Purgatory Creek IA 04-RAC-1159

Assessment Comments

Stream use assessment.

Basis for Assessment

Used a review of the field sheet from the July 1992 DNR stream use assessment to upgrade the assessment of support of the Class B(LR) aquatic life uses from PS to FST due to (1) presence of approximately the minimum diversity of a fish community (8 species from 2 families) for headwater streams in the Des Moines Lobe subecoregion, despite difficulty in sampling (seining), (2) presence of a majority of the expected fish taxa (7 of 11) for streams in this subecoregion (no centrarchids, ictalurids, or darters present), (3) sampling was conducted less than 2 miles from the Class B(LR)/general use boundary of the nearly 18-mile Class B(LR) segment and notes on field sheet indicated that the downstream sites "had somewhat better habitat" with "visibile riffles."  Notes also suggest that the site sampled may have been under the influence of a beaver dam.   Field sheet indicates that the stream is threatened by extensive channel alterations, including channelization and over-pasturing of the riparian area with siltation also a problem.   Additonal assessments are needed on this stream to better define the status of the aquatic communities and habitats.