The Utah Department of Natural Resources (DNR) has advised Union Pacific to proceed with its breach as planned, after Dec. 1. This recommendation comes after completing a series of simulations and models to study the impacts breaching the causeway will have on the Great Salt Lake.
Officials remain concerned about the Great Salt Lake’s low level. However, the department believes the most significant ecological concerns facing brine shrimp and migratory birds have been mitigated by waiting until December. The breach was originally scheduled for October.
DNR reached its decision after conducting a series of exercises and simulations to model the effect of the breach timing with the water and salt balances of the north and south arms and density-dependent flows through the causeway fill, breaches and culverts. The program has been developed as part of an inter-agency effort to advance the state’s modeling capabilities to better understand the impacts management actions have on the Great Salt Lake.
“We are committed to a healthy Great Salt Lake. We recognize the delay was an inconvenience to Union Pacific, but it was a necessary delay. We needed to better understand the impacts the timing of the breach would have on the lake’s ecosystem, brine shrimp industry and low water levels,” said Brian Cottam, director of the Utah Division of Forestry, Fire and State Lands. “While there will be impacts as a result of the breach, I believe the delay has helped us mitigate them and better protect the lake’s ecosystem.”
According to the modeling and analysis, DNR anticipates the south arm’s elevation will decrease by about 1 foot when the causeway is breached, which may cause it to reach a new historic low. The elevation of the north arm will also change. Modeling shows its elevation may increase by about 1 foot. Additionally, the salinity of the south arm is expected to increase by less than 1 percent.
In September, DNR and the Utah Department of Environmental Quality (DEQ) worked with the U.S. Army Corps of Engineers, Union Pacific Railroad and representatives from the brine shrimp industry to delay the project. The delay allowed state biologists, water experts and lake managers more time to assess the impacts breaching the causeway would have on water flow between the lake’s north and south arms.
Prior to the delay, biologists from the Utah Division of Wildlife Resources (DWR) expressed concern that the salinity of the south arm could increase to dangerous levels as higher saline water from the north arm mixed with the south. Too significant of an increase in salinity could harm the lake’s ecosystem, particularly brine shrimp and migrating birds.
The lake has reached a stage now where breaching the causeway will have relatively few, if any, impacts on brine shrimp and birds for the current year. Over half of the world’s eared grebes population migrates to the Great Salt Lake in late summer and feeds exclusively on brine shrimp. While here, the birds undergo a feather molt and become flightless. The lake’s brine shrimp population dies off every December as lake temperatures drop. Eared grebes continue their migration south once their food source is gone.
“Union Pacific’s willingness to delay the breach significantly helped avoid risk to about 5 million eared grebes at a critical and sensitive time,” said John Luft, Great Salt Lake ecosystem project manager. “Opening the causeway at this point in time shouldn’t affect the brine shrimp, or the grebes since the lake is entering a natural transition period.”
Next year’s brine shrimp population will hatch again in the spring. DNR believes they will acclimate to the slight change in salinity. However, the department will continue to have concerns with low lake levels and what impact it will have on the overall health of the ecosystem.
For more information about the Union Pacific railroad causeway and construction of its new 180-foot bridge and adjustable earthen control berm, visit 1https://www.up.com/aboutup/community/inside_track/causeway-6-14-206.