OOS 49-6
The influence of diking and diking modifications on flow and salinity in Utah's Great Salt Lake
The Great Salt Lake is one of Utah’s most recognizable features, generating approximately $1.3 billion in Utah’s gross domestic product, supporting a highly productive food web, and providing habitat for millions of migratory birds. In 1959, Union Pacific Railroad built a solid-fill railroad causeway across the Great Salt Lake, influencing the flow of water and salt in the lake, so that the south bay of the Great Salt Lake receives the majority of inflow, is less saline, and has a higher lake elevation. Open culverts in the causeway have subsided and recently been filled, effectively separating the north and south arms of the lake. A trapezoidal bridge is proposed for the existing causeway to increase flow and salinity across the lake. However, little is known regarding what effect this change would have on local industry and ecosystem dynamics. Large changes to lake level and salinity could be costly in terms of reduced industry, increased pumping to protect existing infrastructure, and may threaten the fragile and unique habitat provided by the Great Salt Lake. Likely changes to Great Salt Lake elevation and salinity from Union Pacific’s solid fill causeway are estimated using a mass balance model of the Great Salt Lake.
Results/Conclusions
Results describe lake elevations and salinities with the historical causeway, the present causeway with filled culverts, and proposed bridge designs. Gated dikes between the north and south arms have been identified as a tool to manage water and salt flow, and maintain ecosystems and industry of the Great Salt Lake. Other terminal lakes worldwide have been altered by solid-fill causeways or substantial flow modifications, including Iran’s Lake Urmia and California’s Owens and Mono Lakes. Flow modifications are compared among terminal lake systems to identify common problems and highlight promising solutions to maintain unique terminal lake ecosystems.