Colorado-Big Thompson Project Reservoirs Fill with Seasonal Runoff

Above-average temperatures throughout Northern Colorado in June have accelerated snowmelt and runoff into Colorado-Big Thompson Project reservoirs.

Like other portions of Colorado, the headwaters of the Colorado River and tributaries of the South Platte River have seen short bursts of high temperatures that have caused high-altitude snow to melt and enter the nearby streams and rivers.

In the headwaters of the Colorado River, high streamflow levels have brought Lake Granby to capacity. On the Front Range, the Big Thompson River has seen high runoff levels, allowing C-BT Project managers to fill Horsetooth Reservoir around June 20. Due to lower-than-normal storage in Carter Lake at the beginning of the season, it is not expected to fill to capacity this year.

Water that gets stored in the C-BT Project reservoirs and is not used this year will go toward ensuring adequate water supplies for the 2025 water year.