A Lake Divided

Many people don't realize that the Great Salt Lake is a divided body of water, with each half operating almost independently from the other.

This is not the natural state of affairs.  For centurys, water in the Great Salt Lake could move freely and without restriction.  Then, in the late 1950s, the railroad built an earthen causeway across the lake.  Although a couple of culverts were added to enable some mixing between the two haves, they have remained only loosely connected for many years and their chemical composition is dramatically different.  Most of the freshwater inflow to the Great Salt Lake enters the south half, so the salinity is lower (typically 9–12%) than found in the north half (typically ~28%).  This leads to differences in algeal and bacterial and water color between the two halves that can clearly be seen from space and the ground.

The Great Salt Lake from space.  Source: NASA S135-E-006466.

The Salt Lake Tribune reports this morning that the two culverts have been in a state of decay for many years.  One needed to be plugged last year, the other is currently failing and needs to be plugged for the railroad to continue operations.  This will fully divide the lake once again.  There are discussions about putting in a 180 ft bridge (yet to be designed) to reenable some flow between the two halves.

How to deal with this causeway issue is a remarkably complex question.  Lake salinity will be strongly influenced by how much water can flow between the two halves, with direct ecological and economic consequences.  Thus, I expect this will be a contentious issue and a remarkable case study in the management (or mismanagement) of coupled human and natural systems.