Beaver Creek IA 04-UDM-1235

from confluence with Slough Cr. to confluence with unnamed tributary in S29 T84N R28W Boone 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 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.

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Cycle: 2016
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: 9/20/2016 2:22:27 PM
Updated: 10/12/2016 1:42:17 PM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW2

Aquatic Life - Warm Water Type 2

Fully Supported

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(WW2) aquatic life uses remain assessed (monitored) as "fully supported” (IR Category 2a). Assessment based on (1) results of IDNR/SHL biological sampling in 2001 and 2011 and (2) results of USGS chemical/physical water quality monitoring at Beaver Creek near Bouton in 2013.

Assessment Explanation

The Class B(WW2) aquatic life uses are assessed (evaluated) as “fully supporting” based on data collected in 2001 and 2011 as part of the IDNR/UHL stream biocriteria project. The 2001 FIBI scores were 38, 45 (fair) and the BMIBI scores were 48 (fair) and 65 (good). The 2011 FIBI score was 54 (good) and the BMIBI score was 67 (good). The aquatic life use support was assessed as fully supported (=FS), based on a comparison of the FIBI and BMIBI scores 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 non-riffle habitat FIBI BIC for this ecoregion is 32 and the BMIBI BIC for this ecoregion is 62. This segment passed the FIBI BIC 3/3 times and passed the BMIBI BIC 2/3 times in the last 14 years.

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 recent five-year period to be considered “monitored”. This segment had multiple samples collected in the previous 14 years (2001-2014); however, the multiple samples were not collected during a recent five-year period.

Results of chemical/physical water quality monitoring Beaver Creek near Bouton also suggest “monitored/full support” of the aquatic life uses. Monitoring showed no violations of Class B(WW2) water quality criteria for 11 Ammonia samples (maximum = 0.05 mg/L), 11 pH samples (range = 7.4 to 8.2), 11 Temperature samples (maximum = 25.5° c), 11 Chloride samples (maximum = 35.3 mg/L), or 11 Sulfate samples (maximum = 51.7 mg/L) occurred during monitoring from May 2013 to August 2013. One of the 11 samples (9%) analyzed for Dissolved Oxygen (minimum = 4.5 mg/L) violated the Class B(WW2) criteria during the 2013-2013 monitoring period. According to U.S. EPA guidelines (U.S. EPA 1997b, page 3-17), a violation frequency of greater than 10% for conventional parameters such as Dissolved Oxygen suggests impairment of aquatic life uses. Because the frequency of violations for this parameter is not greater than 10 percent, these results do not suggest impairment of the Class B(WW2) aquatic life uses.

Monitoring and Methods

Assessment Key Dates

7/25/2001

Biological Monitoring

10/16/2001

Biological Monitoring

8/11/2011

Biological Monitoring

5/7/2013

Fixed Monitoring Start Date

8/6/2013

Fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

220

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

315

Regional reference site approach

320

Benthic macroinvertebrate surveys

330

Fish surveys

380

Quantitative physical habitat assessment