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Chatfield Reservoir expansion project will start this fall

Swim beach, boat ramp, other recreational features will be rebuilt as part of project

The Dean family from left to ...
Andy Cross, The Denver Post
The Dean family from left to right, Jaxon Dean, (son) Seth Dean, (dad) Samantha, (mom) and their daughter Jaden head out on a stand-up paddle board trip at Chatfield Reservoir May 25, 2017 in Jefferson County.
Joe Rubino - Staff portraits in The Denver Post studio on October 6, 2022. (Photo by Eric Lutzens/The Denver Post)
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Take a good look at Chatfield State Park, because it’ll look different a year from now. And by this time in 2019, the popular recreation area at the confluence of Arapahoe, Douglas and Jefferson counties will have updated facilities and the eponymous reservoir within it will be larger.

After more than a decade of discussion and planning, the Chatfield Storage Reallocation Project is set to begin later this year. The more than two-year construction effort will prepare the reservoir to accommodate an additional 20,600 acre feet of water to meet a variety of municipal, agricultural and industrial needs. Currently, the reservoir holds about 27,000 acre feet of water. Eventually it will hold up to another 20,600 acre feet of water and the water level could rise as much as 12 vertical feet, officials said.

Beginning in winter and continuing through spring, the swim beach and north boat ramp will be reconstructed to accommodate the future shoreline. By the end of 2019, many other features of the park, including the marina, day use areas and South Platte bridge will be visited by construction crews and earth movers.

The park will remain open throughout construction. Higher water levels will change features along the reservoir’s shore.

“It’s going to change. But when we’re all said and done, what we’re looking at is all the same outdoor recreation opportunities that we offer today,” park manager Scott Roush said. “If we have a trail today, after reallocation, we’re going to have that trail. It may move but we’re going to have the same things. Everything is being replaced in-kind.”

The project will cost an estimated $160 million, said Tim Feehan, general manager of the Chatfield Reservoir Mitigation Co., whose eight partners — including Castle Rock, Centennial Water and Sanitation District and the Castle Pines Metropolitan District — will pay that tab in proportion to the amount of water storage each will be granted. Of that, $140 million has already been set aside in escrow.

Groundbreaking awaits final design approval from the Army Corps of Engineers, which built, owns and leases the reservoir to Colorado Parks and Wildlife for recreational use, Roush said. Preliminary designs and a tentative construction schedule are available online at Chatfieldreallocation.org, a project website created by Chatfield Reservoir Mitigation Co.

The swim beach is scheduled to close for reconstruction in late fall and reopen for use by Memorial Day weekend 2018. The beach and park perimeter road will be moved to the west, away from the present shoreline, to accommodate greater water fluctuations, effectively creating another 200 feet of beach area at low water. The parking lot will be expanded and the shower, restrooms and other features will be rebuilt. The north boat ramp also is scheduled to reopen to use by next Memorial Day weekend.

“A lot of the work is going to be done over the wintertime when the visitation is down and when the swim beach is closed and when the boat ramps are closed,” Roush said. “It’s about minimizing the time when the users would not be able to use those areas.”

Changes to the shoreline necessitate relocation of many trees, Roush said, and he’s confident the trees will re-establish themselves as they did after the Army Corps first constructed the reservoir as a flood control mechanism in the 1960s and 1970s. 

Denver resident Roxann Lopez visited Chatfield with her family last week to swim. She hadn’t heard about the reallocation project but supports changes that will better accommodate the state’s growing population.

“I think it’s great if you’re making the changes to meet the needs of people,” she said.

The project will expand recreational opportunities. For example, the reservoir currently features about 1,400 surface acres of water when full. Once the project is done, that figure could grow to 2,000 acres, opening up new areas for paddle boarding and boating. It’s undecided whether the area dedicated to power boat use will be expanded.

Castle Pines resident Don Turk took his power boat to Chatfield last week.

“This lake is too small. I’m glad they’re expanding it,” Turk said. The reservoir can get crowded for boaters, he said, and he hopes plans will include expanding the area open to power boats. Boat owners contribute taxes and fees to the state and help create jobs in boat sales, service and other industries, he noted.

“Power boating is an important part of the economy,” Turk said.

The project’s impact on recreation is important, Chatfield Reservoir Mitigation Co. officials said. The park welcomes 1.6 million visitors annually, and collects roughly $3 million in at-gate revenues. Part of a state-approved mitigation agreement dictates that if the park misses revenue projections while construction is underway, the company is obligated to pay the difference to Parks and Wildlife.

Environmental health is also a consideration. Mitigation work to restore wetland habitat along Plum Creek on the south end of the park is scheduled to begin this year.

But the main purpose for the work is to meet water needs, Feehan said. Colorado’s population is expected to balloon to 7.16 million people by 2030 (it was 4.34 million in 2000). Finding sufficient water storage to meet the diverse needs such growth creates has been a concern since the 1990s, project participants say. The reallocation will help alleviate some of that pressure and lessen the demands on subterranean aquifers, a long-relied upon, non-renewable water source. 

“The main reason for the project is storage and being able to use renewable resources instead of non-renewable resources for some of these partners,” Feehan said. “This reallocates space in this existing facility to allow entities in the metro area to store water and help them balance their water portfolio in terms of meeting their long terms water supply needs for their customers.”