Assessment Comments
Assessment remains based on results of a November 1994 IDNR stream use assessment.
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 (see http://www.iowadnr.com/water/standards/files/06mar_swc.pdf), 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 (2010) assessment, the available water quality monitoring data will be compared to the applicable Class A1 and Class B(WW2) water quality criteria.]
SUMMARY: The presumptive Class A1 (primary contact recreation) uses remain "not assessed" due to the lack of information upon which to base an assessment. The Class B(WW2) aquatic life uses remain assessed (evaluated) as "partially supported" based on results of biological monitoring and habitat assessment conducted as part of the November 1994 IDNR stream use assessment. Although the data upon which this assessment were originally based have aged well beyond 10 years--and are thus considered too old to characterize current water quality conditions--the indication of a potential impairment suggests that this stream segment should remain assessed (evaluated) as "partially supported" and thus remain in Category 3b of Iowa’s Integrated Reports (i.e., on Iowa's list of waters in need of further investigation). Excerpts from the assessment developed for the 2004 assessment/listing cycle are included below.
EXPLANATION: Continue to use the assessment developed for the 1998 and 2000 reporting cycles that was based on results of the 1994 IDNR stream use assessment. As stated in the assessment developed for the 1998 reporting cycle, the Class B(LR) uses were assessed as "partially supported" due to (1) relatively low fish community diversity (5 species from 3 families) for streams in the Des Moines Lobe subecoregion and (2) presence of less than a majority of the expected fish taxa (5 of 11) for streams in this subregion. As with the DNR stream use assessments for other streams in this portion of the upper Des Moines basin, rocky substrates and numerous snags hindered effective sampling (seining) of the fish community. Follow-up monitoring was recommended to better define the status of the aquatic communities and habitats and to determine the degree to which the Class B(LR) uses may be impaired. The field sheet indicates above average habitat quality, with no significant threats to the physical characteristics of this stream. Follow-up monitoring is still needed in this stream reach to determine the status of aquatic communities and habitats and to determine the degree to which the Class B(LR) uses may be impaired.
