Lower South Platte River Study

• Contractor Name: Colorado Water Conservation Board
• Loan Projects - Doc Type: Feasibility Study

ILower South Platte River Study
Colorado Water Conservation Board
December 2001
The Lower South Platte Water Conservancy District (LSPWCD) also manages water in the
iLower Valley.
The Northern Colorado Water Conservancy District (NCWCD) provides supplemental water
I to East Slope water users via operation for the Colorado-Big Thompson (CBT) Project,
which diverts water from the Upper Colorado Basin into tributaries of the South Platte River.
IAvailable water supplies include native South Platte River flows, return flows from
transmountain water diverted by the Colorado-Big Thompson Project, return flows from
I transmountain water developed by municipal water users in the Denver metropolitan area
(Denver, Aurora, and others) and participants in the Windy Gap Project (Municipal/
Subdistrict of the NCWCD).
IHistoric diversions by the larger ditch systems in the study area are summarized below:
I Diversions in Acre-Feet
Average
System Maximum Minimum for Period
INorth Sterling Inlet 1943-95 157,700 53,800 102,000
North Sterling Outlet 1943-99 97,800 43,000 75,000
I Harmony 1950-98 78,700 12,900 31,800
Peterson 1950-98 17,200 940 7,960
IBoth the North Sterling and Julesburg systems rely extensively on reservoir storage to
manage their water supplies. Typically, water is diverted from the river into storage of North
I Sterling Reservoir during the October-April period. Water is released from storage during
the May-September period when only limited water may be available under direct flow
rights. Harmony Ditch diverts water in the April-October period and when water is available
Iduring November-December. Storage volumes are 81,400 acre-feet in North Sterling
Reservoir and 28,200 acre-feet in Julesburg Reservoir.
I2.2 Current Groundwater Supplies and Uses
I Groundwater is an important water supply for irrigators and municipalities in the Lower
South Platte Basin.
IGroundwater wells draw water from formations that are hydraulically connected to the river.
The Colorado State Engineer's Office (SEO), acting through statute and regulation, requires
that groundwater wells in the South Platte River Basin replace their depletions consistent
Iwith the South Platte Rules and Regulations to prevent injury to senior water rights and in
District 64 to also assure compliance with the terms and conditions of the South Platte
ICompact. The Ground Water Appropriators of the South Platte (GASP) is an augmentation
GEI Consultants, Inc. 2-2 01002 Dec 2001 Lower South Platte River Study
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