The last few feet of draw down of water from Ashton Reservoir should be completed this week. Turbidity in the river below the dam continues because of by-pass tunnel construction which will continue through the week. The river is cutting a new channel in the upper end of the reservoir adding fines to the river below. After draw down and tunnel construction are completed, look for improved water quality in the river below. The Henry’s Fork Foundation (www.henrysfork .org) publishes progress and observation reports on the Ashton Dam construction regularly.
Because of construction activities on Ashton Dam the river below clouds up from time to time. So fishing below the dam has slowed. On the upper river Last Chance-Harriman is fishing well. Morning spinner falls, Mid-day and early evening terrestrial activity and evening caddis activity make for action. Want a chance at a big cutthroat or brookie in the Henry’s Fork? The flow out of Henry’s Lake is being dropped. So fish that have come out of the lake and have survived the summer in the reach known as “Henry’s Lake Outlet”, mostly cutthroat but some hybrids and brookies, will be moving downstream into the Tubs above Macks Inn and eventually down to Island Park Reservoir. Best way to encounter these is presenting streamer patterns from the Tubs on down through Coffee Pot.
We are all greatly interested in effects of Ashton Dam construction on the river below. It appears that water will continue to be released until late next week in order to get the reservoir water level down 17 feet for work to be performed. Therefore look for silt to be released through this time frame and impact river clarity at least as far downstream as the Chester Dam backwaters. So far it appears that released silt is within expected amounts. The Henry’s Fork Foundation (www.henrysfork.org) posts pictures of the river and is monitoring the impacts on it.
On the upper river around Last Chance and the Harriman reach, PMD spinner falls are bringing AM action, and terrestrial insect patterns bring action during daytime hours. Have you ever twitched a hair mouse around grassy banks here around twilight?
The most important event likely on the whole river is construction ongoing at the Ashton Dam and impact on the river below. The best way to keep up to date on construction impact is to go the Henry’s Fork Foundation web site: www.henrysfork.org, and under the Latest News banner click on Ashton Dam Tunnel Tap in Progress.
We have reports of some silt entering the river below from construction activity on the Ashton Dam. It appears that the amount is within expected limits, and if so let’s hope that it stays that way. The Henry’s Fork Foundation is monitoring the river below the dam, and will have good information on effects of construction.
Fishing success on the lower river has slowed as is usual for the time of year. Best chance for action would be to present terrestrial patterns or fish during spinner falls. We also have reports of the same with respect to activity on the upper river during mid day hours. Mornings (try tricolife cycle patterns) and evenings (terrestrial, caddis life cycle, rusty spinner patterns) remain good fishing here.
A tunnel is being blasted to send water around Ashton Dam so construction work can begin there when the reservoir water level is reduced by about 17 feet. Release of water will begin after the tunnel is completed and is certain to impact the river below. As we receive information on Ashton Dam construction and impacts on the river below we will post such information here.
Big news here is that construction will soon begin on the Ashton Dam. To begin, the reservoir will be drained by 17 feet over the near future after an outlet tunnel is blasted. We are all hoping that this will be done in a manner that will not silt the downstream river bottom. Nevertheless with increased flows of warm water, fishing will be impacted downstream likely through the Chester Dam backwater. Terrestrial patterns presented along vegetated banks, outcrops, and overhanging logs should bring interest during daytime. Evening caddis activity should bring action, too.
Flow out of Henry’s Lake has been well over 100cfs all summer, so a lot of large lake fish have been washed into the river below. Yesterday flow out of the lake was dropped to 98cfs. That means those big fish escaped from Henry’s Lake will move downstream. Want a chance to catch a really large cutt, hybrid or brookie? Try the Flat Ranch reach within the next few days. Try streamers or terrestrial patterns for the best chance to encounter these big guys.
Best way to get action up and down the river this part of the season is through using terrestrial patterns. Expect them to work very well in less frequented locations such as Hatchery Ford, above and between Mesa Falls, below Riverside campground, and above and below Coffee Pot Rapids. They certainly will be effective at Last Chance, up and down the Harriman State Park reach, and around Wood Road 16, but you will have more company presenting the same and a greater variety of life forms for fish to choose from.
Action on the lower river has slowed as is typical this time of year. With hoppers coming on, and ant and beetle pattern having been effective for a while, we have to suggest that you concentrate on presenting these. If not, try small bead head nymphs. Don’t forget that streamers at twilight can bring out that big guy.