S15 T90N R3W Delaware Co.

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.

Open Segment Map
View assessment methodology in new window

Cycle: 2020
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 9/25/2020 7:49:18 AM
Updated: 10/15/2020 7:25:25 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

High

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2012

Impairment Rationale

Geometric mean criterion exceeded

Data Source

TMDL monitoring: Iowa DNR

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use remains assessed as “not supported” due to violations of Iowa water quality criteria for indicator bacteria (E. coli). The Class BWW2 use remains assessed as “fully supported” based on water quality monitoring data. All other designated uses were “not assessed.”

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY2010	11280003	Little Turkey River @ Colesburg (site ltr2)

Presumptive Class A1 - Indicator Bacteria: Historical

Site ID	Data Source ID	# Samples / # Years	2010 Geometric Mean	Annual Geometric Mean Violation	# Violations	% Violations	Significantly >10% Violations	Assessment Type	Support Level
11280003	6	8 / 1	914	Yes	7	88%	Yes	Evaluated	Not

Class BWW2 - Conventional Parameters: Historical

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
11280003	6	Ammonia	9 / 1	0.36	0.08	0.05	0 / 0	0% / 0%	No	Evaluated	Full
11280003	6	Dissolved oxygen	9 / 1	12.612	10.3	10	NA / 0	NA / 0%	No	Evaluated	Full
11280003	6	pH	9 / 1	7.9	7.7	7.7	0 / NA	0% / NA	No	Evaluated	Full
11280003	6	chloride	9 / 1	26	22	24	0 / 0	0% / 0%	No	Evaluated	Full

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

3/10/2010

Non-fixed Monitoring Start Date

7/26/2010

Non-fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

220

Non-fixed station physical/chemical monitoring (conventional pollutant only)

420

Indicator bacteria monitoring