Otter Creek IA 01-WPS-389

mouth S19 T89N R9W Buchanan Co.) to dam of Lake Oelwein in S 1/2 S33 T91N R9W Fayette Co.

Assessment Cycle

2016

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 2012 - 2014
Stream/River Water Quality Data	CY 2012 - 2014
Lake Water Quality Data	CY 2010 - 2014
Biological Sampling Data	CY 2010 - 2014*
Fish Kill Data	CY 2010 - 2014
Fish Tissue Sampling Data	CY 2010 - 2014
Continuous Dissolved Oxygen Sampling Data	CY 2010 - 2014
*Biological sites sampled in both 2009 and 2013 were also assessed.

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

Created: 9/23/2016 8:15:47 AM
Updated: 11/30/2016 8:16:50 AM

Assessment conducted in accordance with Iowa's 2016 IR methodology

Use Support

Class A1

Recreation

Primary contact

Presumptive Use

Not Assessed

Class BWW1

Aquatic Life

Warm Water Type 1

Not Assessed

Class HH

Human Health

Not Assessed

General Use

General Use water

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The presumptive Class A1 (primary contact recreation) uses remain "not assessed" (IR 3a) due to the lack of information upon which to base an assessment. The Class B(WW1) aquatic life uses are now considered "not assessed" based on results of IDNR Fisheries biological monitoring in 1998. Due to the age of these data (>10 years), the aquatic life uses are now considered "not assessed" (IR 3a).

Assessment Explanation

Assessment historically based on 1998 Fisheries data (see below). Due to the age of these data (>10 years), the aquatic life uses are now considered "not assessed".

The Class B(WW1) aquatic life uses was were assessed (evaluated) as “partially supporting” based on data collected in 1998 as part of an IDNR Fisheries stream sampling project: Manchester research station. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the Fisheries sampling data. The biological metrics are based on the numbers and types of fish species that were collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (FIBI). The index ranks the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 1998 FIBI score was 90 (excellent). The aquatic life use support was assessed (evaluated) as fully supporting (=FS), based on a comparison of the FIBI score with biological impairment criteria (BIC) established for previous Section 305(b) reports. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008. The riffle site FIBI BIC for this ecoregion is 65. Another Fisheries Bureau FIBI sample (2001: 45) was historically used for this assessment erroneously. That sample was collected in another stream segment (06-BSR-1542) and those data should have been used to assess that segment. However, those data are also too old (>10 years) to use for assessment purposes.

This aquatic life assessment is now considered "evaluated" based on a change in the 2010 IDNR assessment methodology. IDNR now requires a segment have two or more biological samples collected from the segment in multiple years over a five-year period to be considered “monitored”. Additionally, because these data are now considered too old (greater than ten years) to accurately characterize current water quality conditions, the assessment category is considered “evaluated” (indicating an assessment with relatively lower confidence) as opposed to "monitored" (indicating an assessment with relatively higher confidence).

Monitoring and Methods

Assessment Key Dates

None listed

Methods

150

Monitoring data more than 5 years old