Dillon Reservoir: How’s the fishing?
August 18, 2009
SUMMIT COUNTY – For all its beauty, Dillon Reservoir isn’t exactly known as a hot spot for fishing. In fact, some anglers recently voiced their frustration about the state of the fishery in strongly worded letters to a committee that oversees recreation in the reservoir.”One guy sent an extremely belligerent tirade … People are passionate of their fishing,” said Neil Sperandeo, manager of recreation for Denver Water.”There was a lot innuendo about how everyone is messing up,” said county open space director Brian Lorch, who also serves on the reservoir recreation committee. “It had been years since we had any report from the Colorado Division of Wildlife, so it seemed like a good time for an update.”Based on the concerns expressed by the public, the Dillon Reservoir Recreation Committee asked state wildlife officials for an update on the fishery.”We rely on the Colorado Division of Wildlife to manage fisheries,” Sperandeo said.The job falls to Jon Ewert, a Hot Sulphur Springs-based aquatic biologist for the state who covers Summit County. Ewert assesses the fishery in Dillon Reservoir every couple of years by setting nets, then counting and measuring fish.Responding to the questions from the public, Ewert recently gave the committee a presentation on the state of the fishery in the reservoir.It’s important to remember that the reservoir is managed primarily as a source of domestic water, Ewert said, explaining that strict water quality standards limit the amount of organic material in the reservoir.The crystal-clear water is desirable for that purpose but doesn’t necessarily make for the best habitat conditions for fish. Aquatic plant life and microscopic organisms form the base of every aquatic food chain, and those elements – by design – are in short supply in Dillon Reservoir, he said.For the most part, the water also remains relatively cold year-round, another factor that limits the growth of fish.”The bottom line is, Dillon is not a productive lake,” Ewert said. “Millions of dollars have been spent to keep the water quality high, and the fishing suffers because of that.”On the upside, Ewert said there is a robust population of wild brown trout in the reservoir, probably because there are three high-quality tributaries where the browns can spawn – the Snake River, Ten Mile Creek and the Blue River.But they are skinny and tend to stall out in their growth because of the lack of biomass in the water, he explained.Ewert said a population of wild Kokanee salmon is another indicator that the fishery in the reservoir isn’t completely moribund. Kokanee haven’t been stocked in 30 years, and they only live about four to five years, so they are obviously reproducing successfully, he said.
In a recent effort to improve the fishery, the wildlife agency collaborated with Denver Water and other partners, the state wildlife agency also stocked the reservoir with thousands of Arctic char, a species that thrives in cold water.”One thing people don’t realize is that 70 to 80 percent of the fish population (in Dillon) consists of suckers,” Ewert continued, referring to a species of fish that isn’t exactly prized by anglers.”We’d have a much better fishery if we could reduce that number,” he said.Ewert said there are a few options for reducing the number of trash fish, including the introduction of lake trout.”But they’re voracious predators. They could outstrip their food supply,” Ewert said.Another option that’s been tried elsewhere is to introduce a hybrid fish called a splake, a sterile cross between brook and lake trout.Ewert said he’s due to assess the reservoir’s fishery next summer and will consider various ideas to improve the fishery during the next couple of years.”It’s not that we don’t want the fishery … We’re trying to increase it,” said Dave Fernandez, on-site reservoir manager for Denver Water. “The thing is, it’s not even listed as a fishery,” Fernandez said. “There are a few people catching big fish, but not very many.”Overall, I’d say the fishery has improved a bit in the last 10 years. I’m going to support whatever plans Jon (Ewert) develops,” Sperandeo said.”Things are better than might be expected in Dillon,” Lorch said. “But the fish are deep. Sampling shows that the fish are there, but not where the fishermen are,” he concluded.