Mud Creek IA 02-CED-488

mouth (S10 T78N R2W Muscatine Co.) to confluence with unnamed tributary in S5 T78N R1E Muscatine Co.

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.

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Cycle: 2020
Release Status: Final
Overall IR: 4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend: Unknown
Created: 8/31/2020 8:58:31 AM
Updated: 10/16/2020 8:19:34 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

Partially Supported

Biological: low fish & invert IBIs- cause unknown

Support Level

Partially Supported

Impairment Code

4a - Pollutant-caused impairment. TMDL has been completed.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

1998

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class BWW2 use remains assessed as "partially supported" based on biological sampling data. All other designated uses were "not assessed". Note: A TMDL for organic enrichment in Mud Creek was prepared by DNR and approved by EPA in 2003; thus, this waterbody was placed into IR Category 4a (TMDL approved) for the 2004 assessment/listing cycle. Because all Section 303(d) impairments identified (organic enrichment, nutrient, and siltation) are potentially addressed by the TMDL, this waterbody remains in IR Category 4a.

Assessment Explanation

Sources of Data:

Data Source	Data Source ID	Data Type	Data Age	Site ID	Site Name	Site Description
Iowa DNR	6	BIO	See Below	386	Mud Creek	Wilton – Site 1
Iowa DNR	6	BIO	See Below	385	Mud Creek	Wilton – Site 3
Iowa DNR	6	BIO	See Below	384	Mud Creek	Wilton – Site 4

Presumptive Class A1 - No Data

Class BWW2 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	BM Sample Gear	BMIBI score	BMIBI Class	47f BMIBI BIT	BMIBI Pass/ Fail
384	9/15/03	74	47f	MS/WW	ArtSub	42	Fair	51	Fail
385	9/15/03	97	47f	MS/WW	ArtSub	39	Fair	51	Fail
386	9/15/03	105	47f	MS/WW	ArtSub	50	Fair	51	Fail

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage	Riffle Stream?	FIBI score	FIBI Class	47f FIBI BIT	FIBI Pass/ Fail
385	9/17/03	97	47f	MS/WW	NA	27	Fair	36	Fail
384	9/16/03	74	47f	MS/WW	NA	25	Poor	36	Fail
386	9/16/03	105	47f	MS/WW	NA	40	Fair	36	Pass

Overall:

Community	Assessment Type	Assessment Result	Support Level	Earned IR Category	Actual IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/3)	Partial
Fish	Evaluated	Fail (1/3)	Partial
Overall	Evaluated	Fail	Partial	3bc	4at	Assessment is evaluated because it was based on samples not collected in the last five years.

Class BWW2 - Historical Assessment:
Results of monitoring conducted in 2001 in support of TMDL development showed only one violation of Class BWW2 water quality criteria for conventional parameters and ammonia-nitrogen in the nine monthly samples collected between March and November 2001: the level of dissolved oxygen in the sample collected at Site 3 downstream from Durant on August 16, 2001 (4.7 mg/l) violated the water quality criterion of 5.0 mg/l. Although no violations of Class BWW2 criteria for ammonia-nitrogen occurred, the maximum levels were moderately high for Iowa streams (downstream to upstream): 0.48 mg/l at Site 1 SE of Wilton, 0.70 mg/l at Site 2 upstream from Wilton, 0.49 mg/l at Site 3 downstream from Durant, 0.42 mg/l at Site 4 at the SE edge of Durant, and 0.19 mg/l at Site 5 upstream from Durant. Four of the six maximum ammonia values occurred on August 16.

Additional TMDL-related monitoring was conducted from June to September 2003 at four stations on Mud Creek: three stations are near Wilton (DNR stations 11700006, 11700007, and 11700008); one station is located west of Durant (11700005). Five samples were collected at each station during the June-September period and the samples were analyzed for ammonia, dissolved oxygen, pH, and temperature. No violations of Class BWW2 criteria for ammonia, pH, or temperature occurred in the combined 20 samples. At station TMDL S2 (11700007), however, three of the five samples violated the Class BWW2 criterion for dissolved oxygen (5.0 mg/l). Although violations were relatively minor (the minimum value was 4.5 mg/l), these results suggest the potential for an ongoing water quality impairment in this segment of Mud Creek.

Despite the indications of relatively good water quality from TMDL-related monitoring in 2001 and 2003, biological monitoring is better able to reflect cumulative impacts of water quality over time and thus is believed to more accurately represent water quality conditions of this segment of Mud Creek than do results from the 2001 or 2003 TMDL monitoring sites. Thus, the assessment of support of the designated aquatic life uses for this segment (partially supported) remains based on results of biological monitoring.

Monitoring and Methods

Assessment Key Dates

3/14/2001

Non-fixed Monitoring Start Date

11/14/2001

Non-fixed Monitoring End Date

6/19/2003

Non-fixed Monitoring Start Date

9/9/2003

Non-fixed Monitoring End Date

9/16/2003

Biological Monitoring

9/17/2003

Biological Monitoring

9/15/2003

Biological Monitoring

7/1/2003

TMDL Completed

Methods

150

Monitoring data more than 5 years old

220

Non-fixed station physical/chemical monitoring (conventional pollutant only)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys