Spring Creek IA 02-WIN-846

Assessment Comments

Stream use assessment in Cerro Gordo County.

Basis for Assessment

Used a review of the field sheet from the October 1992 DNR stream use assessment in Cerro Gordo County to continue to assess support of the Class B(LR) as PS due to (1) relatively low fish community diversity (9 species from 2 families, with 8 of 9 species cyprinids), (2) presence of less than a majority of the expected fish taxa (5 of 11) for streams in the Iowan Surface subecoregion (47c), and (3) indications on field sheet of frequent channel alterations from channel straightening and removal of riparian vegetation.  Historical fish surveys in this stream reach suggest the possibility of a decline in the biological integrity of this stream.   A fish survey by Iowa State University (JRO-17-1981) in 1981 found 9 species (same as the 1992 SUA) but from 4 families; this survey was made with the same gear (4'X 15' (1/4" mesh) seine) as the 1992 DNR survey.   A more thorough sampling conducted by UHL in 1984 as part of a study of Calmus Creek (UHL Report 85-1) found a total of 17 species from 5 families in samplings with seines and electrofishers in May and August of 1984.   The relatively low diversity in the 1992 DNR stream use assessment may be due to sampling bias or to transient water quality conditions.   Regardless, follow-up monitoring is needed to better determine the status of the aquatic communities of this stream and to determine whether the Class B(LR) use are impaired.