2022 assessment for Little Cedar River

Little Cedar River IA 02-CED-579

from dam of impoundment at Stacyville (SE 1/4 S31 T100N R16W Mitchell Co.) to the Iowa/Minnesota state line at N line S9 T100N R16W Mitchell Co.

2022
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 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.

Open Segment Map
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Overall IR

2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.

Trend

Unknown

Created

12/30/2021 8:45:21 AM by

Updated

3/30/2022 10:01:21 AM by

Use Support

Class A1

Recreation - Primary contact

WINOFI

Bacteria: Indicator Bacteria- E. coli

Support Level

Further Investigation Needed

Impairment Code

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

Cause Magnitude

Moderate

303(d) Listing Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2016

Impairment Rationale

Potential Impairment

Data Source

Ambient monitoring: adjacent state

Class BWW1

Aquatic Life - Warm Water Type 1

Fully Supported

Class HH

Human Health -

Not Assessed

General Use

General Use water -

Not Assessed

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 (primary contact recreation) uses are assessed as "not supported" due to identification of an impairment for indicator bacteria (E. coli) in the adjacent upstream segment by the Minnesota Pollution Control Agency (MPCA) in 2012. The Class BWW1 use was 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
MNPCA	15	WQ	CY 2018-2020	99990104	Little Cedar River

Presumptive Class A1:

Presumptive 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
99990104	15	28 / 3	6.94	8.38	7.9	0	6	NO	Monitored	Full

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
99990104	15	Dissolved Oxygen	28 / 3	6.55	13.93	9.48	0	NA / NA	6	NO	Monitored	Full
99990104	15	pH	28 / 3	6.94	8.38	7.9	0	NA / NA	6	NO	Monitored	Full
99990104	15	Temperature	28 / 3	6.38	24	18.11	0	NA / NA	6	NO	Monitored	Full

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

4/26/2018

Non-fixed Monitoring Start Date

9/9/2020

Non-fixed Monitoring End Date

Methods

220

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

420

Indicator bacteria monitoring

860

Other Agencies/Organizations provided monitoring data