Beaver Creek IA 02-CED-555

mouth (S34 T90N R14W Black Hawk Co.) to confluence with South Beaver Cr. in S25 T90R R17W Butler Co.

This is a DRAFT assessment

Draft assessments may change without notice

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

Cycle: 2026
Current Phase: Public Comment
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Stable
Created: 10/27/2025 3:09:41 PM
Updated: 11/20/2025 9:49:59 AM

Use Support

Class A2

Recreation - Secondary contact

Fully Supported

Class A3

Recreation - Children's contact

Not Supported

Bacteria: Indicator Bacteria- E. coli

Support Level

Not Supported

Impairment Code

5a - Pollutant-caused impairment. TMDL needed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2008

Impairment Rationale

Geometric mean criterion exceeded

Data Source

Ambient monitoring: Iowa DNR-rivers

TMDL Priority

Tier III

Class BWW1

Aquatic Life - Warm Water Type 1

Fully Supported

Class HH

Human Health -

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A2 use was assessed as "fully supported" based on water quality monitoring data that shows support for indicator bacteria (E. coli). The Class A3 use was assessed as "not supported" due to levels of indicator bacteria (E. coli) that violated state water quality criteria. The Class BWW1 use was assessed as “fully supported” based on water quality monitoring data and on biological sampling data. The Class HH use was assessed as "fully supported" based on water quality monitoring 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 2022-2024	10070001	Beaver Creek near Cedar Falls
CRWQ	23	WQ	CY 2022-2024	99990069	Beaver Creek
CRWQ	23	WQ	CY 2022-2024	99990074	Beaver Creek
CRWQ	23	WQ	CY 2022-2024	99990075	Beaver Creek
Iowa DNR	6	BIO	See Below	373	Beaver Creek	New Hartford – REMAP #76
Iowa DNR	6	BIO	See Below	947	Beaver Creek	Cedar Falls

Class A3 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2022/ 2023/2024)

2022 Geometric Mean

2023 Geometric Mean

2024 Geometric Mean

Violates Annual Geometric Mean?

# 2022 SSM violations / SSM Violations needed for impairment

# 2023 SSM violations / SSM Violations needed for impairment

# 2024 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10070001

8/8/8

424

246

230

YES

6 / 3

5 / 3

4 / 3

YES

MONITORED

NOT

99990069

5/5/5

123

221

YES

3 / NA

1 / NA

3 / NA

YES

Evaluated

NOT

99990074

5/5/5

197

163

213

YES

3 / NA

2 / NA

YES

Evaluated

NOT

99990075

5/5/5

174

204

271

YES

2 / NA

3 / NA

YES

Evaluated

NOT

Class A2 - Indicator Bacteria:

Site ID

Data Source ID

# Samples per Year (2022/ 2023/2024)

2022 Geometric Mean

2023 Geometric Mean

2024 Geometric Mean

Violates Annual Geometric Mean?

# 2022 SSM violations / SSM Violations needed for impairment

# 2023 SSM violations / SSM Violations needed for impairment

# 2024 SSM violations / SSM Violations needed for impairment

Violates Annual SSM Significantly >10% Rule?

Assessment Type

Support Level

10070001

8/8/8

424

246

230

0 / 3

MONITORED

FULL

99990069

5/5/5

123

221

0 / NA

Evaluated

FULL

99990074

5/5/5

197

163

213

0 / NA

Evaluated

FULL

99990075

5/5/5

174

204

271

0 / NA

Evaluated

FULL

Class A2 & A3 – 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
10070001	6	35 / 3	7.6	8.7	8.1	0	7	NO	MONITORED	FULL
99990069	23	14 / 3	7.73	8.46	8.13	0	4	NO	MONITORED	FULL
99990074	23	14 / 3	7.73	8.45	8.1	0	4	NO	MONITORED	FULL
99990075	23	14 / 3	7.78	8.47	8.09	0	4	NO	MONITORED	FULL

