#Colorado-Big Thompson operations update

Olympus Dam photo via the US Bureau of Reclamation.

From email from Reclamation (Elizabeth Jones):

Olympus Dam near Estes Park, Colorado impounds Lake Estes. The lake is the afterbay for Estes Powerplant, a hydroelectric powerplant that can produce up to 45 MW each hour. Colorado-Big Thompson Project water from the west slope fuels the Estes Powerplant. Project water discharged from Estes Powerplant is diverted from Lake Estes, routed to additional hydroelectric powerplants on the Front Range and is then stored in Carter Lake or Horsetooth Reservoir. Project water is rarely released from Olympus Dam into the Big Thompson River.

This is the season for snow-melt runoff into Lake Estes. In the past 10 days, natural inflow into Lake Estes has increased from a low of about 250 cubic feet per second (cfs) to a peak flow of about 1,020 cfs. Currently, natural inflow is decreasing (around 700 cfs); however, warmer or wetter days could result in natural inflow increasing again and the recent peak inflow could be surpassed.

Olympus Dam is not an authorized flood control structure. As such, the natural snow-melt or precipitation runoff that flows into Lake Estes is released from Olymus Dam into the Big Thompson River. Under normal operations, Olympus Dam does provide the benefit of shaving off the peak inflow. One way it does so can be explained using recent operations. During two days this week when peak inflow into Lake Estes was about 1,000 cfs, maximum release from the dam was 880 cfs. This is because outflows are generally the day’s average. Outflow does not follow the within-day variation, which ranged from 714 cfs to 1,020 cfs within a 24-hour period. Releases from Olympus Dam in the near term will be driven by whatever Nature provides from the headwaters of the Big Thompson watershed.

As the snow-melt runoff season progresses, Reclamation will provide information to the public regarding expected flows released from Olympus Dam.

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