SPDSS_Task83_PrepareInitialWaterBudgets

• Title: SPDSS Task 83 - Prepare Initial Water Budgets
• Description: This memorandum summarizes the results of Task 83 of the Consumptive Use and Water Budget portion of the South Platte Decision Support System ‎(SPDSS)‎ effort.
• Decision Support - Doc Type: Task Memorandum
• Date: 4/7/2005
• DSS Category: Water Budget
• DSS: South Platte
• Basin: South Platte
• Contract/PO #: C153953
• Grant Type: Non-Reimbursable
• Bill Number: SB01-157, HB02-1152, SB03-110, HB04-1221, SB05-084, HB06-1313, SB07-122
• Prepared By: Leonard Rice Engineering

Table 1
South Platte River Basin, North Platte River Basin and Laramie River Basins
Initial Average Annual Water Budget Runs
(Values in 1000s of Acre-Feet)
Water Budget
Component South Platte North Platte Laramie River
Water Budget Task 82 Water Budget Task 82 Water Budget Task 82
Inflows
Precipitation ~ 18,080 ~ 17,104 ~ 2,187 ~ ~ 538
Surface Water Inflows ~ 0 ~ ~ 0 ~ ~ 0
Imports 387 400-426 O I 0
Ground Water Inflows 75 75 O I 0
Total 18,542 2,187 538
Outflows
Agricultural CU 1,760 1.15 ft/ac - 102 155 3.4
1.75 ft/ac. 1.97 ft/ac 1.10 ft/ac. 1.81 ft/ac. 1.10 ft/ac.
M&I CU ~ 330 ~ 186 ~ 0.2 ~ 0.29 ~ 0.01
Livestock CU ~ 17 ~ 18.7-19.8 ~ 0.53 ~ 0.67 ~ 0.036
Reservoir Evaporation ~ 238 ~ 233 ~ 12.3 ~ ~ 1.5
Native Veg. CU* ~ 15,737 ~ 2.67 ft/ac ~ 1,765.1 ~ ~ 389
Surface Wtr Outflows ~ 445 ~ 300-393 ~ 305 ~ 317 ~ 125 ~ 120
Exports O 1.9 1.3 I 19 I 19.7
Ground Wtr Outflows ~ 15 ~ 8-20 ~ 0 ~ ~ 0
Total 18,542 2,187 538
Change in Storage
Surface Water ~ 0 ~ 0 ~ 0 ~ ~ 0
Ground Water ~ 0 ~ -0.7 to -19 ~ 0 ~ ~ 0
Total 0 0 0
Notes:
* Native vegetation CU is calculated by StateWB based on other water budget inputs. Native vegetation CU includes
consumptive use by native vegetation (phreatophytic species, non-irrigated lands, including grasslands, etc.), sublimation
of winter precipitation, plus error associated with other estimates.
Results and Comparison
Inflows
• Precipitation
The precipitation contribution for the entire South Platte River drainage in the states of
Colorado, Wyoming, and Nebraska from the USBR study (17,104,100 acre-feet per year -
17,104 kaf/yr) is less than the value calculated for the South Platte River water budget in the
state of Colorado (18,080 kaf/yr). The difference in values maybe due to different source data
(the USBR study was published in 1977) and different handling of the raw precipitation data
input.
• Surface Water Inflows
No surface water inflows occur at the top of each of the river basins.
• Imports
Transmountain imports to the South Platte River water budget (387 kaf/yr) are similar to those
from the studies reviewed (400 kaf/yr to 426 kaf/yr) with the differences likely due to variable
study periods.
Task83 final.doc 7 of 15 Apri17, 2005