Retired Segment: Iowa River

Segment Parameters

Segment ID

3102

Segment Name

Iowa River

Location Desc

from confluence with Deer Creek at Tama (S34 T83N R15W Tama County) to confluence with small unnamed tributary near boundary of Meskwaki settlement (T83N R15W Sec32 SE NW Tama County)

Uses

A1,BWW1,HH

WBType

River

Size

2.7

CreateDate

9/3/2021 1:13:32 PM

Basins

02-IOW

Retirement

Retired Date

8/27/2026 12:58:26 PM

Reason

For the 2024 cycle this segment was merged with segment 639. It was created from the remains of the removed Mesqwaki segment for the Iowa River, and is inaccessible for assessment purposes.

Segment Memos

9/3/2021

August 2021 segment review. This segment was previously part of SegID 640. To avoid Meskwaki settlement boundaries, segment 640 was split. This is the lower portion of that segment. It retains the original start point (Deer Creek) and now ends at a small ditch/tributary just downstream of the Meskwaki boundary. It retains the same use designations as segment 640 (A1, BWW1, HH).

Assessments

2026 Assessment Cycle

Overall IR Category: 3
Trend: Unknown
Last Updated: 2/4/2026 9:05:39 AM

Use Support

Not Assessed

BWW1

Not Assessed

Summary

Insufficient water quality information available to assess use support.

Narrative

2022 Assessment Cycle

Overall IR Category: 2
Trend: Unknown
Last Updated: 1/18/2022 12:49:10 PM

Use Support

GenUse

Not Assessed

WINOFI

Impairment Code

Cause

Bacteria: Indicator Bacteria- E. coli

Status

New

Magnitude

Moderate

Source

Unknown: Source Unknown

Confidence

N/A

Cycle Listed

2022

Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: adjacent state

TMDL Priority

BWW1

Fully Supported

Key Dates

4/24/2018

Non-fixed Monitoring Start Date

9/17/2020

Non-fixed Monitoring End Date

Methods

Non-fixed station physical/chemical (conventional + toxicants)

Indicator bacteria monitoring

Summary

The Class A1 use was assessed as “WINOFI” based on levels of indicator bacteria (E. coli) that exceeded state water quality criteria. The Class BWW1 and Class HH (fish consumption) uses were assessed as "fully supported" based on water quality monitoring data.

Narrative

Data Sources:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
MESK	25	WQ	CY 2018-2020	99990097	Iowa River

Class A1 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2018/ 2019/2020)

2018 Geometric Mean

2019 Geometric Mean

2020 Geometric Mean

Violates Annual Geometric Mean?

# 2018 SSM violations / SSM Violations needed for impairment

# 2019 SSM violations / SSM Violations needed for impairment

# 2020 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

99990097

4/5/4

333

584

196

YES

2 / NA

4 / NA

1 / NA

Evaluated

WINOFI

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
99990097	25	13 / 3	8.04	8.38	8.22	0	4	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
99990097	25	Dissolved Oxygen	13 / 3	7.43	11.43	9.05	0	NA / NA	4	NO	Monitored	Full
99990097	25	pH	13 / 3	8.04	8.38	8.22	0	NA / NA	4	NO	Monitored	Full
99990097	25	Temperature	13 / 3	11.2	25.4	17.4	0	NA / NA	4	NO	Monitored	Full

Class BWW1 - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	# Acute / Chronic Violations	>1 Acute / Chronic Violation	Assessment Type	Support Level
99990097	25	Aluminum	11 / 3	7.6	2.4	1.7	0 / 0	NO	Monitored	Full
99990097	25	Copper	6 / 2	0.01	0.01	0.005	0 / 0	NO	Evaluated	Full

Class HH-F - Toxic Parameters:

Site ID	Data Source ID	Parameter Name	# Samples / # Years	Maximum Value	Mean Value	Median Value	Number of Non - Detects	Mean Value > Criterion or MCL	Assessment Type	Support Level
99990097	25	Copper	6 / 2	0.01	0.01	0.005	5	NO	Evaluated	Full