Assessment Comments
Assessment remains based on 2004 UHL special project sampling data: 2/4 coldwater biological indicators met the criteria - Partially Supporting (PS).
Basis for Assessment
[Note: Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(CW) aquatic life uses. Due to changes in Iowa’s surface water classification that were approved by U.S. EPA in February 2008 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), this segment is also now presumptively designated for Class A1 (primary contact recreation) and Class A2 (secondary contact recreation) uses. This segment remains designated for coldwater aquatic life use (now termed Class B(CW1) uses), and for fish consumption uses (now termed Class HH (human health/fish consumption) uses.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses and the presumptive Class A2 (secondary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment. The Class B(CW1) coldwater aquatic life uses remain assessed (evaluated) as "partially supported" based on results of biological monitoring in 2004. Fish consumption uses remain not assessed. The source of data for this assessment is results of UHL special project monitoring in 2004.
EXPLANATION: The assessment of the Class B(CW1) coldwater aquatic life uses was based on data collected in 2004 as part of a UHL stream sampling special project. A series of four (4) coldwater biological indicators, which reflect stream water quality and habitat integrity, were calculated from the biocriteria sampling data. The coldwater biological indicators are based on the numbers and types of coldwater benthic macroinvertebrate taxa that were collected in the stream sampling reach. Sites that do not receive any type of trout stocking are scored on the benthic macroinvertebrate data only. Non-trout stocking sites that score 3 or 4 are Fully Supporting (FS), sites that score 1 or 2 are Partially Supporting (PS), and sites that score 0 are Not Supporting (NS). The 2004 coldwater biological indicator score was 2/4. The aquatic life use support was assessed (monitored) as Partially Supporting (=PS), based on a comparison of the coldwater biological indicator score with biological assessment criteria established for this Section 305(b) report. The coldwater biological indicators were determined from a statistical analysis of data collected at coldwater stream ecoregion reference sites from 1994-2008 and with assistance from the IDNR Fisheries Bureau.
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 between 2004 and 2008 to be considered “monitored”. This segment had a single sample collected in 2004. According to IDNR’s assessment/listing methodology, impairments based on “evaluated” assessments are of lesser confidence and are thus not appropriate for Section 303(d) listing (Category 5 of the Integrated Report). IDNR does, however, consider these impairments as appropriate for listing under either Category 2b or 3b of the Integrated Report (waters potentially impaired and in need of further investigation). However, despite this change in assessment methodology and type, this waterbody remains in IR Category 5b and remains on Iowa’s 2010 Section 303(d) list of impaired waters.
This site is approximately 1/10th of a mile from the upper end of the cold water segment. At this time, IDNR does not know if the spring is above or below the sampling site and if the sampling data should be judged on a cold or warm water basis. The information below is an additional assessment based on warm water criteria.
The additional assessment of the aquatic life uses based on data collected in 2004 as part of a UHL special project. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biocriteria sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and 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) and a benthic macroinvertebrate index (BMIBI). The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2004 FIBI score was 74 (excellent) and the BMIBI score was 74 (good). If the segment was designated warm water, the aquatic life use support would be assessed (evaluated) as fully supporting (=FS), based on a comparison of the FIBI score with biological impairment criteria (BIC) established from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004. The FIBI BIC for this ecoregion is 62 and the BMIBI BIC is 61.
Fish consumption uses remain "not assessed" due to lack of fish tissue monitoring in this stream reach.
