No significant change in any way since our last report. Flows are about constant at higher than normal amounts to meet irrigation demands and to place a useful amount of water in downstream reservoirs. Stream-side terrestrial insects are increasing making “hopper-dropper” combos increasingly effective. Rubber leg patterns are good droppers, best hopper patterns are numerous. Proper presentation is more important than pattern selection.
Same story: fish creek mouths and spring holes. Get there at sunrise, fish till mid-day and expect company especially if you are catching fish. Opportunistic anglers will use binoculars to glass the lake and join your success. Again refer to Bill Schiess’s “Fishing Henry’s Lake” to find the best mid-summer patterns. .
Here are excerpts from Ron Van Kirk’s July 27th analysis of the Henry’s Fork drainage water status. We offer these for those interested in the drainage water situation and its impact on fishing during this dry summer and for those planning a visit to any of the drainage’s major waters. Henry’s Fork fishing conditions have changed little since our Saturday, July 24th fishing report. Anywhere you fish the river, be sure to have terrestrial insect patterns in your fly box!
Details:
Mean temperature yesterday was 7 degrees F above average and the warmest since last Monday. The daily maximum was the warmest since Sunday the 18th. Water-year precipitation to date is still 75% of average. Forecasts are becoming more confident in widespread, wetting rain beginning tomorrow and continuing for at least a week. The current seven-day forecast calls for widespread rainfall totals of at least 1 inch, with up to 3 inches possible on the Yellowstone Plateau. Temperatures will gradually cool to average—something we have not seen since late May. Outlooks at the time frame of 7-14 days give greater-than-even odds of above-average precipitation, something we have also not seen since late May. Overnight low temperatures will increase with the increase in moisture, but daytime highs will cool substantially, reaching 8-10 degrees F BELOW average by early next week.
If the forecast rainfall totals materialize, streamflow will increase substantially by this time next week, especially in Fall River and Teton River. Precipitation of 1-3 inches in headwater areas could increase natural flow by 50% or so, at least briefly bringing natural flow up to average. That much rain would also directly add 500-1000 ac-ft to the surface of Island Park Reservoir, on top of any increases in stream inflow. In addition, an extended period of rain in valley areas would decrease irrigation demand, although that may come at the cost of damage to cut hay and to ripening grain. The duration of precipitation is a critical determinant of the latter—if valley rain is concentrated in a narrow window of a day or two followed by a return to dry weather, grain will dry without sprouting on the stalk. An extended period of rain, such as we experienced in August of 2014, could result in widespread loss of grain crops. The best scenario for both water supply and crop quality is 1-2 days of rain in the valleys, with daily showers in the mountains over an extended period. Right now, that scenario is essentially what is forecast.
For now, natural flow remains very stable at 68% of average: 76% in upper Henry’s Fork, 68% in Fall River, and 57% in Teton River. Diversion continued to drop yesterday and is 77% of average: 81% on Henry’s Fork, 64% on Fall River, and 79% on Teton River. The difference between irrigation demand and natural flow has dropped to only 100 cfs, about average for this time of year.
As expected, natural flow water-rights priority has continued to drop and was at 7/10/1889 yesterday, which reduced available natural flow on several canals in the watershed, prompting further reductions in diversion. However, the upcoming rain will increase natural flow enough that some of the natural-flow rights cut over the past week or so will at least briefly come back into priority next week, allowing more diversion without storage charges to those water users.
As I mentioned yesterday, water management over the next few weeks will be determined by a complex combination of water-rights availability, hay prices (very high right now), and effects of rain on streamflow, crop development and harvest. After two months of very stable albeit hot and dry conditions, August is promising to start off with a little more excitement for us water-data geeks. That said, no long-term changes to drought conditions are expected. Keep in mind that while the heavy rain we received at the end of May temporarily helped fill reservoirs and lowered irrigation demand, it had essentially no effect on drought conditions, which are worse now than they were in May.
Continued decreases in diversion have allowed continued cuts in Crosscut Canal delivery to the Teton River and resulted in increased streamflow in the lower Henry’s Fork. As a result, outflow from Island Park Reservoir was decreased to 915 cfs yesterday, and that decrease is just making its way to the lower watershed this morning. For the 47 days of Island Park Reservoir draft so far this season, streamflow in the Henry’s Fork downstream of all diversions has averaged 342 cfs, compared with the target flow of 350 cfs. The coefficient of variation in daily flow is 30%, meaning that the typical daily departure from the average is around 100 cfs. Outflow from Grassy Lake will be cut to zero this week, further reducing reservoir draft. If the rain materializes as forecast, it is possible that we may even have a few days next week when total reservoir storage in Grassy Lake, Henry’s Lake, and Island Park combined stays constant.
Island Park Reservoir is 51% full, compared with 73% full on average and 42% full in 2016. Total storage in the three reservoirs in the Henry’s Fork watershed is 68% of capacity, compared with 81% full on average and 64% in 2016. The three reservoirs currently contain over 9,000 ac-ft more than on this date in 2016.
Rob Van Kirk, Ph.D.
Senior Scientist
P.O. Box 550
Ashton, ID 83420
208-652-3567 OFFICE
208-881-3407 CELL
208-652-3568 FAX
With flow out of Mackay Dam around 150 cfs, wading is quite easy. Some PMDs and western green drakes with PM caddis are emerging, so life cycle patterns will produce. Traditional attractors such as renegades, Wulff series patterns, stimulaters, and humpies. Terrestrial insect are coming on. With the Conservancy’s Silver Creek closure and the low flows in the Wood River drainage, visitors are arriving here and along Copper Basin waters.
