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Show The UGMS and the USGS have conducted preliminary investigations of the circulation patterns within Great Salt Lake. Figure 9 illustrates the general circulation patterns within the lake since the construction of the railroad causeway. The UGMS and the USGS are continuing to gather data which will provide further information on circulation patterns and the distribution of dissolved solids within the lake. Lin et al. ( 1972) report on data collected during the summer of 1972. Detailed vertical profiles of temperature, dissolved oxygen, conductivity and pH values were measured among 17 buoy stations installed at the south end of the lake. Lin also found a deep and more dense brine underlying portions of the south end brine. It was pointed out that the collection of such detailed data for the first time allowed the observation of the very subtle characteristics of the lake water, and that more extensive study of the same type will lead to answers to questions such as the occurrence of deep brine ( Figure 8). The salt distribution problem which resulted from the construction of the Southern Pacific Transportation Company's causeway across Great Salt Lake prompted studies of the effects which the causeway is having on the lake and possible solutions to the problem. The net movement of salt to the northern arm was reported in a brief article by Adams ( 1964). Because of the decreasing density of the brine in the southern arm, the salt extraction companies located there became deeply concerned with finding the cause and a solution to the problem. Clyde, Criddle, and Woodward, Inc., Consulting Engineering Firm, was retained by several salt companies to establish the fundamental reasons for the changes in salt content. The firm's 1970 report links the density change to the railroad causeway and concluded that an opening in the causeway 1500 feet long would be required to restore pre- causeway conditions. This conclusion was based on an assumption of a small flow through the causeway fill. A reconnaissance study by Madison ( 1970) indicated that a net load of about 0.30 billion tons of dis- i solved solids had moved from the south to the north part of the lake from 1963 to 1969 due to effects of 1 the causeway. Madison recommended that a detailed study be made to enable predictions of long- term effects of the causeway. During 1970- 72, the USGS and the Utah Geological and Mineralogical Survey carried out an investigation based principally on Madison's recommendations. The purpose of the study was to determine the net movement of dissolved- solids through the causeway during 1971- 1972 water year, to predict salt load movements during rising and falling lake stagss for the existing causeway through the use of a simulation model, and to predict the possible effects of various culvert widths on load movement. The study gives culvert widths required to establish various conditions in the relation between the north and south arm brines and recommends that the results be verified with additional data. The study also recognizes that the economic and social impacts must be considered in any decision to alter the widths of the present causeway culverts. Two additional models of flow through the causeway have been developed. Lin and Lee ( 1972) developed a Hele- Shaw model of seepage flow through the causeway and suggest that the model study, when coupled with field investigations, should provide all the information needed to assess the impacts of the causeway. Cheng and Hu have submitted a report for publication in the Journal of the Hydraulics Division of the American Society of Civil Engineers in which they present a mathematical model of a two- fluid flow system through a homogeneous porous media. Results of the numerical solution are correlated with that of a Hele- Shaw experiment. The USGS in Salt Lake City will incorporate the causeway model they developed into a simulation mo- ; del of Great Salt Lake which is currently under development. The model which the USGS is developing will divide the lake into three or four units and assume complete horizontal mixing within each unit, but will not deal with vertical stratification. The model will be used to study the effects produced by changes in the inflow and will also analyze the various diking schemes proposed for the lake. Life species which inhabit the waters of Great Salt ILake are few due to the harsh environment created by the high brine concentration. Organisms include bacteria, several species of green and blue- green algae, several species of protozoans, one species of crustacean ( brme- shrirnp), and two species of brine fly. In addition, forms typical of fresh water are found in the lake on occasion, but it is felt that these are extraneous forms which have been washed in from freshwater bays and probably survive for only short periods of time. Most of the biological work on the lake was done in the 1930s. Flowers ( 1934) found four species of blue green algae and two species of green algae. Kirk- pa trick ( 1934) cultured lake waters in the laboratory in an attempt to separate native from extraneous algal forms. She reported 13 species of algae as well as some protozoans. Patrick ( 1936) identified 24 genera and 62 species of diatoms from lake bottom samples. Eardley ( 1938) reviewed the literature on life in the lake and listed the brine shrimp, three flies, five pro- 31 |