South Platte River Basin

The South Platte Basin (including the Republican River Basin) covers approximately 27,660 square miles (26.4 percent of the state’s area) in the northeast portion of Colorado. Major tributaries include Cache la Poudre River, Big Thompson River, and the North and South Forks of the Republican River. 

Quick Facts
Description Value (approximate)
Irrigated Acres (2010) 1                  857,770

                 Irrigated Lands Graph
Decreed Points of Diversion 1 8,361
Decreed Wells 1 54,065
Major Reservoirs 2
  • Horsetooth Reservoir
  • Carter Lake
  • Eleven Mile Canyon Reservoir
Normal Storage (acre-feet)
  • 152,000
  • 112,200
  • 97,800
Major Imports into Basin 2
  • Adams Tunnel
  • Moffat Tunnel
  • Roberts Tunnel
Average Diversions (acre-feet) (1971-2003)
  • 218,142
  • 52,155
  • 53,676
Major Exports from Basin 2


1 Source: CDSS, total values derived from GIS Data for South Platte Basin
2 Source: Statewide Water Supply Initiative Fact Sheet for South Platte Basin, CWCB, 2006

Compact Facts
  • South Platte River Compact of 1923:  The South Platte River Compact establishes Colorado’s and Nebraska’s rights to use water in Lodgepole Creek and the South Platte River based on the flow of the South Platte River at Julesburg, Colorado.
  • Republican River Compact of 1942:  The Republican River Compact establishes the rights of Colorado, Nebraska, and Kansas to water in the Republican River Basin and makes specific allocations for consumptive use from identified streams.

         South Platte River Basin

Basin Updates
  • Alluvial Groundwater Model  Update Report Available (June 2017) 
  • SPDSS alluvial groundwater model files are available upon request; they are too large to download through the website. Please contact Mary Halstead, or Erik Skeie for more information.

 Additional Information