DRAFT 2026 assessment for Fourmile Creek

Fourmile Creek IA 04-LDM-1112

mouth (S16 T78N R23W Polk Co.) to county road bridge (First Street Ankeny) in S18 T80N R23W PolkCo.

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

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

Trend

Stable

Current Phase

Public Comment

Created

10/27/2025 3:09:04 PM by

Updated

1/13/2026 11:13:57 AM by

Use Support

Class A1

Recreation - Primary contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class BWW2 use was assessed as "fully supported" based on biological sampling data and 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	BIO	See Below	1242	Fourmile Creek	Berwick
PCCB	29	WQ	CY 2022-2024	99990217	Four Mile Creek
PCCB	29	WQ	CY 2022-2024	99990224	Four Mile Creek
PCCB	29	WQ	CY 2022-2024	99990292	Four Mile Creek
PCCB	29	WQ	CY 2022-2024	99990234	Four Mile Creek
PCCB	29	WQ	CY 2022-2024	99990241	Four Mile Creek
PCCB	29	WQ	CY 2022-2024	99990242	Four Mile Creek
PCCB	29	WQ	CY 2022-2024	99990257	Four Mile Creek

Class A1 - No Data

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
99990217	29	Chloride	6 / 2	11.39	74.92	48.77	NA	0 / 0	3	NO	EVALUATED	FULL
99990224	29	Chloride	5 / 3	44.19	83.48	59.7	NA	0 / 0	2	NO	EVALUATED	FULL
99990292	29	Chloride	6 / 3	15	70.8	44	NA	0 / 0	3	NO	EVALUATED	FULL
99990217	29	Sulfate	6 / 2	11.07	47.43	31.09	0	NA / NA	3	NO	EVALUATED	FULL
99990224	29	Sulfate	5 / 3	27.89	51.77	37.46	0	NA / NA	2	NO	EVALUATED	FULL
99990292	29	Sulfate	6 / 3	11.72	50.94	30.56	0	NA / NA	3	NO	EVALUATED	FULL
99990217	29	Temperature	52 / 3	0	31.11	14.44	0	NA / NA	9	NO	MONITORED	FULL
99990224	29	Temperature	62 / 3	0	31.67	15.57	0	NA / NA	10	NO	MONITORED	FULL
99990234	29	Temperature	48 / 3	-1.11	29.44	14.01	0	NA / NA	9	NO	MONITORED	FULL
99990241	29	Temperature	41 / 3	-1.11	26.67	13.33	0	NA / NA	8	NO	MONITORED	FULL
99990242	29	Temperature	46 / 3	-1.11	27.78	13.35	0	NA / NA	8	NO	MONITORED	FULL
99990257	29	Temperature	59 / 3	0	26.67	14.92	0	NA / NA	10	NO	MONITORED	FULL
99990292	29	Temperature	5 / 3	15	22.78	19	0	NA / NA	2	NO	EVALUATED	FULL

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47b BMIBI BIT	BMIBI Pass/Fail
1242	9/6/19	70.5	47b	MS	Surber	54	Fair	62	Pass*

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47b FIBI BIT	FIBI Pass/Fail
1242	9/6/19	70.5	47b	MS	Yes	58	Good	53	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Pass (1/1)	Full		*The BMIBI score passed after using the 8 point UAV applied to single samples.
Fish	Evaluated	Pass (1/1)	Full	1
Overall	Evaluated	Pass	Full		Assessment was evaluated because it was based on a single sample.

Monitoring and Methods

Assessment Key Dates

9/6/2019

Biological Monitoring

1/7/2022

Monitoring Start

12/19/2024

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

200

Physical/Chemical Monitoring

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

860

Other Agencies/Organizations provided monitoring data