Storybook Hollow IA 01-TRK-118
mouth (S7 T86N R4E Jackson Co.) to S line of S12 T86N R3E Jackson Co.
- 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
- 8/23/2016 11:01:40 AM
- Updated
- 10/5/2016 9:24:00 AM
The Class A1 (primary contact recreation) uses and the Class A2 (secondary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment (IR Category 3a). The Class B(CW1) coldwater aquatic life uses are assessed (evaluated) as "fully supported" (IR Category 2a) based on 2007 IDNR/SHL benthic macroinvertebrate sampling data and on the January 2016 summary of trout reproduction in Iowa streams prepared by the IDNR Fisheries Bureau. Fish consumption (Class HH) uses remain "not assessed" (IR Category 3a).
The Class A1 (primary contact recreation) uses and the Class A2 (secondary contact recreation) uses remain "not assessed" due to the lack of data for indicator bacteria upon which to base an assessment.
The assessment of the Class B(CW1) aquatic life uses was based on data collected in 2007 as part of the IDNR/SHL coldwater stream sampling project. A series of biological metrics which reflect coldwater stream water quality and habitat integrity were calculated from the biological sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa that were collected in the stream sampling reach. The biological metrics were combined to make a coldwater benthic index (CBI). The index ranks the biological integrity of a coldwater stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2007 CBI score was 57. The aquatic life use support was assessed (evaluated) as fully supporting (=FS), based on a comparison of the CBI score with biological impairment criteria (BIC) established for the 2012 Section 305(b) report. The biological impairment criteria were determined from a statistical analysis of data collected at coldwater stream reference sites from 1994-2011. The CW BIC is 60 and this segment passed the CW BIC 1/1 times in 2007 with the aid of the 8 point CBI UAV (uncertainty adjustment value) applied to single samples.
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”. This segment had a single sample collected in 2007. Additionally, these data are now greater than five years old. Despite this change in assessment methodology and type, this waterbody remains placed in IR Category 2a.
The Class B(CW1) coldwater aquatic life uses are also assessed (evaluated) as “fully supporting” based on an updated summary of trout reproduction in Iowa streams prepared by the IDNR Fisheries Bureau in January 2016. According to the updated summary, Storybrook Hollow is in the group of Iowa coldwater streams that supports natural reproduction of trout. Based on results of surveys by the IDNR Fisheries Bureau, this stream is placed in the category of Iowa trout streams that exhibit fairly consistent natural reproduction and maintain a viable population of Brown Trout without any stocking (a Category I stream).
Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream reach.