Assessment Comments
Assessment remains based on results of a November 1994 IDNR stream use assessment.
Basis for Assessment
SUMMARY: The Class B(LR) aquatic life uses remain assessed 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 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 2006 Integrated Report (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) 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 only 3 of the 11 expected fish taxa for streams in this subregion. The relatively poor results for sampling of the aquatic community is likely due to the abundance of rocky substrates and snags in this stream. Nonetheless, the low diversity and lack of environmentally sensitive species suggests that follow-up monitoring is needed to better determine the status of the aquatic communities and to determine the degree to which the Class B(LR) uses may be impaired. Field sheet indicates no significant impacts to the physical characteristics of this stream. 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.
