Ashton Creek IA 06-LSR-2048

from tributary(T89N R41W Sec3 Ida Co.) to headwaters (T88N R41W Sec2) Ida 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 2018 - 2020
Stream/River Water Quality Data	CY 2018 - 2020
Lake Water Quality Data	CY 2016 - 2020
Biological Sampling Data	CY 2016 - 2020*
Fish Kill Data	CY 2016 - 2020
Fish Tissue Sampling Data	CY 2016 - 2020
Continuous Dissolved Oxygen Sampling Data	CY 2016 - 2020
*Biological sites sampled in both 2015 and 2019 were also assessed.

Open Segment Map
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Cycle: 2022
Release Status: Final
Overall IR: 5 - Water is impaired or threatened and a TMDL is needed.
Trend: Unknown
Created: 1/3/2022 11:13:06 AM
Updated: 2/17/2022 9:20:56 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Not Supported

Organic Enrichment: Low Dissolved Oxygen

Support Level

Not Supported

Impairment Code

5p - Impairment occurs on a waterbody with a presumptive A1 or B(WW1) use.

Cause Magnitude

High

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2010

Impairment Rationale

Violations of acute criterion

Data Source

Biological monitoring: Iowa DNR WQMA

TMDL Priority

Tier IV

Biological: low fish & invert IBIs- cause unknown

Support Level

Further Investigation Needed

Impairment Code

3b-u - Use potentially biologically impaired based on uncalibrated IBI metrics.

Cause Magnitude

Moderate

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

Low

Cycle Added

2008

Impairment Rationale

Low Biotic Index

Data Source

Biological monitoring: Iowa DNR WQMA

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class BWW1 use was assessed as “not supported” based on continuous 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	603	Ashton Creek	Washta - REMAP #209

Presumptive Class A1 - No Data

Presumptive Class BWW1 - Biological Sampling:

Benthic Macroinvertebrates:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/ Thermal	BM Sample Gear	BMIBI score	BMIBI Class	47a BMIBI BIT	BMIBI Pass/ Fail
603	7/7/06	6	47a	MO/WW	ArtSub	20	Poor	51	Fail
603	7/7/06	6	47a	MO/WW	Surber	26	Poor	51	Fail

Fish:

BioNet Site ID	Date	Drainage Area (mi2)	Ecoregion	Major Drainage/ Thermal	Riffle Stream?	FIBI score	FIBI Class	47a FIBI BIT	FIBI Pass/ Fail
603	7/7/06	6	47a	MO/WW	NA	1	Poor	43	Fail

Overall:

Community	Assessment Type	Assessment Result	Support Level	IR Category	Reason
Benthic Macroinvertebrates	Evaluated	Fail (0/2)	Not
Fish	Evaluated	Fail (0/1)	Not
Overall	Evaluated	Fail	WINOFI	3bu	Assessment was evaluated because the drainage area of the site was smaller than the calibrated range.

Presumptive Class BWW1 – Continuous Monitoring Data:

A dissolved oxygen and temperature continuous monitoring data logger was deployed in the stream for 9 days in July/August 2006. The data logger recorded an early morning dissolved oxygen level of 3 mg/L, which is substantially less than the instantaneous criterion of 4 mg/L for Class BWW1 streams. Also, a precipitous drop in DO, to near 0 mg/L was observed, which was accompanied by an elevated ammonia level of 6.1 mg/L on August 3, 2006. This water quality evidence of presumptive Class BWW1 impairment is considered "evaluated" rather than "monitored" because the data were obtained from limited short-term sampling.

Monitoring and Methods

Assessment Key Dates

7/6/2006

Biological Monitoring

Methods

150

Monitoring data more than 5 years old

222

Non-fixed-station monitoring (conventional during key seasons and flows)

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys