RCC/EAC Water Supply Update

• File Number: 8461.450
• Description: EAC/RCC
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 11/16/2005
• Author: Bureau of Reclamation ‎(Wyoming Area Office)‎
• Title: RCC/EAC Water Supply Update
• Water Supply Pro - Doc Type: Meeting

Wyoming Area Office Page 1 of 2
Bureau of Reclamarion
North Platte River Water Supply Update
November 16, 2005
Figure 1 shows current reservoir storage conditions for Reclamation reservoirs as of November
13, 2005, on the North Platte River and provides a comparison of total inflow, total Guemsey
Reservoir outflow, and total September 30 system storage for water years 2002 through 2005,
including the statisrical "most probable" 2006 operarions complied from the November operating
plan. The term "kaf' used in this report represents acre-feet times 1000. The North Platte total
system storage of 1,006.5 kaf at the end of water yeaz 2005 represents an increase in the system
storage of 218.8 kaf over water year 2004 (787.7 ka fl. This small system storage recovery is
attributable to conservarion efforts af the irrigation districts as releases from Guemsey Reservoir
for downstream irrigarion demand were discontinued on September 9, 2005. The 1Vorth Platte
Project Irrigation Districts conserved approximately 400 kaf of carryover storage.
The total system probable inflow for 2006 is estimated to be 99% of average (1328.5 kaf/1336.0
ka fl. The total Guemsey Reservoir probable outflow for 2006 is estimated to be average and
reflects an assumed full irrigation delivery for the North Platte Project contractors. The
projected total system probable storage on September 30, 2006, is estimated to be 67% of
average (9$7.2 kaf/1463.3 kaf) or 35% 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. This early SNOTEL information shows
the SWE is near average for the upper basin and below average for the lower basin. As of
November 15, 2005, the Natural Resources Conservation Service (NRCS) reported the SWE to
be 99% and 81% of average (figure 4) for the upper and lower basin, respectively. The North
Platte River basin did benefit from recent snowfall on November 14.
Table 1 shows the actual inflows, Guemsey outflow, and end-of-month total system storage for
the month of October and the projected November thraugh September operations based on
reasonable minimum, most probable, and reasonable maximum inflow conditions. These
statistical inflow conditions provide the range for Reclamarion operating plans in the North
Platte River Basin. The operating plans are updated monthly to reflect changing inflow
conditions. T'his report focuses on the information associated with the November most probable
operating plan.
The actual total system inflows for the month of October were 68% of average (34.1 kaf/50.4
kaf). Table 1 also includes the accompanying information for water year 2005 and the 30-year
average (1976-2005) for comparison. Graph 1 through Graph 3 displays this information in
graphical format. Based on the November most probable North Platte River Operating Plan, the
North Platte Pathfinder ownership (refer to NPRAOP page 3) is estimated to fill (1,016.5 kafl in
June, leaving about 27.2 kaf of accrual for the Kendrick Project.
Assuming the Pathfmder Modification Project was in operation, the North Platte Pathfinder