Flows have been nearly steady at !6300 cfs at Irwin (16500 at Heise,12200 cfs at Lorenzo). All these are a few thousand feet above normal for this time of the season. Fishing from a boat or raft is the way to enjoy the PMDs, pink alberts, sallyies and on the upper river a few remaining stone flies. With the somewhat high flows wading can be a bit treacherous. There are plenty of boating anglers, but by early evening most have gone making the river and launch sites a lot more tranquil. With terrestrial insets, especially hoppers coming on, another item will be added to make top water fishing even more rewarding. Don’t overlook hanging a rubber leg pattern from that high floating hopper pattern.
Bear Gulch
It is time to try terrestrial patterns on nearly the whole river above St. Anthony. Catching and releasing will be toughest on fish from Ashton Dam downstream. From Ashton Reservoir to Warm River as well as the Cardiac Canyon section provides the best fishing on the lower river. You will find the Cardiac Canyon section to be the least crowded section because hard sided boats are not legal ( rafts and flotation devices only) there and walk-in fishing is pretty much the name of the game. Flow out of Island Park dam is down to near historic levels and top water fishing below has picked up. Bead head nymphs are producing in Box Canyon and any pattern the size of a hopper or golden stone fly will also bring action there, but be tolerant of recreationists.
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High-water temperatures and low stream flows prompt fishing closures in Yellowstone National Park
MAMMOTH HOT SPRINGS, WY – Effective Saturday, July 24, Yellowstone National Park’s rivers and streams will close to fishing in the afternoon and evening due to high-water temperatures and unprecedented low stream flows. This closure will protect the park’s native and wild trout fisheries.
What will be closed?
What will be open?
Water temperatures have exceeded 68 degrees Fahrenheit (20 degrees Celsius) in recent days, and flows on many rivers are approaching historic lows. These conditions are extremely stressful and can be fatal to fish. The extended forecast calls for continued hot and dry conditions with a slight chance of isolated afternoon thunderstorms, which contribute to continued low stream flows and high-water temperatures.
Anglers: Please fish during the coolest times of day and land fish quickly–do not play hooked trout to exhaustion. Gently handle fish in the water as much as possible and let them recover before release . Your cooperation will protect the park’s fisheries and may preclude the need to prohibit fishing at all times of the day on some rivers and streams if conditions worsen.
Aldous Lake
Aldous Lake is known mostly to area anglers, and it has enough advantages to be considered for a visit. A mile and a quarter walk up a well maintained trail to reach it keeps out many visitors. Cutthroat trout ranging to trophy size are it’s only salmonid inhabitants, and it is in a scenic setting. Submerged springs keep its water temperature at ideal levels for trout activity. Its only disadvantage is that its shoreline is almost totally timbered (excepting a small portion on its west side). Nevertheless for the fly fisher willing to pack a flotation device from which to fish, the reward for the next several weeks will be gulper activity as speckled dun mayflies emerge during morning and mid-day hours. Action on this rather small lake may not be as dramatic as that on encountering Hebgen Lake’s Madison Arm gulpers, but it certainly is more tranquil. Aldous Lake sits on a bench on the Idaho side of the Continental Divide. From Kilgore, Idaho head west briefly on Antelope Valley Road to East Camas Road. Follow it north to Cottonwood Creek Road, and from it take USFS Road 027 to the Aldous Lake Trailhead.
Now that the giant stone fly event is mainly “in the rear view mirror,” Hebgen Lake’s Madison Arm gulpers are the big attraction.This strictly morning event will attract a lot of action hungry fly fishers, but it is good to remember that other lakes have gulper activity. Elk, Hidden, Cliff and Wade Lakes are good candidates to find this activity.
Here are new emergency closures recently posted on the Montana FWP News web site. See below.
Emergency Fishing Closure will be in effect on portions of Red Rock Creek from Upper Red Rock Lake to the Hell Roaring Creek crossing at South Valley Road. Flow at USGS Gage 06006000 Red Rock Creek above Lakes have fallen near and below 5th percentile mean daily flow. Flow on July 14 was 24.2 cfs (19.7 cfs as of 7/20 10 AM). Low flows have concentrated Arctic Grayling into isolated pools, making them extremely vulnerable to angling. This river section will remain closed to fishing until lifted by FWP administrative action when mean daily flows are adequate to provide cover for Arctic Grayling, or until October 15. The entire Madison River in Montana now has a hoot owl closure
See the FWP NEWS web site for hoot owl and other southwest Montana fishing closures.
Beula Lake
Main roads are crowded with record numbers of tourists and most streams are warm and at or near base levels. There are some waters that do not experience the crowding found on road-side waters and retain water temperatures suitable for active trout. Beula Lake,at near 7500 feet elevation, is one of these if a 2.5 mile walk to get there is not a physical obstacle. It’s trailhead is off the lightly traveled Ashton-Flagg Road near the east end of Grassy Lake Reservoir. Currently it is offering good fishing for those carrying a lightweight flotation device or those willing to wade its southeast and east shore lines. Yellowstone cutthroat trout are the sole inhabitants and they range to near trophy size. Speckled dun, damsel flies and cinnamon caddisflies are the most numerous aquatic insects with leeches and scuds also important. Terrestrial insects become more important as summer advances. Three primitive campground are along the west shore and can be reserved through the park’s back country permit system. Riddle Lake, sitting very near the Continental Divide and off the park’s south entrance highway with a walk of just under 2 miles is similar to Beula in many respects but offers smaller cutthroat.