Assessment Comments
Assessment based on 1997 and 2009 IDNR/SHL biological sampling data: FIBI = 22, 23 (both poor); BMIBI = 58, 67 (both 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, 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 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" (IR 3a) due to the lack of information upon which to base an assessment. The Class B(WW-2) aquatic life uses are assessed (evaluated) as "partially supported" (IR 4c) based on results of IDNR/SHL biological sampling in 1997 and 2009.
EXPLANATION: The assessment of the Class B(WW2) aquatic life uses was based on the 1997 and 2009 biological assessment data conducted in Lucas Co. approximately six miles south of Lacona. The FIBI scores were 22 and 23 (both poor), and the BMIBI scores were 58 and 67 (both 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 1994-2008. The FIBI BIC for this ecoregion is 33 and the BMIBI BIC for this ecoregion is 41. This segment passed the FIBI BIC 0/2 times and passed the BMIBI BIC 2/2 times in the last 16 years.
This aquatic life assessment is considered "evaluated" because there were not two or more samples collected from this segment in multiple years from over a five-year period. 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.
