Black Hawk Lake IA 04-RAC-1134

Assessment Comments

Monitored in 1990 by ISU for the Clean Lakes Classification study (1994); monitored for 1992 RAFT.

Basis for Assessment

Used the assess support of the Class A A primary contact recreation uses (=FST) and the Class B(LW) aquatic life uses (=FST) developed for the 1996 report.  Support of fish consumption uses remains FS based on results of the 1992 fish tissue (RAFT) sampling.   These assessments of use support, as well as the water quality trend for the lake ("improving") were reviewed in 1998 by the DNR Fisheries Bureau.   Data for fecal coliform bacteria collected at two locations in the lake from 1993 to 1995 suggest relatively low levels and full support of Class A primary contact recreation uses.  In the 15 samples collected during summers of 1993, 94, and 95 at two locations, only two samples at each location exceeded the Class A WQ criterion of 200 organisms per 100 ml.  Based on Section 305(b) assessment procedures, both locations suggest full support of Class A uses (i.e., geometric means (32 & 21) are less than 200 orgs/100 ml and the percentages of samples > 400 orgs/100 ml (6% and 7%) are less than 10%).  According to the March/April 1998 Iowa Conservationist, this lake supports good populations of walleye, bullheads, yellow bass, and channel catfish.