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Show the point that return flow through the breach opening ceased. From that time until 1999, flow through the breach opening was mainly south- to- north which has resulted in a decrease in south- arm salt load and an increase in the north arm load. During some summer months, salt has precipitated on the floor of the north arm where it will remain until conditions change and the north- arm salinity decreases. Early in 1999 there was very little bidirectional flow observed moving through the breach. Later in the year, however, as the level of the lake rose and the head differential across the causeway decreased, deep north- to- south return flow was observed within the breach opening. West Desert Pumping The second emergency flood- control measure was implemented after the lake continued to rise, following the opening of the breach in the northern railroad causeway. This measure involved pumping water from the north arm of the lake out into the West Desert to increase the total evaporative surface area and to physically remove water from the lake. To accomplish this, three giant pumps were installed near Hogup Ridge ( about 12 miles west of Lakeside). The water was pumped from Hogup Ridge by way of a 4.1- mile canal to the West Desert where it was impounded in a 320,000- acre pond, contained by dikes. ( See Figure 6.) WDPP was successful in helping to lower the level of the lake from 1987 to 1989, but in the process 600 million tons of crystalline salt, representing 10- 14 percent of the total salt- load of the lake, were precipitated and/ or deposited on the pond floor when the project was suspended in 1989. ( See discussion on " Operating Consequences and Constraints," page 34.) Ion Concentrations in Lake Brines Unlike the lake's variable salinity ( total grams of dissolved salt per liter of solution), its chemical composition ( ratio of various dissolved ions to one another) is relatively constant throughout the north and south arms of the lake, and within Bear River and Farmington Bays. This chemical consistency exists because: ( 1) chemical homogeneity existed throughout the lake prior to the construction of the railroad and other causeways and ( 2) continual brine mixing, however limited, occurs among all portions of the lake. Slight, long- term changes in ion- ratios have been observed throughout the lake as a whole. Table 2 gives an average chemical composition of the dissolved salts in GSL waters on a dry- weight- percent basis, as contained in the UGS- GSL database. The compositions of typical ocean and Dead Sea waters are given for comparisons. 48 |