Great Salt Lake Elevations

Science Center Objects

Great Salt Lake Elevations

The United States Geological Survey (USGS) has been collecting water-surface-elevation data from Great Salt Lake since 1875 and continuously since October 1902. The north part of the lake has been monitored since April 1966.

Get current and historical lake levels here.

Great Salt Lake as viewed from earth's orbit

Great Salt Lake as viewed from earth's orbit - Photosynthetic sulfur bacteria color the water a reddish-purple in the high-salinity north arm's, Gunnison Bay. Gilbert Bay in the southern arm receives all of the fresh-water infows to the lake and is naturally blue-green. The location of the railroad causeway can be identified by the color change. (Public domain.)

 

Great Salt Lake gage at Saltair Boat Harbor

Great Salt Lake gage at Saltair Beach State Park used to determine elevation of water in south arm (Public domain.)

Great Salt Lake differs in elevation between the south and north parts. The Union Pacific Railroad causeway divides the lake into two parts. The water-surface elevation of the south part of the lake is usually higher than that of the north part because most of the inflow to the lake is in the south part.

Therefore, two gages are used to monitor the different lake levels. The gage at the boat harbor at Saltair Beach State Park measures the elevation of the water in the south part. It has been operated since October 1938. The gage at the Little Valley Boat Harbor, northwest of Saline, Utah meaures the elevation of the water in the north part. It has been operated since April 1966. A third gage was operated at Promontory Point (north end of the south part) from October 1986 to September 1999.

Great Salt Lake gage near Saline, Utah

Gage on Great Salt Lake near Saline, Utah, used to determine elevation of water in north arm of lake (Public domain.)

 

 

These gages record the elevation of the lake every 15 minutes and the data are transmitted to a satellite every 4 hours. These data are captured by a satellite downlink and entered into the USGS computer system. Mean daily elevations are computed and made available to the public. Wind and seiche effects may cause substantial short-term changes in elevations, which are not shown in the mean daily values. 

Note: Discrepancies in the lake elevations led to revisions of the base datum and the water-level record from April 16, 1984, to April 30, 2001. The Great Salt Lake Datum Correction has a detailed explanation of these corrections.

 

Elevation area-volume curve for Great Salt Lake

Great Salt Lake is located on a shallow playa. Consequently, small changes in the water-surface elevation result in large changes in the surface area of the lake. This is particularly evident when the lake spills into the west desert at an elevation of about 4215 feet, greatly increasing its area.

At the historic average (1847-1986) surface elevation of 4,200 feet the lake covers an area of about 1,700 square miles. At the historic low elevation of 4,191.35 in 1963, the lake covered only 950 square miles. The drop of about 8.5 feet in elevation resulted in a loss of about 44 percent in surface area.

At historic highs during 1986 and again in 1987, the lake reached an elevation of 4,211.6 feet and had a surface area of about 3,300 square miles. The relation between water-surface elevation and corresponding surface area and volume of the lake is shown on an elevation-area-volume curve, also called a hypsographic curve (from the Greek, hypsos, meaning height). 

Hypsographic Curve

The hypsographic curve shown below can be used to determine area and total volume of Great Salt Lake (Gilbert and Gunnison Bays) by using the water-surface elevation from the Saltair Boat Harbor USGS gage located at the south end of Gilbert Bay. The data include diked areas for salt extraction located at the south end of Gilbert Bay.

(Includes ponds at Magnesium Corporation of America)

Graph showing Great Salt Lake hypsographic curve, that relates lake elevation to surface to volume

Graph showing Great Salt Lake hypsographic curve, that relates lake elevation to surface to volume(Public domain.)

References

  • Data were obtained primarily by digital planimetry of paper maps. The following data sources used to compile this curve: The 4,170- and 4,180-foot contour data for Gunnison Basin (north of causeway) were recorded from a map prepared by A.J. Eardley, University of Utah, April 1961.
  • The 4,170-, 4,180-, and 4,190-foot contour data for Gilbert Basin were recorded from Map 38, Navigational Chart of the Great Salt Lake South Arm, 1975, scale 1:80,000, compiled by W.M. Katzenberger, Utah Geological and Mineral Survey.
  • The 4,193-, 4,195-, and 4,200-foot contour data for Gilbert and Gunnison Bays were recorded from map Great Salt Lake and Vicinity, Utah, 1974, scale 1:125000, U.S. Geological Survey.
  • The 4,205-, 4,209-, and 4,212-foot contour data for Gilbert and Gunnison Bays were recorded from Satellite Image Map, Great Salt Lake and Vicinity, Utah, 1984, scale 1:125000, U.S. Geological Survey.
  • The 4,216-foot contour data was provided by the State of Utah, Division of Water Resources, as digital and paper copies.