2020 assessment for Otter Creek

Otter Creek IA 02-IOW-6232

from confluence with unnamed tributary(SE1/4 S4 T73N R3W Louisa Co.) to headwaters (T73N R4W Sec16 Louisa Co.)

2020
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.

Open Segment Map
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Overall IR

3 - Insufficient data exist to determine whether any designated uses are met.

Trend

Unknown

Created

6/4/2020 12:40:58 PM by

Updated

10/9/2020 8:04:41 AM by

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

Not Assessed

General Use

General Use water -

Not Assessed

303(d) Delistings for this Cycle

No delistings for this assessment cycle.

Documentation

Assessment Summary

Insufficient water quality information available to assess use support.

Assessment Explanation

The Class BWW1 aquatic life use previously resided in IR Category 3b based on the assessment developed for the 2007 fish kill. Because no additional fish kills were reported in this segment for at least 10 years post fish kill (2017), the IR Category for the fish kill assessment was changed from 3b to 3a (water not assessed). DNR believes that any impact from the fish kill from which the impairment was based has likely dissipated.

Monitoring and Methods

Assessment Key Dates

None listed

Methods

None listed