Elk Run IA 02-CED-544

Assessment Comments

Assessment historically based on 1999 IDNR/SHL biological sampling data: FIBI = 73 (excellent), BMIBI = 64 (good). Non-riffle habitat FIBI BIC = 44, natural substrate BMIBI BIC = 70. Assessment of aquatic life uses changed from "fully supporting" to "not assessed" for the 2012 cycle due to age of data (> 10 years).

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/EXPLANATION:  The presumptive Class A1 (primary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment.   The previous (2010) assessment of the Class B(WW2) aquatic life uses was changed from “fully supporting” to “not assessed” for the 2012 IR cycle due to age of the data upon which the assessment was based.   That is, because the data upon which these assessment were based are now more than ten years old, the Class B(WW2) uses are now considered “not assessed.”  As water quality data age, they are less able to represent current water quality conditions.   As data age beyond ten years, their ability to represent current water quality conditions is increasing suspect.   Additional monitoring is needed in this assessment segment to update status of its aquatic communities.