Why thousands of trees at Chatfield State Park are being cut down
The long-planned removal of popular cottonwoods with their bases flooded by rising waters will improve safety and keep dam from clogging
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CHATFIELD STATE PARK — Thousands of flooded cottonwood snags poking out of the reservoir at Chatfield State Park are popular with anglers and paddleboarders, but they must come out for boater safety and to keep dam outlets from clogging.
Fans of the much-visited lake park southwest of Denver will see nearly 3,000 trees with their bases currently underwater cut down and trucked away in coming months.
Thousands more trees will get the fatefull blue paint marks for removal next year.
Why do the cottonwoods and willows have to go?
Rising water levels for the past couple of years (more about that below) have flooded and eventually killed thousands of cottonwoods and willows that were previously offering shade at the waterline. State and federal officials knew this would happen when a planned reservoir-expansion project began in 2014.
After letting the public play in and around the dead trunks for a few years, it’s now time for them to go. High winds can easily topple trees made unstable by flooded, rotting roots, endangering boaters or people walking the shoreline. In winter, the trunks get frozen into ice floes and further destabilized when wind moves the ice.
The fallen trunks, limbs and roots also drift northeast toward the dam and clog outlets for the South Platte River heading into Littleton and Englewood.
Fishing boats love cruising the shadows and cover provided by the dead trees and fallen trunks, while paddleboarders find them a steering challenge and an exploration opportunity.
“We have enjoyed having the cottonwood and willow trees in the reservoir for the past two years and been pleased by the new recreating opportunities the trees provided our visitors,” Colorado Parks and Wildlife Chatfield Park Manager Kris Wahlers said. “We explored all options to keep the trees, but since they did not survive, we have to do what’s best for our visitors.”
Why has the water been rising at Chatfield?
Colorado’s growing Front Range cities and water agencies are always looking for new reservoirs or expanded, innovative storage ideas for water rights satisfying local demands.
Chatfield was finished in 1975 as part of the U.S. Army Corps of Engineers Tri-Lakes flood control project that includes Cherry Creek State Park and Bear Creek Lake reservoirs. Chatfield can hold 350,000 acre-feet of water but past water levels have always been a small part of the overall basin. The Chatfield Storage Reallocation agreement in 2014 allows local agencies to store up to 20,600 acre-feet in the flood control pool for municipal uses.
Favorable snow and rain in the spring of 2023 finally allowed the partners to store enough basin runoff to reach the extra 20,600 acre-foot level. (An acre-foot can supply the water needs of two to four metro households for a year.) More precipitation in 2023 and 2024, as well as relatively cool weather during key water use seasons, has left the Chatfield pool at or near the maximum levels, keeping the trees flooded.
Who owns the water at Chatfield?
The Army Corps controls the flood-prevention pool. Various water agencies and farm ditch companies see their South Platte River Basin water rights flow through Chatfield. The primary entities taking advantage of the new storage available at Chatfield include Centennial, with nearly 7,000 acre-feet; the Central Colorado Water Conservancy District, a farming district, at nearly 4,300 acre-feet; Denver Water at 1,600 acre-feet; and Castle Pines North district at 1,000 acre-feet.
Does losing the trees hurt the park overall?
Losing thousands of highly visible tree trunks from the northern boat ramp all the way down the western shoreline of the reservoir will certainly make an aesthetic difference for parkgoers. But the mitigation for this year’s big tree cutting began years ago, with plans to replace the shoreline shade and wildlife habitat with thousands of new trees and shrubs.
That planting work began as early as 2018, state parks officials say, with more than 100,000 new trees and shrubs now in the ground. The state says many of those new groves are already thriving and creating cottonwood habitat.
Tree snags at the waterline can be popular with eagles and other nesting birds, but state officials say there were no eagle nests established in the areas that must be cut down.
Will the state park stay open during all the lumberjack work?
Yes. The state says impact on visitation and use will be minimal. About 2,700 tree trunks will be removed over the next six months, followed by a second phase in winter of 2025 with about 2,300 more cottonwoods needing to go. Work will begin this fall at the north boat ramp and move south down the western shore of the reservoir.
Helicopters will be used to grab trees that can’t be reached by workers wearing waders, and for winter tree removal for trunks surrounded by ice.
“To lessen impact to park visitors, one day-use area will be closed at a time while ground crews complete their work. Helicopter work is expected to start after Thanksgiving,” a parks release said. Visitors looking to use a particular area can keep up on closures at the park’s website or social media channels.
