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Railroad causeway

Published October 3, 2012 10:41 pm

Equalize salt in the Great Salt Lake
This is an archived article that was published on sltrib.com in 2012, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

Union Pacific Railroad's causeway across the Great Salt Lake acts as a dam that isolates the northern arm of the lake from the southern. As a result, the northern arm is saltier, and this has broad impacts not only on the lake's ecology but its extraction industries. It would not be unreasonable, then, for government to require the railroad to monitor the effects of the causeway on salt concentrations in the lake.

That said, the railroad is not the only industry with a duck on this pond. If a monitoring system is a good idea, then other commercial interests on the lake should help pay for it as well. Brine shrimpers and the magnesium and sulphate of potash industries would be logical candidates to contribute.

The monitoring issue has risen because the causeway has settled, up to 20 feet in some places. To deal with that emergency, the railroad has asked permission of the U.S. Army Corps of Engineers to plug two culverts and build a new bridge. The culverts allow water to circulate between the two arms of the lake, but one is cracked and in danger of failing. The corps has approved emergency repairs but also has required the railroad to develop plans to monitor the impact of the improvements and ensure that salt circulates freely between the two arms of the lake. The railroad is objecting to these conditions.

Settling of the causeway is nothing new. In fact, it has plagued the route, known as the Lucin Cutoff, since it was built by the Southern Pacific in 1902 and 1903. The original causeway was constructed on timber pilings driven deep into the soft sediments that form the lake bed. Rock and soil then were added between the pilings. However, the weight of that fill material often squeezed the sediments outward from below the causeway, creating huge upwellings of the lake bed as the track sank, in turn causing derailments of heavy locomotives, the same risk the railroad must mitigate today.

Until the late 1950s, a 13-mile segment of the original causeway remained on wooden trestle that allowed water to flow freely beneath it. Beginning in 1957, the railroad built a new segment of earthen causeway parallel to the old trestle, which was subsequently removed. The new segment included two large culverts, but the comparative salinity of the two arms of the lake began to change. Most fresh water enters the lake's southern arm, and without adequate circulation through the causeway, salt has become more concentrated in the northern arm.

The salinity issues are not new. But a solution that could improve the circulation of water and salt between the two arms of the lake would be a welcome innovation.