Drought in Managed Systems—Snake River PlainPresented by David Hoekema

Water Supply Committee Meeting

Date: April 14th, 2015

Idaho Water Supply CommitteeIdaho Department of Water Resources (IDWR) hosts meetings

• Meets every 2nd week of the month (Jan-April)

• April 1st marks the beginning of the Irrigation Season and Peak

Snowpack.

• Membership

- IDWR, Homeland Security, Idaho Department of

Agriculture, Idaho F&G, USBR, NWS, NRCS, USACE,

USGS, USFS, Farm Service Agency, IPCo

• Responsibilities

- Track drought, coordinate with agencies, provide public

information

Defining Drought in the West• Climate (Rain, Temp, and SWE)

• Warm and Dry Winter

• Unusual August rains (PDSI, SPI, etc.)

• Storage Supplies vs. Irrigated Regions

• USBR Hydromet

• Supply vs. Demand

• Groundwater (responds to climate and management)

• Managed conjunctively

• Managed thru mitigation (rental pools)

2011

2013

2011

2013

Eastern Snake River BasinWestern Snake River Basin

Payette River

Boise River

Eastern Snake River Basin

Western Snake River Basin

0

5

10

15

20

25

30

1-Oct 1-Nov 1-Dec 1-Jan 1-Feb1-Mar 1-Apr 1-May 1-Jun

Sn

ow

Wa

ter

Eq

uiv

ale

nt

[SW

E, in

]

North Fork Composite[Long Valley, Bear Basin, Squaw Flat,

Burndage Reservoir, Secesh Summit, Big Creek]

Median 1981-2010 2013 2014 2015

0

5

10

15

20

25

30

Sn

ow

Wa

ter

Eq

uiv

ale

nt

[SW

E,

in]

Long Valley-SnotelElevation 4890 ft

Median 1981-2010 2013 2014 2015

60%

42%

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

12,000,000

14,000,000

16,000,000

18,000,000

20,000,000

Cu

mu

lati

ve S

tora

ge C

han

ge (

acre

-fe

et)

Cumulative Volume Change of Water Stored Within ESPA

Water Budget Volume Change ESPAM1.1 Simultaneous Volume Change

Declines in the eastern Snake Plain aquifer