An interesting thing about The Nature Conservancy’s major renovation project on Silver Creek is you may not notice it.
When the native vegetation takes root and flourishes, it will look like a natural part of the creek.
“We tried to mimic what it used to look like,” said Dayna Gross, conservation manager for Silver Creek Preserve south of Sun Valley, Idaho. “And I couldn’t be happier with the way it looks.”
Part of what makes the world-famous stream special and unique is spring water that feeds Silver Creek is about 60 degrees year round, where it bubbles out of the ground upstream in Stocker and Loving creeks.
That cool water provides ideal habitat for trout, as well as the insects they feed upon.
But when that cool water feeds into a shallow pond at Silver Creek Preserve, summer heat warms it before the water continues downstream.
Hot summer, warm water
Conservancy officials have known for decades there’s a problem having that large, shallow pond above and below Kilpatrick Bridge.
Gross said that during the summer of 2012, a gauge about 5 miles downstream measured 100 days of temperatures over 68 degrees, which is unhealthy for trout, and 40 days of water temperatures over 80 degrees, which is potentially lethal to trout.
Add to that a barrier from a dam that blocked fish migration, and the creek was one hot summer away from a major fish kill.
Doug Megargle, Idaho Fish and Game’s regional fish manager, said there’s been fish mortality in the past, and if it wasn’t directly caused by warm water, “it certainly indicated stressful conditions.”
In cooperation with the Purdy family, who owns the land immediately downstream, the Conservancy planned to dredge the pond and restore the stream channel, and also use the dredge fill to build islands and peninsulas to shrink the pond. Restoring the channel would also create more current and push sediment downstream during high water.The dam on the Purdy property was altered so it could release cooler water, and a fish ladder was installed.
The timing of the project coincided with low water this year. The area received about half its average precipitation.
When the Purdys opened the dam and drained their pond, the current increased upstream on the preserve and scoured the channel.
It also dried much of the pond and allowed the crews hired by the Conservancy to bring in heavy equipment to recontour the bottom land and create a back channel and wetland.
Being able to accomplish all the work this spring meant the Conservancy won’t have to close access to a portion of the creek after Labor Day, which was part of the original plan.
Next Chapter unwritten
Part of the challenge of this project is, despite studies, there’s no guarantee what will happen.
Gross said she doesn’t know how much cooler the creek will be downstream, if any.
“I would be happy with a 5-degree change downstream,” she said. “If we had that big of an effect, it would be awesome.”
Megargle is also taking a wait-and-see approach.
“Based on modeling, I’m hopeful,” he said. “I think we will see a benefit, but to what extent I don’t know.”
The creek has abundant trout, and the unique ecosystem provides an oasis of habitat for everything from fish to songbirds to moose.
According to the Nature Conservancy, Silver Creek has some of the highest densities of stream insects in North America, and as many as 150 species of birds have been identified on the preserve.
While it is a popular place for nature watchers, they’re typically outnumbered by anglers drawn by the creek’s international reputation as a fly fishing mecca.
Anglers won’t likely see much difference in how the creek looks and feels unless they’re favorite method of fishing is float tubing above Kilpatrick Bridge. In that case, there’s less water to fish.
But Gross said the original plans to further restrict the stream channel were dialed back so people could still fish from float tubes.
Megargle said he didn’t hear a bunch of complaints from float tubers after fishing season Memorial Day weekend.
The changes are also unlikely to affect the creek’s famous brown drake hatch, which has already started. Spring water temperatures aren’t likely to change enough to alter their timing.
Later in summer, it’s possible that insect hatches, or their timing, may change because they are temperature sensitive.
Gross said U.S. Geological Survey’s scientists are studying the creek’s insects and hoping to record any changes if they occur and monitor the effects of the project.
For those concerned about the scenery, Silver Creek’s famed meanders through the willow-lined meadows remain. The stately cottonwoods still sway in the summer wind, and you can still spot big trout cruising in the translucent pools at Sullivan Slough. The mountains still loom in the distance, and you can still sit on the deck of The Nature Conservancy’s visitors center and enjoy one of the best views in Idaho.
Don’t forget to sign the guest log, and maybe leave a donation. The work done to protect Silver Creek didn’t come easy or cheap, although you may not notice it because it blends with the natural and unspoiled scenery.
And that’s how the folks at the Conservancy want it.