DENNIS MCKINNEY/Colorado Parks and Wildlife
DENNIS MCKINNEY/Colorado Parks and Wildlife
Former Denver Post outdoors editor Bob Saile wrote the book on fishing the South Platte River and has described the South Platte at Deckers as the best trout stream within one hour of a major city in the U.S. That alone ranks it among the most important to thousands of fishermen.
But when Saile co-authored Fishing the South Platte River and Reservoirs with Blair Hamill in the mid-1990s, the devastating Hayman Fire of 2002 remained an unthinkable nightmare, its ramifications upon the delicate fishery unimaginable. For years after the 150,000-acre blaze, mudslides induced by rain and snowmelt runoff dumped countless tons of sediment from the denuded hillsides into the rocky bed of the Deckers fishery, smothering the river bottom.
As a result, the famous fishery that has attracted anglers for the better part of a century was drastically altered for the worse, trout-sustaining insects essentially eradicated by the burial.
“How is that poor, mutilated stream doing these days?” Saile queried recently upon reading the success story of the river through Eleven Mile Canyon. “Maybe another follow-up is in order on what is surely going to be a long, long recovery for what used to be the most important section of trout stream in the state.”
Like most of the South Platte River, the Deckers section below Cheesman Canyon has seen its share of ups and downs. Along with the upstream reaches of Eleven Mile Canyon, this downstream segment of the river is on the upswing these days. But a full decade after the fire, it still has a long way to go.
“I thought maybe after 10 years that the sediment would pass, but it’s nowhere near where it needs to be,” said Jeff Spohn, Colorado Parks and Wildlife aquatic biologist for the region. “The lower (Cheesman) canyon is holding up pretty well. But once you get down into that Deckers reach – below Wigwam Creek and Horse Creek – there’s still a lot of sediment coming down. It’s definitely making progress, but if you look at the fish data pre- and postfire, it’s nowhere close to what it was.”
The most telling statistics relate to brown and rainbow trout size. In 2001, the year before the Hayman Fire, CPW biologists measured the biomass, or pounds of fish per acre, at 216, with 89 fish measuring greater than 14 inches. In 2010, the biomass fell to 88 pounds per acre, 24 fish longer than 14 inches.
The greatest impact is being felt in the lower portion of the 8-mile unit, where the river flattens out. Upstream, from Cheesman Reservoir down to Deckers, the fishery is rebounding, benefiting in part from trophy trout escaping from the privately owned Wigwam Club separating the two reaches.
“Around Cheesman, the fishery is handling the impacts of the fire really well. The numbers haven’t changed much from year to year,” Spohn said. “Initially, we saw a big decline in numbers right around Deckers, but we are getting closer to where we were. Down below, where the river loses that gradient, the numbers are down significantly.”
Spohn’s sediment studies in conjunction with Denver Water offer hope for the battered stream, however. His research indicates that a flow of 500 cfs below Cheesman Reservoir is enough to push the sediment through Deckers as far downstream as Trumbull. From there, the meandering river demands flushing flows of 900 cfs or more to move the silt in the riverbed down to Strontia Springs Reservoir.
“We’ve been able to do that in some years, just not all the years. The utilities won’t just release a bunch of water when they can’t capture it downstream,” Spohn said. “This year, it sounds like we’ll get those flows because of the work that was done on the dam at Cheesman Reservoir. Because of the valve testing, they have to go up that high anyway. We’ll provide recommendations on when and how to do it.”
A new concern arose this spring when the North Fork Fire sparked in late March near the river, although it’s not expected to affect the South Platte directly. Most of the drainages in the area affected by the fire are intermittent and don’t feed directly into the river.
“One of the creeks in the burn area flows right into Strontia Springs Reservoir,” said Dave Bennett, water resource project manager for Denver Water. “We might get a slug of ash or sediment in our foothills treatment plant. It’s something we can work around but have to keep our eyes on.”