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USGS update: north/south connectivity, discharge trends and salinity patchiness at Great Salt Lake
Summary
USGS scientists reported recent increases in lake elevation since fall but continuing differences between north and south arms; flow through the causeway has oscillated with seasonal discharge directions, and Lakeside Reach shows very high local salinity. Monitoring efforts to produce continuous discharge data are underway.
Christine Ramsey of the U.S. Geological Survey presented hydrology and salinity monitoring across the Great Salt Lake, including elevation changes, causeway flows and site-specific salinity measurements.
Ramsey said lake elevation rose about 1.2–1.4 feet from seasonal lows in the north and south arms but the south arm remains lower relative to last year. She reviewed time series that show an elevation difference between arms narrowed beginning last fall and is currently about 0.9 foot. Causeway flows have been bi-directional; the team observed intermittent north-to-south flow after the causeway was raised in February 2023 and intermittent south-to-north flows during late 2023 and early 2024. Recent instantaneous discharge estimates at midreach were in the 1,000–1,100 cubic-feet-per-second range, typically south to north, with smaller, episodic north-to-south flows verified by water-quality sampling.
At the Lakeside Reach (west side of the causeway) the group reported continuous discharge measurements showing seasonal variability and a recent north-to-south contribution from west-side canal inflows. Local salinity at Lakeside was measured at very high values (e.g., 44 g/L in one recent check); other sites measured February surface salinities ranging from about 12 g/L to 256 g/L depending on location and source (north-south flow contributions were noted as chemically distinct).
Ramsey described ongoing efforts to build continuous-discharge estimates at several sites. Those efforts include remote cameras for site monitoring, surface-water velocity sensors placed on both east and west openings of breach channels and a collaboration with a university modeling group to develop continuous-discharge products. She highlighted that monitoring is difficult in complex channels like the Bear River outflow and that monthly field measurements plus telemetry (camera images and velocity sensors) are part of the strategy to produce more reliable continuous records.
Ramsey and colleagues cautioned that localized inputs (canal flow, breakup or flushing events) can change salinity signatures at particular sites; they urged more targeted sampling to verify chemistry at sites with unusually high or anomalous salinities. No regulatory actions were proposed — this was a technical monitoring update.