Class BWW1 - 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
10070001	6	Chloride	36 / 3	16	35	23	NA	0 / 0	7	NO	MONITORED	FULL
99990069	23	Chloride	15 / 3	17.2	32.5	22.6	NA	0 / 0	4	NO	MONITORED	FULL
99990074	23	Chloride	15 / 3	17	33.9	23.4	NA	0 / 0	4	NO	MONITORED	FULL
99990075	23	Chloride	15 / 3	17	33.9	23.8	NA	0 / 0	4	NO	MONITORED	FULL
10070001	6	Dissolved Oxygen	35 / 3	7.6	13.8	10.3	0	NA / NA	7	NO	MONITORED	FULL
99990069	23	Dissolved Oxygen	15 / 3	4.4	12.8	8.3	2	NA / NA	4	NO	MONITORED	FULL
99990074	23	Dissolved Oxygen	15 / 3	4.7	12.9	8.2	1	NA / NA	4	NO	MONITORED	FULL
99990075	23	Dissolved Oxygen	15 / 3	4.5	13.1	8.3	1	NA / NA	4	NO	MONITORED	FULL
10070001	6	pH	35 / 3	7.6	8.7	8.1	0	NA / NA	7	NO	MONITORED	FULL
99990069	23	pH	14 / 3	7.73	8.46	8.13	0	NA / NA	4	NO	MONITORED	FULL
99990074	23	pH	14 / 3	7.73	8.45	8.1	0	NA / NA	4	NO	MONITORED	FULL
99990075	23	pH	14 / 3	7.78	8.47	8.09	0	NA / NA	4	NO	MONITORED	FULL
10070001	6	Sulfate	36 / 3	14	35	25	0	NA / NA	7	NO	MONITORED	FULL
99990069	23	Sulfate	15 / 3	13.8	38.2	23.1	0	NA / NA	4	NO	MONITORED	FULL
99990074	23	Sulfate	15 / 3	12.7	38.1	23.7	0	NA / NA	4	NO	MONITORED	FULL
99990075	23	Sulfate	15 / 3	17.2	36.6	23.8	0	NA / NA	4	NO	MONITORED	FULL
10070001	6	Temperature	36 / 3	0	24	11	0	NA / NA	7	NO	MONITORED	FULL
99990069	23	Temperature	15 / 3	5.7	25.3	17.8	0	NA / NA	4	NO	MONITORED	FULL
99990074	23	Temperature	15 / 3	5	24.5	18	0	NA / NA	4	NO	MONITORED	FULL
99990075	23	Temperature	15 / 3	4.4	24.7	17.8	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
10070001	6	Ammonia	35 / 3	0.28	0.05	0.02	0 / 0	NO	MONITORED	FULL
10070001	6	Cadmium	18 / 2	0.5	0.5	0.5	0 / 0	NO	MONITORED	FULL
10070001	6	Chromium	18 / 2	2	0.8	0.88	0 / 0	NO	MONITORED	FULL
10070001	6	Copper	18 / 2	2.4	0.8	0.5	0 / 0	NO	MONITORED	FULL
10070001	6	Lead	18 / 2	1	1	1	0 / 0	NO	MONITORED	FULL
10070001	6	Nickel	18 / 2	1.6	0.9	0.9	0 / 0	NO	MONITORED	FULL
10070001	6	Selenium	36 / 3	2	0.8	0.5	0 / 0	NO	MONITORED	FULL
10070001	6	Silver	18 / 2	1	1	1	0 / 0	NO	MONITORED	FULL
10070001	6	Zinc	18 / 2	3.3	1.1	0.5	0 / 0	NO	MONITORED	FULL

Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47c BMIBI BIT	BMIBI Pass/ Fail
947	8/12/23	391	47c	MS	Float Art Sub	59	Good	52	Pass
373	8/25/20	375	47c	MS	Art Sub	73	Good	52	Pass

Fish:

Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47c FIBI BIT	FIBI Pass/ Fail
373	8/25/20	375	47c	MS	No	58	Good	44	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Monitored	Pass (2/2)	Full
Fish	Evaluated	Pass (1/1)	Full	1	Assessment was monitored because the BMIBI assessment was
Overall	Monitored	Pass	Full		completed using samples collected in a recent five year period.

Class BWW1 - Continuous DO Monitoring:

Site ID	Data Source ID	# Days Monitoring (2020)	DO Criteria Type	# 2020 violations / Violations needed for impairment	Violates Annual Significantly >10% Rule?	Assessment Type	Support Level
			24 hr	0/4	No
373	6	15	16 hr	0/4	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
10070001	6	Copper	18 / 2	2.4	0.8	0.5	13	NO	MONITORED	FULL
Site ID	Data Source ID	Parameter Name	# Samples per Year (2022/ 2023/2024)	2022 Mean	2023 Mean	2024 Mean	# Non-Detects per Year (2022/ 2023/2024)	Support Level per Year (2022/ 2023/2024)	Assessment Type	Support Level
10070001	6	Selenium	12/12/12	0.875	0.583	1.067	7/10/6	FS/FS/FS	MONITORED	FULL

Monitoring and Methods

Assessment Key Dates

1/11/2022

Monitoring Start

12/9/2024

Monitoring End

8/25/2020

Biological Monitoring

8/12/2023

Biological Monitoring

Methods

200

Physical/Chemical Monitoring

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

420

Indicator bacteria monitoring