Participants break ground on Chimney Hollow Reservoir Project

A warm, hazy Friday morning found cause for a groundbreaking celebration just northwest of Carter Lake in Larimer County. 

A large tent surrounded by sandstone buttes, dry scrub and construction equipment was packed on August 6, as project leaders, government officials and members of the press gathered for the groundbreaking ceremony at Chimney Hollow Reservoir, part of the Windy Gap Firming Project. 

More than 20 years in the making, the brand new reservoir will create additional water storage for the twelve participating communities, including Longmont. 

“Today marks a long-awaited milestone that required years of hard work and cooperation among many groups with diverse interests to achieve a project that has benefits for everyone in Colorado,” said Northern Water General Manager Brad Wind.

Speakers at the groundbreaking included Wind, Municipal Subdistrict President Dennis Yanchunas, Windy Gap Participants Committee Chair Heather Banks, Northern Water Director of Engineering Jeff Drager, Northern Water Project Manager Joe Donnelly, Barnard Construction Vice President and Operations Manager Aaron Rietveld, Larimer County Commissioner Jody Shadduck-McNally, Eastern Colorado Area Manager for US Bureau of Reclamation Jeff Rieker and Colorado Water Conservation Board Director Becky Mitchell.

The speeches ranged from acknowledgement and appreciation of the collaboration from the governmental bodies, conservation agencies and participant communities, to the storied history and legacy of the project and the recreational benefits resulting from the reservoir.

The reservoir will provide storage for 90,000 acre-feet of water and a surface area of 740 acres at full capacity, stored behind a 350-foot-tall dam. Chimney Hollow will be the third tallest dam in the state of Colorado. The project entered into the federal permitting process in 2003, while the land itself was purchased from Hewlett-Packard in 2004 by Northern Water’s Municipal Subdistrict and Larimer County. 

Along with the reservoir, Larimer County will manage the Chimney Hollow Open Space Public Recreation Area, which will include 2,000 acres of forest. The day-use recreation area will host hiking, horseback riding, fishing and non-motorized boating.

In addition to the construction of the reservoir and recreational space, the Windy Gap Firming Project also includes environmental mitigation and enhancements to strengthen the Colorado River. The voluntary measures include water quality improvements and monitoring, endangered fish recovery programs, river connectivity and more. 

Construction of the dam and reservoir will begin officially on August 16, led by Barnard Construction Co. Inc. of Bozeman, Montana. The project is estimated to take four years until the dam and reservoir are complete, according to Rietveld. 

“For our part, I think we’ve established an outstanding management team,” Rietveld said. “We understand that there are a lot of eyes on this project at the local, state and federal level, and I think we’re up to the challenge.”

The dam itself will be constructed with an asphalt core, while the rock-fill shoulders will be made of materials mined from the reservoir footprint, in order to reduce costs and pollution while increasing storage capacity. The on-site quarry is permitted at 63,000 tons per day, making it the largest mining operation in Colorado according to Donnelly. 

Representatives from Longmont at the groundbreaking ceremony included Councilmembers Marcia Martin, Joan Peck and Susan Hidalgo-Fahring, along with State Representative Karen McCormick. 

“It was really great to hear the history of the many years that went into it and the tremendous foresight and persistence in coming up with a plan that will supply water and recreation for Coloradans well into the future,” McCormick said. “It’s really important and historic to be here today and see all these people that have worked so hard on this project.”

Martin, Longmont’s representative for the Participants Committee for Windy Gap and Chimney Hollow said, “There were times we thought we’d never get here, so it’s really great to be at the groundbreaking and start of construction for the Chimney Hollow project.”