The South Fork of the Boise River may not receive the same attention as other fisheries in Idaho, but it is absolutely worth visiting. In this guide we’ll cover what makes it so special, what species you can expect to find, and some tips on how to fish it.
Introduction to the South Fork of the Boise River
Flowing into Anderson Ranch Reservoir then continuing on to Arrowrock Reservoir where it joins the North Fork, the South Fork of the Boise River offers miles and miles of fishable water for anglers.
While the river can be fished above Anderson Ranch Reservoir, the main stretch is located downstream. This section is roughly 75 miles from Boise, making it a very accessible fishery to those with limited time.
Anglers can expect to find a variety of species, including Rainbow trout, Bull Trout, and Whitefish. There are quite a few big fish throughout the South Fork of the Boise, adding to the appeal.
Best Times to Fly Fish the South Fork of the Boise River
Fishing on the South Fork of the Boise can be excellent any time of year, but if you are interested in a specific species or fishing method it’s important to understand the different seasons.
Summer
For many, this is the most popular time to fish the river. This is when the dry fly fishing is at its best, and the fish are feeding heavily, taking full advantage of the warming weather and water temperatures. Big bugs will begin to arrive during this time of year, and it’s hard to beat fishing a large dry fly.
The river will be higher, which can pose some access issues for wade anglers so make sure to keep an eye on the flows. For those wanting to float the river, this is a great time and will help anglers reach parts of the river difficult to get to any other way.
Fall
Dry fly fishing can still be effective, but fall is a great time to seriously start considering fishing streamers more regularly. Aggressive fish will be very interested in a larger meal which can lead to some fun fishing. Many times fishing a streamer may not produce the most fish, but it is likely to produce the largest.
Weather is more variable this time of year, so be prepared for a little bit of everything and make sure to check the forecast before heading out. Fall also usually means fewer people heading to the river, so you might be able to enjoy a quieter day on the water. It is also a great time to wade the river as the flows will make it much easier than summer.
Winter
Being a tailwater, there is a solid year-round food source for the fish. The majority of the fishing will be sub surface, so it’s recommended to use nymphs in smaller sizes. During this time of year, the fish will be the most sluggish which means you will need to put your fly right in front of their face.
They won’t be as willing to chase or move for a meal. Depth and proper presentation are key for winter fishing. Lower flows will mean easy wading, just make sure to wear layers.
Spring
Spring is always a welcome time for anglers and fish alike. Larger hatches are beginning to occur, and the fish will be taking full advantage of this food source. Spring fishing can really depend on a lot of different environmental factors like weather, water temp, and river flows.
Most of the feeding will still be taking place under the water, but there will start to be more dry fly opportunities, and many times the period just before the closure can be extremely good.
River Closure
Every spring the South Fork of the Boise River closes between April 1st and the Friday before Memorial Day weekend. This is to allow the rainbows to spawn with as little disturbance as possible, helping to ensure a strong future.
The closure is in effect between the Neal Bridge upstream to the Anderson Ranch Dam.
Best Flies for The South Fork of the Boise River
Fly choice is always an important part of the equation when out fishing. Here are some of the most popular flies broken down by type.
Dry Flies
During the summer, large dries like salmonfly and golden stonefly patterns can work well. Late July through September is prime time for hopper patterns.
Spring and fall anglers can expect to use smaller dry flies. Keep an eye out for Blue Winged Olive and Pale Morning Dun hatches.
Some topwater action will be very obvious with large takes and big splashes, but others can be much more subtle. Keep an eye out for any disturbances to indicate rising fish, especially early in the morning and late afternoon.
Nymphs
Nymphing is almost always a very effective way to catch fish. Anglers should make sure to have midge patterns (size 16-20), Pat’s Rubber Legs, Pink Alberts, and some baetis nymph options
Fish different riffles and runs, keeping an eye out for foam lines. Try different weights and depths as you move to different areas, one size does not usually fit all.
Streamers
Standard streamers like egg sucking leeches, wooly buggers, and zonkers ranging between size 4-8 can all be effective. Work the bank and deeper pools with sink tips.
Hooking a protected Bull Trout will be most likely while streamer fishing. If you hook one, land the fish and release it as quickly as possible without removing it from the water.
Special Regulations on The South Fork of the Boise River
While the proximity to Idaho’s largest city may add some pressure, it’s important to note The South Fork of the Boise River is off limits to guides, so everyone there will be fishing on their own. This can add to the appeal, but if you are wanting a guided experience, you’ll need to look elsewhere.
The river is strictly catch and release from December 1st through March 31st and no bait is allowed on the river at any time. Anglers may also only use single, barbless hooks while fishing.
Make sure to review the latest regulations on the Idaho Fish and Game website before heading out. Regulations can change and vary from section to section of the South Fork of the Boise.
Conclusion – Fly Fishing The South Fork of the Boise River
A great option near the city of Boise and Mountain home providing the combination of great fishing and convenience. With the ability to float or wade and the opportunity to fish almost year round, a great experience can be had by any angler.