Record Low Water Surface Elevations at Great Salt Lake, Utah, 2021-2022

Abstract

The United States Geological Survey (USGS) operates two long-term water-surface elevation (WSE) gages on Great Salt Lake, Utah, one north of the Union Pacific Railroad causeway in the historic Little Valley Boat Harbor (Saline gage), and one south of the causeway in the harbor at Great Salt Lake State Park (Saltair gage). From September 28 to December 15, 2022, lake levels were too low in the harbor for the Saltair gage to operate and WSE data was measured at the South Causeway gage, a relatively new gaging station (installed in 2020) located immediately south of the causeway. Data collected at the South Causeway gage were used to estimate the daily mean WSE record for the Saltair gage for the period it was shut down, preserving the continuity of the 175-year WSE record that is associated with this gage. The long-standing historic low daily mean WSE measured at the Saltair gage on October 15, 1963 (4,191.35 feet, relative to the National Geodetic Vertical Datum of 1929 (NGVD29)) was broken on July 21, 2021. Seasonal lake-level declines Geodetic Vertical Datum of 1929 (NGVD29)) was broken on July 21, 2021. Seasonal lake-level declines from July 2021 to October 2021 and April 2022 to early November 2022 resulted in a new historic low daily mean WSE of 4,188.5 feet NGVD29, measured during several days during November 2022 at the South Causeway gage. The same value is also the new historic low daily mean WSE for the Saline gage and was measured during several days in November and December 2022 (the previous historic low of 4,188.98 feet NGVD29 was measured in September and October 2016 and was related to closure of two railroad causeway culverts). USGS also operates streamgages on major surface-water inflows including the Bear River, Weber River, Jordan River, and Surplus Canal. The combined annual discharge measured at these gages in water years 2021 and 2022 was 0.704 and 0.743 million acre-feet, respectively, which is less than half of the combined median annual discharge (1.57 million acre-feet) based on the period of record for each gage.