Lake Granby

Northern Colorado, USA 

Situated on a turbine shaft centerline of 8,060 feet (2,457 meters) above sea level in Northwest Colorado on the West Slope of the US Continental Divide, Lake Granby is an integral part of Northern Colorado Water Conservancy District’s (NCWCD) Colorado-Big Thompson Project.  The new Lake Granby hydro plant is positioned to provide the District with revenue recovery for decades to come.

The fully automated and mostly unmanned plant consists of two, Gilkes 450mm G150 Francis turbines coupled to 900rpm synchronous generators; with each turbine having an electrical output of approximately 580kW, at the rated head and flow. The turbine runners utilized on this project are the enhanced high-efficiency runners that Gilkes Research and Development department, utilizing the latest CFD software, developed to increase the efficiency and power output of the runners. 

An important feature of the project was to have two, same-size Francis turbines to recover as much energy as possible under varying flow conditions; accommodating the changing flow releases NCWCD is required to deliver to the Colorado River. The plant is able to operate using a single turbine when the flow demand is lower, and to then have the ability to bring on a second machine automatically as the flow demand increases. The PLC software then balances the operation of both machines by sharing the flow equally, to ensure that the maximum energy output and efficiency is attained.

Thanks to the efforts of all involved the project was commissioned approximately 2 months ahead of schedule, allowing for the maximum energy recovery during the high flow-release months for 2016.



  • 2 x Gilkes 450mm G150 Francis Turbines
  • Generator - 645kVA, 60hz, 3-Phase, 900rpm with roller bearings
  • Generator controls & switchgear - PLC based fully automated controls, turbine governor, electrical protection system, station services, DC battery back-up system, MCC & generator switchgear
  • Hydraulic control modules
  • Installation & commissioning

Key Stats

  • Commissioned May 2016
  • Power 580 kW (each)
  • Net Head 64
  • Flow 38 cfs
  • Turbines 2 x Gilkes 450mm G150 Francis Turbines

A few months into full operation following the full commissioning of the project, NCWCD’s Project Manager, Carl Brouwer commented – “Granby continues to run successfully. No issues at all”