West Branch Buffalo Creek IA 01-WPS-381

mouth (S35 T90N R8W Buchanan Co.) to confluence with unnamed tributary in S9 T90N R8W Buchanan Co.

Assessment Cycle

2018

Release Status

Final

Data Collection Period

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 2014 - 2016
Stream/River Water Quality Data	CY 2014 - 2016
Lake Water Quality Data	CY 2012 - 2016
Biological Sampling Data	CY 2012 - 2016*
Fish Kill Data	CY 2012 - 2016
Fish Tissue Sampling Data	CY 2012 - 2016
Continuous Dissolved Oxygen Sampling Data	CY 2012 - 2016
*Biological sites sampled in both 2011 and 2015 were also assessed.

Overall IR Category: 3 - Insufficient data exist to determine whether any designated uses are met.
Trend: Unknown

Created: 8/1/2019 2:05:28 PM
Updated: 8/1/2019 2:06:50 PM

Assessment conducted in accordance with Iowa's 2018 IR methodology

Use Support

Class A1

Recreation

Primary contact

Presumptive Use

Not Assessed

Class BWW2

Aquatic Life

Warm Water Type 2

WINOFI

Further Investigation Needed

Support Level

Water in Need of Further Investigation (WINOFI)

Impairment Code

3b - Use potentially impaired based on an evaluated assessment.

Cause Magnitude

Slight

Status

Continuing

Source

Unknown: Source Unknown

Source Confidence

N/A

Cycle Added

2016

Impairment Rationale

Potential Impairment

Data Source

Watershed project monitoring

General Use

General Use water

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

SUMMARY: The presumptive Class A1 (primary contact recreation) uses remain “not assessed” (IR 3a) due to the lack of information on indicator bacteria upon which to base an assessment. The Class B(WW2) aquatic life uses are assessed (monitored) as “partially supported” (IR 3b). The source of data for this assessment is the results of water quality monitoring in 2008 at Buffalo Creek Site 1 of the Section 319 water quality monitoring project (STORET station 15100001). This station is located SSW of Aurora along Quonset Avenue in Buchanan County.

Assessment Explanation

The presumptive Class A1 uses remain not assessed: Section 319 monitoring at this site did not include analysis for indicator bacteria.

The Class B(WW2) aquatic life uses are assessed (evaluated) as “partially supported” based on results of Section 319 monitoring at Buffalo Creek Site 3 from June to September 2008. While none of the 21 samples collected contained levels of ammonia, pH, or water temperature that violated Class B(WW1) water quality criteria, four of the 21 samples (19%) contained levels of dissolved oxygen that violated the Class B(WW2) water quality criterion of 5 mg/l. The four violations ranged from 2.5 mg/l to 4.9 mg/l and occurred from mid-August through early October. According to U.S. EPA guidelines for Section 305(b) reporting, if more than 10% of samples exceed state criteria for conventional parameters such as dissolved oxygen, the aquatic life uses should be assessed as "impaired" (see pgs 3-33 to 3-35of U.S. EPA 1997b). According to DNR’s assessment/listing methodology, the results from station Buffalo Creek Site 1, however, do not suggest that significantly greater than 10% of the samples violated the Class B(WW2) criterion for dissolved oxygen. Despite indications of “full support”, the occurrence of four violations of the Class B(WW2) criterion for dissolved oxygen suggests a potential impairment. Thus, the aquatic life uses are considered potentially impaired, and this segment will be added to Iowa’s list of waters in need of further investigation.

Monitoring and Methods

Assessment Key Dates

6/23/2008

Fixed Monitoring Start Date

12/12/2008

Fixed Monitoring End Date

Methods

220

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