Project History

The original Southern Water Supply Project pipeline carries Colorado-Big Thompson Project and Windy Gap Project water 110 miles from Carter Lake to several Northeastern Colorado communities. The project was initiated when the City of Broomfield needed a new water supply source due to potential contamination in the city's Great Western Reservoir. Other communities had increasing demands and water quality standards, requiring a dedicated water delivery pipeline. The original Southern Water Supply Pipeline met Broomfield's needs and also provided other communities with a year-round water supply. In addition, sharing a single pipeline was less costly than if each participant had built its own project.

Construction of the pipeline began in 1993 and was completed in 1999. Due to project participants' increasing water demands, particularly during the higher-demand summer months, the West Longmont Pump Station was added in 2003 to increase the capacity of the pipeline. Two years later an additional pump station at Broomfield followed to further increase the capability to deliver water during the high-demand months.

SWSP has 12 project participants:

  • Fort Morgan
  • Broomfield
  • Hudson
  • Berthoud
  • Longmont
  • Erie
  • Louisville
  • Morgan County Quality Water District
  • Little Thompson Water District
  • Central Weld County Water District
  • Superior

Green Power - Trout Hydropower Plant

When water is released from the Carter Lake through the reservoir's new outlet, it enters the Robert V. Trout Hydropower Plant where hydroelectric power is generated. The plant was Northern Water’s first hydroelectric project and includes two 1,300-kilowatt turbines. Hydroelectric power is a clean energy source produced by harnessing energy that is already created by the water’s movement within the existing Carter Lake facilities.

Carter Lake - SWSP II Water Supply

Carter Lake is the second largest reservoir in the C-BT Project's East Slope distribution system. The reservoir stores 112,230 acre-feet of water and was completed in 1952. The earthen Carter Lake Dam has a height of over 200 feet and is over 1,000 feet long.

The reservoir will provide raw water to the four SWSP II participants – City of Boulder, Town of Berthoud, Left Hand Water District and Longs Peak Water District.

In 2008, a new outlet was completed at Carter Lake that added greater flexibility to release water year-round to municipal and industrial water users in the central and southern portions of Northern Water’s service area.

The outlet structure consists of:

  • A 100-foot-tall multi-level intake tower
  • An 800-foot-long tunnel
  • A 400-foot-long penstock connecting the outlet to the St. Vrain Supply Canal