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Show actions will be evaluated, is the degree to which beneficial uses of sovereign land are judged to be impaired or enhanced, against a backdrop of preservation of most of GSL as a natural body of saline water. A natural body of saline water is defined as water with salinity ( average of the entire water column) within the range of salinity variation over the last 150 years. This is the lake's historical range. In choosing among alternatives the fundamental concern is not the particular economic impacts to a specific industry, company or activity. It is not the relative advantages of companies competing with each other. It is not to afford relief to south arm industries at the expense of north arm industries, nor to protect any special advantage of north arm industries against the complaints of south arm industries. The fundamental parameter is the public interest. The public interest is statewide, and in some respects the lake serves national and international interests. Protection of the lake's ecology will serve the public interest. For the first time on record the trend for salinity in the south arm of the lake is heading outside the historical range. This is a consequence of human disruption in the form of the northern railroad causeway and WDPP. In DNR's judgement salinity levels outside historical variation behind project- specific dikes and impoundments are acceptable because the change in salinity is the desired effect. The south arm, however, is too much of the lake to allow it to exceed historical salinity variation. DNR has concluded that the permeability of the northern railroad causeway has decreased. ( See Appendix I.) Prior to the 1980s high lake level, the causeway fill provided 70 percent of the brine interchange, the culverts 30 percent. Compaction of the fill, introduction of organic and inorganic fine material over time and the addition of fill required to keep the causeway above rising water in the 1980s has significantly decreased permeability. Removal of some 600 million tons of salt from GSL by WDPP has contributed to the south arm salinity concern. Initial results of USGS and DWRe modeling ( See Appendix H.) shows that approximately 80 percent of the salinity difference between the 1980s to the present is attributable to decreased permeability of the causeway. The remaining 20 percent of the difference is attributable to WDPP. The salinity concern may be alleviated to some degree by operating WDPP through a full cycle to return some of the salt deposited in the west desert, but in the absence of a flooding emergency, WDPP modification, startup and operational costs are prohibitive. The most cost effective, long- term remedy is causeway modification to increase the exchange of brine. To compensate for the loss of salt to the West Pond and decreased causeway permeability, the causeway breach will be deepened about four feet to its original design depth of about 4195 feet. Structural integrity of the bridge will not be affected by this excavation. The culverts will be kept clean by the railroad. The effect of the causeway modification on south arm salinity will be monitored. The potential for additional openings in the causeway will be studied in the event DNR determines that open culverts and a deepened breach are not sufficient to keep south arm salinity within its historical range. As noted in the ecosystem section, lack of full scientific certainty should not be used as a reason not to initiate measures to prevent environmental degradation. A precautionary 237 |
