Colorado-Big Thompson Project Overview

Presented byRon ThomassonWater Resources EngineerEastern Colorado Area Office

Reclamation and the C-BT

• Authorized by Congress in 1937• Reclamation built, owns, and primary operator• Primary purpose: supplemental water (Ag and M&I)• Secondary purpose: hydro-electric power generation• Construction 1938-1952• Six powerplants• 10 reservoirs

Colorado-Big Thompson Project

Colorado-Big Thompson ProjectTypical Operations

• West Slope – store all inflow in excess of minimum streamflow requirements

• East Slope – divert water through the Adams Tunnel at a time and volume in order to:– Meet demands

– Maximize hydropower generation

– Accommodate recreation

– Accommodate maintenance activities

Granby Dam

Green Mountain ReservoirTypical Spring Operation

• Fill reservoir by mid July

• Avoid spilling the reservoir to maximize power generation

• Participate in Coordinated Reservoir Operations (Peak Enhancement - minimum 15-Mile Reach flow of 12,900 cfs)

Green Mountain Dam and Reservoir in early spring

Green Mountain Reservoir Typical Summer/Fall Operations• Bypass inflow to meet

downstream senior water rights (Shoshone/Grand Valley)

• Replacement releases for out-of-priority depletions at Granby and Willow Creek

• Releases to the West Slope Beneficiaries and for endangered fish

Green Mountain Reservoir in late summer 2003

Opportunities• Assist in demand projections

– Northern Water– Denver Water– Grand Valley

• Assist USFWS in setting target flows– Peak enhancement– Late summer flows in 15-Mile Reach

• Initiate drought mitigation discussions (e.g. Shoshone call reduction)

Questions?

Green Mountain Dam and Powerplant on the Lower Blue