This is an archived article that was published on sltrib.com in 2016, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

The Union Pacific Railroad this week began breaching the 20-mile causeway that bisects the Great Salt Lake, allowing the waters from the lake's north arm and south arm to mix.

The causeway was constructed in 1959 with two 15-foot culverts that allowed waters to circulate. Still, the two arms of the lake began to look very different over time, to the detriment of the ecosystem and industries that rely on the lake. The north arm took on a reddish hue and became much saltier than the south arm, which is fed by fresh waters from the Bear, Weber and Provo rivers.

After the aging culverts began collapsing, Union Pacific in 2011 began filling them in to ensure the structural integrity of the causeway, which conveys a railroad line across the Great Salt Lake.

The railroad agreed to open a breach this fall, which will eventually be spanned by a bridge.

State models suggest the breach will cause the water level of the south end to drop by about a foot, and increase its salinity by about 1 percent.