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
t
System Supplying Water Storage Supply"I' (acre-feet) (acre-feet per year)
North Sterling Outlet Canal 5,000 1,750
10,000 3,000
IHarmony Ditch 5,000 4,100
10,000 6,000
IPeterson Ditch 5,800 4,600
(1)At 90%reliability,based on 1943-97 period of record and assuming that water can be diverted in winter months.
IThe storage analysis is based on using existing water conveyance canals and ditches to fill
the storage. Only ditch capacity in excess of historic use in the 1943-97 period was assumed
Ito be available to deliver water from the river into storage.
Twenty-two storage sites were identified (see Table ES-1) and evaluated through a
I systematic screening process. Storage sites are depicted on Figure ES.2. Five conventional
dam/reservoir projects, the enlargement of Julesburg Reservoir, and the Ovid ring-dike
project were found to be the best storage options,based on cost, permitting, institutional and
Iother factors considered in the screening process. The five conventional dam/reservoir
projects are located on drainages tributary to the South Platte River on the north side of the
Iriver from about 2 to 20 miles upstream of Julesburg Reservoir.
In addition to these storage options, the idea of a"mined"reservoir was introduced later in
Ithe study process. Gravel pits in the Denver metro area are being converted and/or
developed during mining into lined-water storage facilities. As demands for concrete
I aggregates and road base materials increase, due to the I-25 widening and light-rail project
(T-REX Project) and other large-scale construction projects, it would be prudent to consider
such potential water storage development opportunities. Key issues include: the near-term
I demand for sand and gravel in the metro area, relative to more locally available sources; the
suitability of materials in the Lower Basin alluvium for aggregates and base course; the
timeframe required to create storage opportunities; and the costs associated with transporting
I materials from the project area(downstream of Sterling, Colorado)to the metro area. Further
study of this storage alternative is planned for the feasibility phase of the project.
INon-structural measures will need to be explored as part of detailed planning for the project;
however, potentials appear to be limited. Reservoir re-operation, water exchanges, and water
Ibanking may have merit within the context of a larger structural solution.
Six alternative plans were developed by the study team using the plan components selected
Iduring the screening evaluation. These alternatives are summarized below:
I
GEI Consultants, Inc. ES-2 01002 Dec 2001 Lower South Platte River Study