Denver Water will move water from Antero Reservoir to Cheesman Reservoir over the coming weeks and shut public access to the Park County stillwater after sunset on May 13, the utility announced April 20. The drawdown is a drought response, triggered by what state and utility records now describe as the worst snowpack year in Colorado’s recorded history.
The transfer will keep about 5,000 acre-feet of water—roughly a quarter of Antero’s storage capacity—from evaporating off the shallow reservoir’s broad surface in summer heat. Antero has the highest evaporation-to-storage ratio of any reservoir in Denver Water’s system. In a normal runoff year, snowmelt replaces the loss. The 2026 snowpack won’t.
Denver Water’s April 27 supply update reported snowpack in the Colorado River Basin portion of its collection system at 18 percent of normal—the worst on record—and the South Platte River Basin portion at 2 percent of normal, the second-worst. Statewide, the Natural Resources Conservation Service put snow water equivalent at 22 percent of median on April 9. Peak snowpack arrived March 8, a month earlier than the median April 8 peak, and 95 percent of SNOTEL sites recorded their lowest or second-lowest values on record by the end of March.
“Antero is a drought reservoir, designed to provide water to our customers during a severe drought,” said Nathan Elder, manager of water supply for Denver Water. “Consolidating this water into Cheesman will help us make the most of the water we have.”
Salvage window through May 13
Colorado Parks and Wildlife has authorized an emergency public fish salvage for the reservoir, effective immediately and running through sunset on May 13. All bag and possession limits on every species are lifted during that window. A Colorado fishing license is still required, and only legal methods of take are permitted. Motorized boating and commercial fishing are not allowed; hand-launched vessels and shoreline angling are.
Antero supports rainbow trout, brown trout, brook trout, cutthroat trout, cutbow, and splake. The shallow, weed-rich basin and dense scud population produce fast-growing, trophy-class trout. Kyle Battige, CPW senior aquatic biologist, said the agency is evaluating its own salvage operation alongside the public effort.
“Colorado Parks and Wildlife appreciates the public’s help in harvesting fish from Antero and utilizing those resources as much as possible,” Battige said. “We are currently evaluating the feasibility of CPW-led salvage efforts and hope to rebuild into a high quality fishery once the reservoir is filled in the future.”
CPW also flagged a biosecurity issue. Antero has tested positive for New Zealand mudsnails, an invasive species that can survive out of water for up to 50 days. Anglers fishing the salvage window must clean, drain, and dry all gear before using it on another waterway.
A reservoir built for this
Antero was the first dam on the South Platte River, completed in 1909 at roughly 8,900 feet in the South Park basin between Fairplay and Hartsel. Denver Water acquired the property in 1924. The reservoir has been drained twice since 2000—in 2002 for drought, when it stayed dry until 2007, and in 2015 for a dam rehabilitation project. A planned 2013 drainage was averted by late-season storms.
CPW has handled both prior drainages. In 2015, the agency corralled fish into the spillway as water exited and trucked surviving trout to other reservoirs in the South Platte system. After the 2002 drainage, recovery took years; CPW restocked Antero with rainbow, brook, brown, cutthroat, cutbow, and splake once it refilled.
The Antero closure is the most visible piece of a broader Denver Water drought response. The utility’s board declared a Stage 1 drought on March 25, asking customers for a 20 percent reduction in water use through April 30, 2027, and approved temporary drought pricing on April 8—the first such pricing since the 2002–2004 drought, according to CEO Alan Salazar. On April 15, the utility announced that motorized boats would be barred from Williams Fork Reservoir in Grand County for the 2026 season because surface elevation sits roughly 13 feet below the threshold needed to open the east boat ramp; shoreline fishing and non-motorized craft remain permitted there.
Denver Water has not set a refill date for Antero. The drought will dictate one.
