DRAFT 2026 assessment for Middle Fork Grand River

Middle Fork Grand River IA 05-GRA-1378

IA/MO line to trib S13T68NR30W Ringgold

This is a DRAFT assessment

Draft assessments may change without notice

2026
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 2022 - 2024
Stream/River Water Quality Data	CY 2022 - 2024
Lake Water Quality Data	CY 2020 - 2024
Biological Sampling Data	CY 2020 - 2024*
Fish Kill Data	CY 2020 - 2024
Fish Tissue Sampling Data	CY 2020 - 2024
Continuous Dissolved Oxygen Sampling Data	CY 2020 - 2024
*Biological sites sampled in both 2019 and 2023 were also assessed.

Open Segment Map
View 2026 assessment summary page

Overall IR

5 - Water is impaired or threatened and a TMDL is needed.

Trend

Stable

Current Phase

Public Comment

Created

10/27/2025 3:09:59 PM by

Updated

11/25/2025 11:07:47 AM by

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

Moderate

303(d) Listing Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2014

Impairment Rationale

Geometric mean criterion exceeded

Data Source

TMDL monitoring: Iowa DNR

TMDL Priority

Tier III

Class BWW2

Aquatic Life - Warm Water Type 2

Not Supported

Biological: low fish & invert IBIs- cause unknown

Support Level

Not Supported

Impairment Code

5b-t - Biological - tentative

Cause Magnitude

Moderate

303(d) Listing Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2006

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

TMDL Priority

Tier IV

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 use was assessed as “not supported” due to violations of state water quality criteria for indicator bacteria (E. coli). The Class BWW2 use remains assessed as “not supported” based on biological sampling data.

Assessment Explanation

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	WQ	CY 2024	14000043	Middle Fork Grand River - Mt Ayr (MFGR3)
Iowa DNR	6	BIO & WQ	See Below	397	Middle Fork Grand River	Mt. Ayr (REMAP #114)

Presumptive Class A1 - Indicator Bacteria:

Site ID	Data Source ID	# Samples per Year (2024)	2024 Geometric Mean	Violates Annual Geometric Mean?	# 2024 SSM violations / SSM Violations needed for impairment	Violates Annual SSM Significantly >10% Rule?	Assessment Type	Support Level
14000043	6	15	2237	YES	14 / 4	YES	MONITORED	NOT

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
14000043	6	13 / 1	7.75	8.32	8	0	4	NO	MONITORED	FULL

Class BWW2 - Binomial 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
14000043	6	Dissolved Oxygen	13 / 1	5.95	12.59	9.07	0	NA / NA	4	NO	MONITORED	FULL
14000043	6	pH	13 / 1	7.75	8.32	8	0	NA / NA	4	NO	MONITORED	FULL
14000043	6	Temperature	12 / 1	11.186	25.738	19.044	0	NA / NA	4	NO	MONITORED	FULL

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	BM Sample Gear	BMIBI score	BMIBI Class	40a BMIBI BIT	BMIBI Pass/Fail
397	7/8/21	8.7	40a	MO/WW	ArtSub	27	Poor	41	Fail

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/Thermal	Riffle Stream?	FIBI score	FIBI Class	40a FIBI BIT	FIBI Pass/Fail
397	7/8/21	8.7	40a	MO/WW	NA	19	Poor	33	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/1)	Not		Assessment was evaluated because it was based on a single sample,
Fish	Evaluated	Fail (0/1)	Not		the drainage area of the sample was smaller than the calibrated range,
Overall	Evaluated	Fail	Not	5bt	and the sample was collected outside of the index period (7/15-10-15).

Class BWW2- Continuous DO Monitoring:

Site ID	Data Source ID	# Days Monitoring (2021)	DO Criteria Type	# 2021 violations / Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	1/4	No
397	6	17	16 hr	0/4	No	Evaluated	Full

Monitoring and Methods

Assessment Key Dates

7/8/2021

Biological Monitoring

6/22/2021

Monitoring Start

7/8/2021

Monitoring End

4/9/2024

Monitoring Start

11/12/2024

Monitoring End

Methods

200

Physical/Chemical Monitoring

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring