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 desert

Largest area, least precipitation

Utah Lake

One of the largest freshwater lakes in the Western U.S.

Weber River

Smallest area, most precipitation

Bear River

Contains 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)

Pre

cip

itati

on

(i

nch

es)

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 increasing

If this trend continues, the lake surface elevation will rise in response

However, the data is not certain:

Weak correlation

Relatively short time period for data collection

Large variability in data

0

5

10

15

20

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

Average Annual Precipitation by Decade

Time (years)

Pre

cipit

ati

on (

in)

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

Note: For a full list of references, see handout