Clear Creek IA 02-IOW-1937

from confluence with tributary in Sec. 22 T80N R9W (Iowa Co.) to headwaters in S28 T80N R10W (Iowa 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 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.

Open Segment Map
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Cycle: 2018
Release Status: Final
Overall IR: 2 - Some of the designated uses are met but there is insufficient data to determine if remaining designated uses are met.
Trend: Unknown
Created: 7/29/2019 7:54:03 AM
Updated: 7/29/2019 7:55:47 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Fully Supported

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Not Assessed

General Use

General Use water -

Fully Supported

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The general uses and the presumptive Class A1 (primary contact recreation) uses of this stream remain assessed as "fully supported" based on a follow-up investigation by DNR field office staff of historical impacts of poorly-treated and untreated domestic wastewater discharged to the stream near Conroy, IA. The presumptive Class B(WW1) aquatic life uses remain "not assessed" due to lack of information upon which to base an assessment. The source of information upon which this assessment was based remains a July 7, 2009 memorandum from DNR Field Office 6 staff describing improved water quality conditions in this segment of Clear Creek.

Assessment Explanation

Historically the water quality conditions in this segment of Clear Creek as documented by volunteer monitors and by DNR staff potentially violated several of Iowa's narrative water quality standards designed to protect general uses of Iowa's surface waters. The assessment of impairment was originally based on results of an DNR/IOWATER “snapshot” monitoring event in September 2003 that showed presence of toilet paper, floating sewage material, and a strong sewage smell coming from a tile line that discharges to the uppermost reaches of Clear Creek near Conroy, IA (see DNR Water Fact Sheet 2005-2: Snapshot Events; see also Neely et al. 2003. Old Man’s Creek and Clear Creek, east-central Iowa: the role of volunteers in a snapshot sampling). Subsequent investigations by volunteer (IOWATER) monitors and by DNR staff confirmed that these impacts existed. Based on these investigation, the general uses of this stream, as well as the presumptive aquatic life uses and the presumptive primary contact recreation uses of this segment, were assessed as impaired for the 2004 listing cycle. This impairment remained on Iowa’s 2006 and 2008 Section 303(d) lists. Due to the February 2008 EPA approval of changes to Iowa Water Quality Standards that presumed Class A1 and Class B(WW1) uses for all Iowa perennial streams, this impairment was added to the presumptive Class A1 (primary contact recreation) and Class B(WW1) aquatic life uses of this segment of Clear Creek.

A follow-up investigation by staff from DNR Field Office 6 (Washington, IA) on July 1, 2009 showed improved water quality conditions with no evidence of untreated or poorly-treated wastewater being discharged to the stream. Thus, the general uses and the presumptive Class A1 uses were assessed as “fully supported” for the 2012 assessment/listing cycle, and the wastewater-related impairment of these uses was proposed for de-listing. The wastewater-related impairment identified for the 2008 cycle was incorrectly applied to the Class B(WW1) aquatic life uses: there were (and are) no data available upon which to develop a valid assessment of the degree to which the aquatic life uses of this stream segment are supported. Thus, the wastewater-related impairment of the aquatic life uses was de-listed, and the aquatic life uses remain "not assessed" due to the lack of water quality information upon which to base an assessment.

Monitoring and Methods

Assessment Key Dates

7/1/2009

DNR Stream Use Assessment

Methods

110

Information from local residents

120

Surveys of fish and game biologists/other professionals

150

Monitoring data more than 5 years old