Middle Raccoon River IA 04-RAC-1191

Assessment Comments

Assessment remains based on surveys by the IDNR Fisheries Management Section in 2000 and and IDNR Fisheries Research Section in 2002: FIBI = 44 (fair). FIBI BIC = 36.

Basis for Assessment

SUMMARY:  The Class A1 (primary contact recreation) uses remain "not assessed."  The Class B(WW1) aquatic life uses remain assessed (evaluated) as "fully supported" based on results of fish surveys conducted by (1) the IDNR Fisheries Management Section (Boone) in 2000 and (2) the IDNR Fisheries Research Section in 2002.   Fish consumption uses remain "not assessed."  

EXPLANATION:  The Class A1 (primary contact recreation) uses remain "not assessed" due to the lack of water quality information for this segment upon which to base an assessment.  

This assessment of the Class B(WW1) aquatic life uses remains partially based on data collected in 2002 as part of a DNR Fisheries stream sampling project: Manchester research station.   A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the Fisheries sampling data.   The biological metrics are based on the numbers and types of fish species that were collected in the stream sampling reach.   The biological metrics were combined to make a fish community index of biotic integrity (FIBI).   The index ranks the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum).   The 2002 evaluated FIBI was 44 (fair).   The aquatic life use support was assessed (evaluated) as Fully Supporting (=FS), based on a comparison of the FIBI score with biological impairment criteria (BIC) established for previous Section 305(b) reports.   The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2004.   The FIBI BIC for this ecoregion is 36.

However, 2000 information from the IDNR Fisheries Bureau suggests that problems with growth and reproduction of smallmouth bass (see previous assessments).   Habitat quality is still seen as a key factor, but water quality--specifically, high levels of ammonia-nitrogen--may also be impacting the smallmouth bass populations in this segment.   Due, however, to the lack of routine, ambient monitoring in the Middle Raccoon River, the data to support this hypothesis do not exist.   Nonetheless, the continuing problems with the smallmouth bass population in this segment suggests that the Class B(WW1) uses should be assessed as "fully supporting / threatened" but due to changes in methodology, that assessment category is no longer available and IDNR feels that after analyzing all the data, the segment is more "fully supporting" the aquatic life uses than "partially supporting" these uses.

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this river segment.