Union Pacific has agreed to breach the causeway to replace two culverts that once allowed water to flow beneath it. Those culverts were filled beginning in 2011 because the culverts had sunk about 20 feet into the lake and were unstable.
When complete, the breach will be traversed by a bridge to facilitate rail traffic across the lake.
Earlier this year, however, it became apparent that because of increasingly low water levels in the lake, opening the breach this fall could have unintended consequences.
Since the loss of the culverts, the majority of the water that goes into the Great Salt Lake has been unable to reach the northern arm of the lake. Consequently, the level of the lake is higher on the southern side than on the northern side.
When the breach is opened, some of that extra water will flow onto the northern side, causing the water level on the southern side to drop an estimated 1.5 feet.
Should that happen now, members of the Great Salt Lake Yacht Club worried that water levels in the Great Salt Lake Marina would drop so low that the rescue boats that deploy from that location would be unable to access the lake.
Janet Robins, the Great Salt Lake Yacht Club commodore, said the deepest point of the marina is about 5 feet deep, and water depth at the mouth of the marina is 3.3 feet. Even the smallest of the rescue boats need at least 2.5 feet of water in order to operate, she said.
Robins said search and rescue crews have experienced difficulty in accessing the lake. The nicest, largest rescue boat at their disposal was pulled out of the marina two months ago, she said, when water levels dropped below what was required for the facility's operation. An older, smaller boat remained available, she said, until operating in shallow conditions caused its engine to fail.
"The boats can get in and out," she said, "but it's doing some serious damage."
State officials considered emergency dredging for the marina, but with the delay of the breach, those contingency plans are no longer necessary, said Nathan Schwebach, spokesman for the Utah Department of Natural Resources.
The state plans to dredge the marina early next year, he said, to remove silt that has accumulated.
While a focal point of the discussion, the search and rescue boats, which deploy an average of about 110 times per year, weren't the only concern that led to the delay of the breach.
Because the northern arm has been cut off from most of the freshwater inflow for the Great Salt Lake, the northern end of the lake has become much more saline than the southern end. And with water levels at or near record lows, many experts worried that an undiluted influx of saltwater into the south arm could kill off large quantities of brine shrimp in the lake. That, in turn, could cut into next year's harvest for the lake's brine shrimp industry, and could reduce the amount of food available for waterfowl this winter.
According to the Utah Division of Wildlife Resources, brine shrimp serve as the primary source of food for millions of birds that spend some part of the winter on the Great Salt Lake. For example, 4 million to 5 million eared grebes — more than half the entire population of that species — winters at the Great Salt Lake.