Durion Creek IA 01-NMQ-107

Assessment Comments

Assessment remains based on occurrence of a fish kill in April 2000.

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, and due to U.S.  EPA approval of a use attainability analysis (UAA) by Iowa DNR, this segment is now also designated for Class A3 (children’s recreation) uses.   The stream remains designated for aquatic life uses (now termed Class B(WW2) aquatic life uses).  

SUMMARY:  The Class A3 (children's recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment.   The Class B(WW2) aquatic life uses were assessed (evaluated) as "partially supported" based on a report of a fish kill in April 2000.   Due to the absence of additional kills subsequent to the April 2000 kill, this assessment segment was considered “evaluated” and was moved from Category 4d (impaired but TMDL not required) to Category 3b (water in need of further investigation) of Iowa's 2006 Integrated Report.   Because no additional kills have been reported for this stream for over 10 years, this segment is being moved to IR Category 3a (not assessed) for the 2012 cycle.  

EXPLANATION:  The Class A3 (children’s recreation) uses are "not assessed" due to the lack of data for indicator bacteria upon which to base an assessments.  

The Class B(WW2) aquatic life uses were assessed (evaluated) as "partially supported" due to a fish kill that occurred on this stream reach on April 9, 2000.   The kill began near Worthington in Section 31, T88N, R2W in Dubuque County and affected Durion Creek to its confluence with the N.   Fk.   Maquoketa River; approximately 11,600 fish were killed.   The kill was caused by a discharge of 28% nitrogen fertilizer from an agricultural chemical dealer at Worthington.  

According to DNR's assessment methodology for Section 305(b) reporting, occurrence of a single pollution-caused fish kill during an assessment period indicates "partial support" of the aquatic life uses.   If, however, a consent order has been issued to the party responsible for the kill and monetary restitution has been sought for the fish killed, the affected waterbody should be placed in IR Category 4d (impaired but TMDL not required).   Thus, this segment was placed in Category 4d of Iowa’s 2004 Integrated Report.   IDNR considers IR 4d fish kill waters with no subsequent kills reported in at least five year subsequent to the kill as appropriate for movement from IR Category 4d to either categories 2b or 3b (i.e., Iowa’s list of waters in need of further investigation).   Thus, this assessment segment was moved to Category 3b of Iowa’s 2006 Integrated Report where it will remained until the current (2012) cycle when it was moved to IR Category 3a (not assessed).