SUMMIT COUNTY—A $7 million project that will help boost local water supplies is nearing completion, as construction crews put the finishing touches on the enlargement of Old Dillon Reservoir, above Dillon Dam Road between Frisco and Dillon.
And as a bonus, the reservoir could someday be home to the only golden trout fishery in Colorado, giving Summit County a unique angling opportunity that could be a statewide draw.
The enlargement has been in the works for years as a partnership among local water users and the U.S. Forest Service, which manages the public lands around the reservoir. When water starts flowing into the new impoundment, it will help bolster water supplies for the town of Dillon, which depends in large part on stream flows from Straight Creek, running down along I-70 from its source along the Continental Divide. The stream is vulnerable to pollution threats from I-70. During the 2002 drought, Straight Creek flowed at perilously low levels, sending Dillon officials scrambling to develop a backup water plan that included direct diversions from Dillon Reservoir, as well as water-sharing with Silverthorne.
Other local water users will also benefit, and some of the water could go toward helping boost streamflows in dry years. According to a county fact sheet, the water will be used to meet demands from new growth in Summit County and a variety of other purposes, potentially including ball fields and other recreational open space, wetlands restoration, new community facilities and augmentation of well water usage in the Blue River Basin.
The original 62-acre-foot reservoir was built in 1936 and stored water for Dillon until the town was relocated when Dillon Reservoir was created by Denver Water. With the enlargement, Old Dillon Reservoir’s capacity would be upped to 286 acre feet.
The project includes the following elements:
1) enlarging the existing reservoir from 62 to 286 AF of storage capacity by raising the north and south dams;
2) restoring the outlet from Old Dillon Reservoir to the south to Dillon Reservoir);
3) reconstructing the headgate on Salt Lick Gulch and piping the entire length of the Dillon Ditch to serve the enlarged reservoir;
4) rehabilitating the outlet to Salt Lick Gulch;
5) temporary road access improvements;
6) burying overhead lines around Old Dillon Reservoir; and
7) wetland creation for project mitigation.
The county will pay for about 53 percent of the project, with Silverthorne kicking in about 8 percent and Dillon paying for the rest.
Dillon water manager Trevor Giles said the reservoir could start filling later this month — if there is any water available from Salt Lick Gulch. It's not clear if the stream will have enough water available for diversion. More likely, the reservoir will start to fill during next spring's runoff season.
For the long-term, Colorado Parks and Wildlife aquatic biologist Jon Ewert said that, since Old Dillon Reservoir presents a clean slate, he's considering try to develop a golden trout fishery — the first in the state.
Golden trout are native to a drainages in California like the Kern River. They look a bit like cutthroat trout but with more of a golden color. They aren't be mistaken for so-called albino rainbows that also have a yellow hue, Ewert said.
"It sounds pretty cool … I guess time will tell if it's a good idea or not," said Mountain Anglers owner Jackson Streit. "Just the name might be inspiring for people looking to add to their species list," Streit said.
Ewert said successful establishment of a golden trout fishery could give a little boost to Summit County's fishing economy, drawing people from as far as Denver to try and catch a new species. Since golden trout aren't native, they are subject to any special protections, and Ewert envisions a put-and-take fishery, enabling anglers to take their catch home for dinner.
Ewert said there are quite a few challenges associated with establishing the fishery, starting with getting the eggs from California, which isn't a sure thing. The goldens mostly live in high mountain lakes and biologists have to hike in during spawning season to get the eggs, then pack them out.
If Colorado Parks and Wildlife could get the eggs in the spring, they would be hatched and reared in a hatchery for the summer, then released as two-inch fingerlings in the fall. It take another few years before they reach catchable size.
"It's not something that would be an instant fishery … it would take about three or four years," Ewert said.
Another potential challenge is what might happen to the fish — and angler expectations — in a really dry year, when Old Dillon Reservoir could be drained to near empty. In that scenario, anglers who had been used to fishing for the goldens might get upset and protect the draining of the reservoir.
The key would be educating the public so as not to have expectations set too high, and there may also be a possibility of getting a small pool of conservation water — perhaps 20 acre feet — to ensure that fish could survive the winter, Ewert said.