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Show 75 * For additional information concerning the climatology and hydrology of the Great Salt Lake, see Great Salt Lake Climate and Hydrologic System, prepared by Utah Division of Water Resources, Department of Natural Resources, December 1974. THE CAUSEWAY AND THE GREAT SALT LAKE HYDROLOGY Prior to completion of the Southern Pacific Railroad causeway in 1959, the total dissolved solid load and the chemical composition of the brine were controlled primarily by changes in volume resulting from natural processes. However, due to the construction of the causeway dividing the Lake into two separate arms the South Arm has been as much as 2.05 feet higher than the North Arm during high inflows, and brine concentration of the South Arm has decreased while that of the North Arm has increased. As shown in Figure 12, during the peak period in 1974, the elevation of the South Arm was found to be 2.05 feet higher than that of the North Arm due to the restricted flow of water through the causeway. Brine flows both directions through the causeway with more dilute brine moving northward from the South Arm through the upper part of the causeway and denser brine from the North Arm moving southward through the lower part of the causeway. As a result, the post- causeway chemistry of the Lake is a function of the interchange of dissolved solids through the causeway and changes in the salt crust and volume of the Lake. In addition to the raised elevation of the South Arm which dilutes the concentration of the brines by increasing volume, the South Arm currently receives more than 95 percent of the fresh water surface inflow that previously fed the entire Lake, further diluting the South Arm brines. |
