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Show The lake should be restored to a close approximation of a natural condition. This would provide for natural lake level fluctuation and improve brine distribution. All users should adjust to natural changes rather than dealing with human- made changes. The goal should be for the lake to have a balanced ecosystem. There is a net movement of salt from south- to- north during the times that the lake is rising, but that the opposite is true during times of declining lake levels. IMC further points out that the decline in potassium values in the north arm brines has occurred at a greater rate than changes in the north arm's overall salinity. Between 1970 and 1972, a study by Waddell and Bolke ( UGMS Water- Resources Bulletin 18, 1973) reports that "... the discharge through the fill comprises more than 80 percent of the total flow through the causeway." It is suggested that this condition may have lasted until the SPRR tracks were raised during the 1980s flooding, but there are no studies to confirm this. To keep ahead of the rapidly rising waters, the tracks and fills had to be quickly raised 6- 10 feet to keep a bare minimum free board of two feet. During peak production the track was raised an average of one- half to one foot- file per day with the use of on track hydraulic liner/ lifters ( shifter/ lifters), tampers and off- track backhoes. The northern railroad causeway was raised using crushed ballast from the Lakeside Quarry and quarry- run rock, as noted in a SPRR report. Over 90 percent of the fill material was quarry- run rock from the Lakeside Quarry and the remainder was pit- run sand and silt from a track- side pit located at Promontory. The causeway's permeability has been decreased by the addition of this material, but to what degree is not known. Ongoing modeling by USGS is being done in an attempt to estimate its present- day permeability. Cleaning the culverts will have an impact on the salinity difference between the south and north arms depending upon a number of hydrologic parameters such as lake elevation, water densities and the head differential between the north and south arms. The overall effect is unknown. Deepening the breach in conjunction with the construction of a breach- depth channel into the south arm, would be another option to equalize the salinity. Other alternatives also exist. These can be evaluated in the USGS model before costly actions are taken. Salinity, as the term is being used here, means that amount of salt ( grams) that is contained in a quantity ( Liter) of brine, thus ( g/ L). It can also be expressed in terms of the percent of salt in the brine. The flow of water through the causeway was a concern when the original right- of- way was granted but there is no enforceable provision in the document specific to permeability. The railroad has acknowledged a responsibility to keep the culverts open. The railroad has been apprised of salinity concerns and is willing to continue working with DNR to address the issues. Historical experience suggests that when there was greater mixing of north and south arm brines, brine shrimp populations were more robust. The lake is dynamic in that it fluctuates and thus its salinity falls and rises accordingly. Brine shrimp may live in brines of up to 20 percent salt. Prior to the construction of the 287 |