22-04-2025
Here's when Northern Water will start filling Chimney Hollow and its planned opening date
Water will start flowing into Chimney Hollow Reservoir 5 miles southwest of Loveland starting in early July, shortly after completion of what will become the fourth-largest dam in Colorado.
Jeff Stahla, Northern Water spokesperson, said the reservoir will slowly be filled to 45,000 acre-feet, half of its 90,000 acre-feet total capacity, by the end of 2025 or early 2026. For comparison, Horsetooth Reservoir can hold a maximum of 156,735 acre-feet of water and Carter Lake 112,230.
Crews are expected to complete the 350-foot-tall dam that stretches 3,700 feet long by mid- to late June, Stahla said.
"We are filling it slowly so we can test for dam safety," Stahla said.
Stahla said the reservoir is expected to be operational in 2027, which is when Larimer County plans to open its 1,847-acre Chimney Hollow Open Space next to the reservoir.
The county unveiled its recreation management plan for the future open space, which includes hiking trails, parking lots and restrooms, boating and swimming in the reservoir and access to nearby Carter Lake.
Chimney Hollow Reservoir is part of Northern Water's Colorado-Big Thompson system that moves water from west of the Continental Divide to east of the divide into Horsetooth and Carter reservoirs and soon Chimney Hollow. The water is used for agricultural irrigation, municipal drinking water and recreation.
On-site construction of Chimney Hollow began in August 2021.
Cost of the Chimney Hollow Reservoir project will be $584 million for construction and another $166 million for environmental mitigation, engineering and cost of the property, according to previous Coloradoan reporting. The $750 million tab will be picked up by the 12 entities that will receive 30,000 acre feet of water when it's up and running.
Larimer County and Northern Water jointly purchased the 3,500-acre property on which the reservoir and open space are located in 2004 from the former Hewlett-Packard company. Cost was $3.8 million with nearly $1 million of that coming from Great Outdoors Colorado Lottery money.
This article originally appeared on Fort Collins Coloradoan: When Chimney Hollow Reservoir will start filling, open to recreation
