WSP01414

• File Number: 8449.918
• Description: South Platte Projects
• State: CO
• Basin: South Platte
• Date: 8/1/1982
• Author: CWCB
• Title: South Platte River Basin Assessment Report
• Water Supply Pro - Doc Type: Publication

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Both types at tributaries, as well as the South Platte River itself,

exhibit substantial variations in streamflow from season to season and from

year to year. Characteristically, as much as 75 percent of the runoff of

mountain streams may occur during the months of May through July. In

tributary sub-basins of the Plains zone, summer thunderstorms may result in

relatively large streamflows during July, August, or September. On a

relative basis, substantially larger annual streamflow volumes per unit

area are generated in the mountains than in the plains. These pronounced

seasonal and Ioeational variations suggest the need for water storage

projects for water uses requiring sustained yields or year-round supplies.

The reach of the South Platte River extending from about Henderson

downstream is underlain by valley-fill alluvium and dune sand containing an

unconfined aquifer. This aquifer varies in width from about 1 mile to over

10 miles; generally, it is narrowest downstream from Sterling and widest

immediately above Fort Morgan where Kiowa and Bijou Creeks discharge into

the SOuth Platte River (Figure 8). The aquifer is estimated to contain as

much as 8 million acre-feet of water in storage and is connected to the

surface flow of the river (Hurr and others, 1975). Upstream from

Henderson, the valley-fill aquifer is limited in size and storage

capabilities.

Transbasin diversion projects have delivered a significant amount of water

into the South Platte River basin from Colorado's western slope and the

Laramie River basin. This water, averaging nearly 377,000 acre-feet

annually over the 1953-79 water year period, has been used for

agricultural, municipal and industrial purposes. Notable examples of

tranebasin-import projects are the Moffat collection system and the Blue

River system operated by the Denver Water Board, and the Colorado-Big

Thompson Project, operated by the u.s. Bureau of Reclamation and the

Northern Colorado Water Conservancy District. The significant transbasin

import projects are discussed later.

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