PRRIP Meetings North Platte 04/21/2009

• Description: Agenda, Update of Districts 2009 Operations, North Platte River Water Supply Update, RCC REpresentatives and Alternates for the Upcoming 2010 Water Year Divisions 1, 6
• State: CO
• State: NE
• State: WY
• Basin: North Platte
• Basin: South Platte
• Water Division: 1
• Date: 4/21/2009
• Author: Various
• Title: Operations, North Platte River Water Supply Update, RCC Representatives and Alternates for the Upcoming 2010 Water Year Divisions 1, 6
• Water Supply Pro - Doc Type: Meeting

Wyoming Area Office
Bureau of Reclamation
North Platte River Water Supply Update
April 21, 200 i
Page 1 of 2
Figure 1 shows current reservoir storage conditions for Reclamation reservoirs as of April 18,
2009, on the North Platte River and provides a comparison of total inflow, total Guernsey
Reservoir outflow, and total September 30 system storage for water years 2006 through 2008,
including the "expected" 2009 operations compiled from the April operating plan. The term
"kaf' used in this report represents acre -feet times 1000. The North Platte total system storage
of 1195.8 kaf at the end of water year 2008 represents an increase in the system storage of 489.5
kaf over water year 2007 (706.3 kaf). This system storage increase is attributable to above
average snowmelt runoff in the upper basin and a major rainstorm event in late May that dumped
6 -8 inches over a couple of days in the lower North Platte Basin. Irrigation releases from
Guernsey Reservoir for downstream irrigation demand were discontinued on September 11,
2008. The North Platte Project Irrigation Districts conserved approximately 572.7 kaf of
carryover storage.
The total system expected inflow for 2009 is estimated at 1,216.6 kaf or 92% of average. The
total Guernsey Reservoir expected outflow for 2009 is estimated to be 1054.4 kaf. The projected
total system expected storage on September 30, 2009, is estimated to be 83% of average (1172.0
kaf /1408.7 kaf) or 42% of the total conservation capacity of the system.
Figure 2 and Figure 3 provide snow water equivalent (SWE) information expressed in inches of
water for the upper and lower North Platte River basins. The SNOTEL information shows the
SWE is above average for the upper North Platte River Basin and at average for the lower North
Platte River Basin. As of April 19, 2009, the Natural Resources Conservation Service (MRCS)
reported the SWE to be 112% and 101% of average (Figure 4) for the upper and lower basin,
respectively, thanks to recent snow storms. Reclamation's April 1 forecast of the April through
July runoff in the basin above Seminoe Reservoir is 700 kaf (99% of average) and 100 kaf (82%
of average) for the basin between Alcova and Glendo Reservoirs. The NRCS SWE data on
March 31, 2008 were 104% and 88% of average for the upper and lower North Platte River
basins, respectively, when these forecasts were made. A comparison of the SWE curves for
2006 and 2008 in Figure 2 and Figure 3 demonstrate the dependency of the North Platte River
Basin on continued Spring snows. For example, a well above average snowpack on April 1,
2006 only produced a runoff of 546.1 kaf, whereas a near average snowpack on April 1, 2008
provided a runoff of 955.9 kaf due to continued Spring snows. Reclamation's determination of
the forecasted supply as of April 1 is above 1,100 kaf (Figure 5), which indicates at this time
there is no need to allocate storage.
Table 1 shows the actual total system inflows, Guernsey outflow, and end -of -month total system
storage for the month of October through March and the projected April through September
operations based on minimum, expected, and maximum inflow conditions. These inflow
conditions (Table 2) provide the range for Reclamation operating plans in the North Platte River