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Show amounts that result in concentrations greater than those already present in the lake. The nitrogen and phosphorus in sewage effluents are not regulated by DWQ unless it can be shown that they are causing an impairment to the beneficial use in the receiving waters. Some question if this is an effective policy. Dischargers are regulated by state and federal effluent limitations for total suspended solids ( TSS), biochemical oxygen demand, coliforms, pH and some metals. A public notice process is followed to allow comment on any concerns. Except for sewage treatment facilities, most facilities do not directly discharge into the lake and a mixing zone is allowed most cases. Permitted Discharges to Great Salt Lake Permitted discharges to GSL fall into three major classifications; municipal wastewater treatment facility discharges, mineral extraction facility discharges and other industrial facility discharges. Wastewater treatment facilities typically treat high levels of organic materials, which generate high biological oxygen demand ( BOD) and bacteria. Nutrient levels ( nitrogen and phosphorus) are also exceedingly high in these wastewater discharges and can lead to eutrophication. Mineral ( salt) extraction industries produce bitterns or residual water from their solar evaporation ponds. These facilities withdraw water from GSL and then use solar evaporation to precipitate various salts from this water. Specific effluent guidelines and standards are applicable to discharges from salt extraction industries. The requirement is that the effluent contain only materials originally present in the intake water. Industrial discharges include effluent from the Kennecott Utah Copper ( KUC) concentration and smelting operations and from oil refineries located in the North Salt Lake area. The copper mining and refining operations produce heavy metals, total and suspended solids and petroleum. Discharges from oil refineries have limitations on mass BOD, TSS, oil and grease, phenolic compounds, ammonia, sulfide and chromium. A listing of existing permits for discharges to GSL and its near- lake tributaries is in Appendix A. Potential for Changes to Lake Water Quality The overall quality of GSL water is good. From a biological standpoint, the lake's aquatic biological system is described as nitrogen- limited. Nitrates and phosphates, which are usually characterized as " pollutants" in freshwater aquatic systems, are almost completely consumed by lake organisms and do not pose problems in the open water of GSL that they otherwise can. In wetlands adjacent to the lake, nutrient loading may be adversely affecting buffering capability. Other factors on and near the lake, such as the wetland- marsh complexes on the east shore of the lake, are thought to be beneficial in " treating" non- point sources of potential pollution before they reach the lake. Some potential causes for water quality degradation are emergency spills and unpermitted discharges on and near the lake, possible contaminants in lake- bottom sediments and pollutants from non- point sources near the lake and entering tributaries. 55 |
