2020 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.

2020
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
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Overall IR

3 - Insufficient data exist to determine whether any designated uses are met.

Trend

Unknown

Created

10/8/2020 5:42:04 AM by

Updated

10/14/2020 8:01:57 AM by

Use Support

Class A1

Presumptive Use

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

Not Assessed

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 use remains assessed as "partially supported" due to the identification of an impairment for indicator bacteria (E. coli) in the adjacent upstream segment by the Minnesota Pollution Control Agency (MPCA). All other designated uses were "not assessed".

Assessment Explanation

Presumptive Class A1:

The bacteria impairment of the primary contact recreation use of the upstream segment of the Little Cedar River was identified by MPCA in 2012. A TMDL was completed by MPCA and approved by the EPA for this impairment in 2019 (https://www.pca.state.mn.us/water/watersheds/cedar-river).

Class BWW1 - No Data

Class HH - No Data

Monitoring and Methods

Assessment Key Dates

None listed

Methods

860

Other Agencies/Organizations provided monitoring data