Red Rock Reservoir IA 04-LDM-1017

Assessment Comments

Basis for Assessment

None of the 18 samples collected during summers of 96 & 97 exceeded the Class A primary contact rec.  WQ criterion of 200 fecal coliforms/100 ml (geometric mean=3 orgs /100 ml; max value=31 orgs/100 ml).   During the same period, only 1 of 54 samples collected during 18 sampling events at the three sites on North Overlook Beach exceeded the Class A WQ criterion (geometric means of 6, 7, & 7 orgs/100 ml).   At Whitebreast Beach 4 of 54 samples (7.4%) exceeded the Class A WQ criterion, with geometric means of 8, 9, & 6 orgs/100 ml at the three sites.   All data suggest full support of Class A uses.  None of the 32 samples collected from Oct 95 to Sep 97 exceeded Class B(WW) WQ criteria for conventional pollutants & ammonia (=FS).  Levels of pesticides in whole-fish composite samples of 3-yr old carp were well below 1/2 the respective FDA action levels (=FS of fish consumption uses).   Lake is noted for crappie, catfish, largemouth bass & white bass fishing in the March/April 1998 Iowa Conservationist.  Despite the apparent support of all designated uses, this lake receives high silt loads from its watershed, and the ACOE has had to raise the level of the conservation pool of the reservoir in in response.   Thus consider overall support of uses as FST.