Unnamed Tributary to Williamson Pond IA 04-LDM-1965

Williamson Pond to headwaters

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 7:30:40 AM
Updated: 7/29/2019 7:31:37 AM

Use Support

Class A1

Presumptive Use

Recreation - Primary contact

Not Assessed

Class BWW1

Presumptive Use

Aquatic Life - Warm Water Type 1

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” due to the lack of information upon which to base an assessment. The presumptive Class B(WW1) aquatic life uses are assessed as “fully supported” based on results of chemical/physical water quality monitoring during 2005. The source of data for this assessment remains the results of DNR/SHL water quality monitoring conducted as part of TMDL development from March through June 2005 at station 11590001.

Assessment Explanation

The presumptive Class B(WW1) aquatic life uses remain assessed (evaluated) as “fully supported” based on results of DNR/SHL TMDL-related water quality monitoring conducted in 2005 at station 11590001. Results of this monitoring show no violations of Class B(WW1) water quality criteria for conventional parameters dissolved oxygen or pH) or for ammonia in the five monthly samples collected from March-June 2005. The number of samples collected at this station (five) is relatively low and does not meet DNR guidelines for developing a “monitored” (higher confidence) assessment (i.e., at least 10 samples collected over a three-year period). Thus, the assessment type is considered “evaluated” (lower confidence). Also, because these data are now more than five years old, and because as data age beyond five years they are less able to represent current water quality conditions, the assessment type is considered “evaluated” (a lower-confidence assessment.)

Monitoring and Methods

Assessment Key Dates

3/15/2005

Fixed Monitoring Start Date

6/20/2005

Fixed Monitoring End Date

Methods

150

Monitoring data more than 5 years old

220

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