Water Quality Conditions in the Cahaba River and Likely Pollutant Sources Robert E. Pitt, Ph.D., P.E., DEE Department of Civil and Environmental Engineering University of Alabama at Birmingham August 9, 2000 Introduction .................................................................................................................................................................................... 2 Water Quality Criteria .................................................................................................................................................................... 3 Water Quality Criteria for the Protection of Fish and Wildlife............................................................................................ 6 Dissolved Oxygen................................................................................................................................................................. 6 Bacteria ................................................................................................................................................................................... 9 Hardness................................................................................................................................................................................. 9 Ammonia............................................................................................................................................................................... 10 Nitrates.................................................................................................................................................................................. 13 pH.......................................................................................................................................................................................... 14 Phosphate............................................................................................................................................................................. 16 Dissolved Solids, Conductivity, and Chlorides.............................................................................................................. 18 Temperature ......................................................................................................................................................................... 19 Suspended Solids and Turbidity ...................................................................................................................................... 23 Heavy Metals ....................................................................................................................................................................... 25 Water Quality Criteria for the Protection of Human Health............................................................................................... 26 Bacteria ................................................................................................................................................................................. 26 Hardness............................................................................................................................................................................... 27 Nitrates.................................................................................................................................................................................. 27 Dissolved Solids, Conductivity, and Chlorides.............................................................................................................. 28 Toxic Organics ..................................................................................................................................................................... 29 Heavy Metals ....................................................................................................................................................................... 29 Historical Observed Concentrations of Pollutants in the Cahaba River (1970-1990)......................................................... 30 Upper Cahaba River Water Quality Conditions.................................................................................................................. 30 Temperature ......................................................................................................................................................................... 31 pH.......................................................................................................................................................................................... 34 Hardness............................................................................................................................................................................... 35 Dissolved Oxygen and Biochemical Oxygen Demand................................................................................................... 35 Turbidity and Suspended Solids ...................................................................................................................................... 38 Total Dissolved Solids, Chlorides, and Conductivity ................................................................................................... 39 Fecal Coliform Bacteria ....................................................................................................................................................... 39 Nitrate Nitrogen................................................................................................................................................................... 40 Ammonia and Kjeldahl Nitrogen....................................................................................................................................... 40 Phosphate............................................................................................................................................................................. 42 Arsenic.................................................................................................................................................................................. 43 Cadmium............................................................................................................................................................................... 43 Chromium.............................................................................................................................................................................. 44 1 Copper................................................................................................................................................................................... 44 Iron ........................................................................................................................................................................................ 45 Lead....................................................................................................................................................................................... 45 Mercury ................................................................................................................................................................................ 47 Zinc........................................................................................................................................................................................ 47 Organic Toxicants ............................................................................................................................................................... 48 Water Quality Conditions at Mid-Watershed Locations in the Cahaba River............................................................... 48 Recent Water Quality Conditions Observed in the Upper Cahaba River............................................................................ 54 Methodology............................................................................................................................................................................ 55 Results ....................................................................................................................................................................................... 56 Nutrients ............................................................................................................................................................................... 62 Pesticides.............................................................................................................................................................................. 65 Turbidity............................................................................................................................................................................... 69 Allowable Wastewater Discharges ........................................................................................................................................... 70 Critical Low Flows in the Cahaba River................................................................................................................................ 70 Water Quality During Critical Low Flow Conditions.......................................................................................................... 71 Allowable Discharge Limits...................................................................................................................................................