Duck Creek IA 01-UIA-254
mouth (NE 1/4 S14 T100N R6W Allamakee Co.) to IA/MN state line (S11 T100N R6W Allamakee Co.).
The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as “partially supported” (IR 5p) due to violations of Iowa water quality criteria for indicator bacteria. The presumptive Class A2 (secondary contact recreation) uses are assessed as "fully supporting". The presumptive aquatic life uses are assessed (monitored) as "fully supported" (IR 2a) based on the January 2016 summary of trout reproduction in Iowa streams as prepared by the IDNR Fisheries Bureau and based on results of water quality monitoring in 2011. Although not designated for coldwater aquatic life uses in the Iowa Water Quality Standards/Surface Water Classification, this stream is considered a trout stream by the IDNR Fisheries Bureau and is identified as an "Outstanding Iowa Water" as part of Iowa's anti-degradation program. Thus, this stream segment is assessed as a coldwater stream for the Iowa’s Integrated Reporting cycle. The sources of data for this assessment include (1) the results of monitoring from April 2010 to November 2011 at station Duck Creek 1 (STORET station 13030001) and (2) results of an IDNR Fisheries Bureau trout reproduction survey updated in February 2012.
The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as "partially supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric means of indicator bacteria (E. coli) in the 19 samples collected during the recreational season of 2010 (530 orgs/100 ml) exceeded the Class A1 criterion of 126 orgs/100 ml. The geometric mean of the 11 samples collected during 2011 (90 orgs/100 ml), however, was below the Class A1 criterion. Sixteen of the combined 30 samples (53%) exceeded Iowa’s single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if a recreation season geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). [Note: Results of bacteria monitoring suggest that, if this stream were designated for Class B(CW1)/A1/A2 uses, the Class A2 uses would be assessed as “fully supporting” based on the available data for indicator bacteria.]
The aquatic life uses of this stream segment remain assessed (monitored) as “fully supporting”. Results of chemical/physical water quality monitoring conducted at site Duck Creek 1 (STORET station 13030001) from June to November 2011 show no violations of Class B(CW1) water quality criteria for dissolved oxygen (seven samples) or temperature (11 samples) collected. The maximum temperature was 18.2C, and the minimum dissolved oxygen was 7 mg/l, thus suggesting that this stream segment functions as a coldwater stream.
Based on an updated summary of trout reproduction in Iowa streams prepared by the IDNR Fisheries Bureau in January 2016, the presumptive aquatic life uses are assessed as "fully supported". According to the updated summary, Duck Creek is in the group of Iowa coldwater streams that supports natural reproduction of trout. Based on results of surveys by the IDNR Fisheries Bureau, this stream is placed in the category of Iowa trout Streams that exhibit fairly consistent natural reproduction and maintain a viable population of the listed species (Brown Trout) without any stocking (a Category I stream).