Assessment Comments
Assessment remains based on occurrence of a fish kill in April 2000.
Basis for Assessment
SUMMARY: The Class B(LR) aquatic life uses are 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 will be considered “evaluated” and moved from Category 4d (impaired but TMDL not required) to Category 3b (water in need of further investigation) of Iowa's 2006 Integrated Report.
EXPLANATION: A fish kill 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 the most recent three-year period (2000-2002) 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 will be placed in IR Category 4d (impaired but TMDL not required). Thus, this assessment segment was placed into Category 4d of Iowa's 2004 Integrated Report.
According to IDNR’s assessment/listing methodology, if no additional fish kills have occurred over at least a three-year period (i.e., no kill occurred in the period 2002-2004), the assessment of impairment should be considered “evaluated” (i.e., of lower confidence), and the waterbody segment should be moved from IR Category 4d to IR Category 3b (list of waters in need of further investigation).
