Lower Colorado Basin

CRFSMarch 30, 2010

Virgin River

NWS-SWS: 90

NWS-ESP: 60 55 (+8-15% El Nino weighted)

NRCS daily: 80

NRCS statistical: 78

Coordinated: 80 / 195% median or 125% average

March 1 March 25

Virgin Basin Snow Plot2005 / 2010 / Average

Virgin River Flow (incl. Santa Clara)2005

A comparison with 2005

2005 Flood

2005 snowmelt

Virgin Basin6100 ft

Salt Basin6800 ft

National Operational Hydrologic Remote Sensing Center - NOAA

2010 LOWER COLORADO BASINLAKE MEAD LOCAL (Intervening Flow)

           March 120 KAF (100% of average)            April  120 KAF (104% of average)            May  80 KAF ( 96% of average)

April - July Forecast: 270 KAF ( 93% of average) March - July Forecast: 390 KAF ( 95% of average)

ESP Generated

Colorado River -

Lake Powell to Diamond Fork

Little Colorado

Paria River

Virgin River

Muddy Creek

Intervening Flow Forecasts: Lake Powell to Lake Mead / Where is the skill ?

Muddy3% Virgin

22%

Paria2%

Little Colorado18%

Havasu5%

Kanab1%

Powell to GC18%

GC to Diamond31%

Annual Inflow Powell to Mead Tributary

Distribution(CBRFC calculated using USGS gages)

Inflow Between Powell & Mead:

Lake Mead Inflow

Forecast Periods: Virgin Basin (Snow + Rain) & Arizona Basins (Rain, some snow)

April – July Runoff

Progressive Forecast Period

Jan-MayJan 15 – MayFeb – May Etc.

Virgin River Basin

Arizona & New Mexico Basins

Winter 2010 Highlights

Winter storm pattern that resulted was in line with the El Nino climate conditions

Significant rainfall in the Lower Colorado during the 3rd week of January (~10” in 24 hrs)

Very large snowpack in Arizona, significant snow at lower elevations Much above median volumes observed in January, much above median seasonal

volumes expected.

Forecast Challenge: Possibility of additional large precipitation events (El Nino) Forecast Challenge: The non-typical large snowpack and resulting volumes. Forecast Challenge: Dry soils exist under high elevation snowpack.

2010 LOWER COLORADO BASINSALT / VERDE

January 20-23, 2010 Precipitation

January flows in the Lower Colorado Basin

Jan Volume 850 % of median

Feb Volume 710 % of median

Salt River - Roosevelt

Weighting ESP for El Nino years resulted in:

Feb 1st Forecast (Feb-May) of +27% over raw ESPMar 1 Forecast (Mar-May) of + 5% over raw ESP