Precipitation and the

Great Salt Lake

Patrick Loury and Eliana Manangòn

Precipitation and Lake Level of the Great Salt Lake (GSL)

Precipitation accounts for approximately 30% of the input to GSL (Lall and Mann, 1995)

This input has an important control on lake surface elevation (Stephens, 1990)

Since 1982, about 60% of elevation increase has resulted from greater than average precipitation and less than average evaporation rates

Snow is an important component of precipitation in the Great Basin, and accounts for about 85% of total precipitation input (Baskin, et al., 2002)

67%

30%3%

Inputs Into the Great Salt LakeStream Flow Precipitation Groundwater

Precipitation Breakdown By Watershed*

Four watersheds comprise the Great Basin:

West desertLargest area, least precipitation

Utah LakeOne of the largest freshwater lakes in the Western U.S.

Weber RiverSmallest area, most precipitation

Bear RiverContains the largest tributary contributing to GSL (Bear River)

*Data from http://www.greatsaltlakeinfo.org/Background

Watershed Area (mi2) Average Annual

Precipitation (in)

Minimum Recorded Precipitati

on (in)

Maximum Recorded Precipitati

on (in)

West Desert

18964 11 5 49

Utah Lake 3846 20 9 61

Weber River

2476 26 11 73

Bear River 7437 21 9 61

Total 32723 78    

Historical Data*

*Data from http://www.prism.oregonstate.edu

189518961897189818991900190119021903190419051906190719081909191019111912191319141915191619171918191919201921192219231924192519261927192819291930193119321933193419351936193719381939194019411942194319441945194619471948194919501951195219531954195519561957195819591960196119621963196419651966196719681969197019711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993199419951996199719981999200020012002200320042005200620072008200920100

5

10

15

20

25

30Annual Precipitation for Salt Lake

City

Time (years)

Prec

ipit

atio

n (in

ches

)

Average Value: 14.98 inStandard Deviation: 3.44 inMinimum Value: 9.06 inMaximumValue: 26.64 in

Precipitation Trend Over Time*

On a decadal scale, the average annual precipitation in SLC seems to be increasingIf this trend continues, the lake surface elevation will rise in responseHowever, the data is not certain:

Weak correlationRelatively short time period for data collectionLarge variability in data

05

101520

f(x) = 0.000931235 x³ − 0.0153974 x² + 0.4235058 x + 12.641576R² = 0.627789904636525

Average Annual Precipitation by Decade

Time (years)

Prec

ipita

tion

(in)

*Data from http://www.prism.oregonstate.edu

Note: For a full list of references, see handout