The Firehole River flows north approximately 21 miles from its source in tiny Madison Lake near the Continental Divide. It continues to join the Gibbon River to form the Madison River which is the most famous river in the world. The Firehole River flows through several geyser basins including the Upper Geyser Basin, home of the famous Old Faithful. The Firehole River was named for hundreds of geysers including Old Faithful because the river goes through a huge "hole" (early western name for valley) and looks like it is on fire.
As you might expect, the temperature of the Firehole River below the geysers can average several degrees above that of other Yellowstone streams and can reach as high as 76 or 78 degrees in July. As a result, in the hot summer, fishing in this section is almost non-existent because of the lethargic state of the trout. However, upstream, the fishing is good in the Firehole and also in the tributaries where the trout move seeking the cooler waters.
The stream above Old Faithful is is a great place to fish the Firehole River and there is a huge meadows at Biscuit Basin that provide excellent fishing. At Biscuit Basin, the Little Firehole River and Iron Spring Creek join the Firehole bringing some cooler water with it and some more good opportunities for fly fishing.
Then it continues along the road through several meadows until it comes to a U turn known as Muleshoe Bend before reaching the Midway Geyser Basin. This area is easily accessible from the road and contains browns, and rainbows that feast on the abundant insect populations. Cutthroats however, are non-existent in the main Firehole.
From the Midway Geyser Basin to the confluence of Nez Perce Creek the river continues as a mixture of runs, riffles and boulders punctuated with boulders and meadows with smoother water. This is one of the most productive sections of the Firehole. The strong wind in this region provides a good supply of terrestrials to pass by the undercuts where the trout lie in waiting. From Nez Perce Creek the gradient quickens and as a result the next 3 or 4 miles of the Firehole contains runs and riffles punctuated with boulders.
Easy access is provided by the Grand Loop Road along the entire length of the Firehole except above Old Faithful as the Firehole River flows toward Firehole Canyon. Near the canyon, the Grand Loop Road veers off leaving access to the canyon with another road for approximately 3 miles.The canyon area can be difficult to fish and the trout tend to run smaller.
Fishing the Firehole River:
Along its 21 mile trip, the Firehole offers plenty of opportunity to use dry flies as the entire Firehole is loaded with insect life. In rough water, use a short (less than 20 feet) roll cast, casting over the entire area. Expect a trout on every cast so you will be fast in responding to a hit. Terrestrials can be an important addition to the fly box due to the high winds and the undercut banks as the river flows through meadows. Fish upstream and across, casting the fly near the large undercuts where the current meets the bank. Good fishing in the summer can be had in the tributaries because they harbor plenty of trout that are trying to escape the warm water of the main stream.
Late Spring/Early Summer:
Start with the Blue Winged Olives, and Pale Morning Duns in this season. In the spring of the year, nymphs are a favorite among anglers below the Midway Geyser Basin.
Summer:
Due to the temperature of the river, summer is not a great time to fish the Firehole, but a patient angler can get some rewards in July and August by using the terrestrial patterns.
Fall:
September and October bring a return of hot fishing along the Firehole River due to sound hatches and the migration of the browns.
Access for most of the 21 miles is gained by the Grand Loop Road without too much hiking. Access to the canyon is provided by the Firehole Canyon road.