Assessment Comments
Assessment is based on 1996 & 2002 IDNR/UHL biological monitoring data: FIBI = 21 (poor), 34 (fair), BMIBI = 51 (fair), 64 (good); and on 2002 Fisheries data: FIBI = 23 (poor) and 41 (fair). FIBI BIC = 31, BMIBI BIC = 54.
Basis for Assessment
[Note: Prior to the 2008 Section 305(b) cycle, this stream segment was designated only for Class B(LR) 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 now presumptively designated for Class A1 (primary contact recreation) uses. The stream remains designated for aquatic life uses (now termed Class B(WW2) aquatic life uses). Thus, for the current (2010) assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW2) water quality criteria.]
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 Class B(WW2) aquatic life uses are assessed (evaluated) as "partially supported" based on results of 1996 and 2002 IDNR/UHL biological (biocriteria) and IDNR Fisheries sampling in 2002.
EXPLANATION: The Class B(WW2) aquatic life uses remain assessed (evaluated) as “partially supporting” based on biological data collected in 1996 and 2002 as part of the IDNR/UHL stream biocriteria project and on data collected in 2002 as part of a DNR Fisheries stream sampling project: Cold Springs Fish Management. The 1996 IDNR/UHL FIBI score was 21 (poor) and the BMIBI score was 51 (fair). The 2002 IDNR/UHL FIBI score was 34 (fair) and the BMIBI score was 64 (good). The 2002 IDNR Fisheries FIBI scores were 23 (poor) and 41 (fair). The aquatic life use support was assessed as partially supporting (=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 1994-2004. The FIBI BIC for this ecoregion is 31 and the BMIBI BIC for this ecoregion is 54. This segment passed the FIBI BIC 2/4 times and passed the BMIBI BIC 1/2 times in the last 13 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 between 2004 and 2008 to be considered “monitored”. This segment had multiple samples collected in the previous 13 years (1996-2008); however, the multiple samples were not collected during 2004-2008. Additionally, because these data are now considered too old (greater than five 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). 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).
