Assessment Comments
Stream use assessment in Jackson County. Fish kills south of Maquoketa in 1997. Monitoring by DNR/LTRMP staff.
Basis for Assessment
Used occurrence of two fish kills in summer 1997 to assess support of aquatic life uses as PS. Kills occurred on August 20 and September 18, 1997. No cause or source was identified for the August kill; the cause of the second kill was determined to be discharge of hog manure from an open feedlot. An estimated 93,000 fish were killed. Stream was also monitored as part of assessment of sediment/ nutrient contributions of watershed in the Maquoketa River basin; monitoring was conducted by DNR/LTRMP staff from Bellevue. The Prairie Creek watershed was identified as one of the six subwatersheds that contribute the highest levels of suspended solids and nutrients to the Maquoketa River and to Pool 13 of the Mississippi River. Thus, the assessment of the Class B(LR) aquatic life uses as PS is appropriate. Under the guidance of the Maquoketa River Alliance, several groups (e.g., NRCS and county extension) are working to address problems with nonpoint source contributions of suspended solids and nutrients (phosphorus). Additional monitoring is needed to determine whether the relatively high levels of suspended solids and nutrients identified through DNR/LTRMP monitoring are impairing the Class B(LR) aquatic life uses of this stream. A review of the field sheet from the September 1991 DNR stream use assessment shows (1) relatively poor fish community diversity (6 cyprinid species) for streams in the Southern Iowa Rolling Loess Prairies subecoregion (47f) and (2) less than a majority of the expected fish taxa (4 of 9) for streams in this subregion. Habitat quality is approximately average for this area, with diverse substrates and a few pool/riffle sequences (i.e., habitat quality is easily sufficient to allow full support of the Class B(LR) uses). As noted above, additional monitoring is needed to (1) update this assessment, (2) determine the status of the aquatic communities, especially with regard to the fish kills in 1997, and (3) determine the signficance of the high levels of suspended solids and nutrients identified through LTRMP runoff monitoring in 1996.
