Flow out of Palisades Dam has leveled at about 4500 cfs for several days, but is certain to rise as weather warms and downstream irrigation demands increase. Tributaries below the dam are releasing discolored run-off into the river.
Still water fly fishers are yearning for so many waters to open and offer good fishing. Here is some info we have gathered on status of the most popular of these.
Ice is leaving Chesterfield Reservoir. See picture above (courtesy of Dave Whitworth) taken last Wednesday. At that date, it was about 80% iced over. Road to the boat dock is open, and ice should be gone for the upcoming week.
Twenty-Four Mile Reservoir is likely totally iced over, and the road to it can be damaged by travel. So it is in best interest to wait until ice leaves and the road dries out.
Blackfoot Reservoir remains iced over. Contact Bingham and Caribou county web sites for road conditions.
The Dairy Creek Road leaving just below Hawkins Reservoir and making a short cut to Daniels Reservoir is open, but rough in places. It is being fished ( mostly Utah anglers) but offers spotty fishing to date.
Hawkins Reservoir has been stocked with hatchery catchable rainbows, and fishing action is picking up.
Springfield Reservoir offers spotty fishing with early AMs and evenings being best time for action. Try midge pupa patterns under indicators at these times.
Ground water flooding impacts access at the Vernon Bridge.
Here is some interesting info from Dr. Van Kirk on the effects of the freshet performed for four days in late April.
Over the four days of the freshet operation, 321 tons of fine sediment were exported from the river reach between Island Park Dam and Pinehaven. Based on pre- and post-freshet numbers, we expect that about 30 tons would have been exported over those four days had the freshet not been done. For reference, the average annual net export of fine sediment from the reach over irrigation years 2016-2022 is 650 tons. So, the freshet moved half of the average annual sediment budget in three days. Freshet-related turbidity has dropped to near pre-freshet levels, but now increased stream flow from natural snow melt is increasing turbidity again, especially in the lower watershed.
Meanwhile, warmer water temperatures are accelerating aquatic insect development, although hatch timing remains later than average and even later than last year over the lower watershed. We expect rapidly warming conditions over the next few days, but the cooler forecast for late in the week could slow down progress toward average hatch timing ( His info on aquatic insect hatches helps explain the relatively slow recent fishing on the lower river).
Rob Van Kirk, Ph.D.
Senior Scientist
P.O. Box 550
Ashton, ID 83420
208-881-3407 CELLG
Our snow-water equivalents (SWEs) range from about 130% of normal in the Snake River drainage above Palisades Reservoir and Henry’s Fork drainage to 375% of normal in the Blackfoot River, Portneuf River, and Willow Creek drainages. These combined with what weather-wise looks like a fairly normal run-off season suggest that the upcoming fly fishing months will abound with cool stream flows that will benefit trout activity. It’s all great news! True, this means streams will be high with run-off a bit longer than many fly fishers would prefer, but getting to such waters may also be interesting. With so much snow yet to come off, back country roads that approach so many of these waters may not become passable until later than normal. So road maintenance agencies ranging from municipal to federal have issued closure statements cautioning the public on traveling such only after they are cleared of snow and dried enough not to be damaged by traffic.
We at Jimmy’s All Seasons Angler will watch both road and water situations and provide on this website information that will help fly-fishers decide which streams to visit and when roads to them are open.
Headlines from Dr. Rob Van Kirk’s SWE report filed yesterday for the Henry’s Fork drainage.
Headlines
• Temperatures and snow melt were well above average yesterday, but current SWE is 10% above the average annual peak and 27% above average for the date.
• Natural stream flow has increased 22% in the past two days and is 72% of average for the date.
• Precipitation over the next week is now forecast to be heavy, with much cooler temperatures.
• My forecast for April-September total natural stream flow is 105% of average for the watershed: 102% in upper Henry’s Fork, 103% in Fall River, and 106% in Teton River.
From the Henry’s Fork confluence downstream flow is increasing because run-off has begun in tributaries and because of the increased flow out of Palisades Dam. The USGS maintained flow graph for the river below American Falls Reservoir looks like a step function as flow is now around 6000 cfs and and will be increasing to satisfy downstream irrigation demands. So look for better fishing days on the river as we warm to where we should for the time of the year.
Flow out of Palisades Dam, now about 3400 cfs, is going up two reasons. First are Magic Valley irrigation demands, and second flood control because run-off from snow melt in upstream drainages is just beginning. Look for the flow of cold storage water to increase and thus have a negative impact on fishing for a while.
Outflow will be increased to 2,000 cfs in four hourly increments this morning and held at 2,000 cfs until at least Thursday and most likely until Friday morning. Post-freshet outflow is tentatively planned to be set at 650 cfs, but the exact figure will be determined by inflow rate. Current inflow is around 500 cfs, but I expect that to jump quickly over the next few days to 800 cfs and likely to exceed 1,000 cfs by the weekend. This will impact flow downstream to Ashton Reservoir and has purpose of helping to flush silt from the river bed.
Rob Van Kirk, Ph.D.
Senior Scientist
P.O. Box 550
Ashton, ID 83420
208-881-3407 CELL
Although the shop will be under new ownership and management by June, we are planning a summer fly casting class schedule. The current weather makes it tough to give a starting date, but we will announce dates, location, fee and equipment suggestion information on this website.
It is the time of year for IDF&G to resume their South Fork Rainbow Trout suppression activity while low flow (1130cfs out of Palisades Dam) prevails. This will take place in steps throughout the river from Palisades Dam on downstream to Lufkin Bottom. Rainbows captured through electro-shocking will be transported to other waters around the region. See the schedule below and see more information on this action on: F&G begins rainbow trout suppression on South Fork Snake River to benefit native Yellowstone cutthroat trout | Idaho Fish and Game.
