Assessment Comments
Assessment remains based on 1997 IDNR/UHL biological monitoring data: FIBI = 23 (poor), BMIBI = 57 (good). FIBI BIC = 33, BMIBI BIC = 41.
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(WW-2) aquatic life uses remain assessed (evaluated) as "partially supported" based on results of IDNR/UHL biological (biocriteria) sampling in 1997. This is the same assessment as that developed for the 2004 reporting cycle but now the data are old enough for this assessment to be considered evaluated.
EXPLANATION: The assessment of the Class B(WW2) aquatic life uses was based on the 1997 biological assessment data conducted in Lucas Co. approximately six miles south of Lacona. The FIBI score was 23 (poor), and the BMIBI score was 57 (good). The aquatic life use support status was assessed (evaluated) as partially supporting (=PS), based on a comparison of the FIBI and BMIBI scores 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 33 and the BMIBI BIC for this ecoregion is 41.
This aquatic life assessment is considered "evaluated" because there were not two or more samples collected from this segment in multiple years from 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). Although these data have now aged beyond 10 years and are thus to old to accurately characterize current biological and water quality conditions, the identification of an impairment suggests that this segment should remain in IR category 4c until follow-up monitoring can be conducted to better assess current conditions.
