Assessment Comments

Assessment remains based on results of a September 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, 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 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" (IR 3a) 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" (IR 3b) based on results of biological monitoring and habitat assessment conducted as part of the IDNR stream use assessment in September 1994.   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).   The assessment developed for the 2004 assessment/listing cycle is 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) aquatic life uses were assessed as "partially supported”  due to (1) presence of a relatively depauperate fish community (7 species from 2 families) for streams in the Des Moines Lobe subecoregion, (2) presence of less than a majority of the expected fish taxa (4 of 11) for streams in this subregion, and (3) indications on the field sheet of extensive channel alterations due to channelization and generally poor quality aquatic habitats.   Follow-up monitoring was recommended to determine the status of the aquatic communities and habitats of this stream and to determine the degree to which the Class B(LR) uses may be impaired.   Because these data are now considered too old (greater than five years) to accurately characterize current water quality conditions, the assessment category is changed from "monitored" (indicating an assessment with relatively high confidence) to "evaluated" (indicating an assessment with relatively low confidence).   Follow-up monitoring is 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.