The Firehole River

I have been here almost two months, yet have only mentioned the Firehole River in passing.  Anglers know it far and wide, for it is one of the most storied trout streams of the West. Geyser watchers know of it too, for its valley is home to the largest collection of geysers and hotsprings in the world.

Firehole River, below Biscuit Basin

This wild river sits atop the continent, untouched and undeveloped by modern times. Yet, it is accessible to hundreds of thousands of Yellowstone visitors to see and enjoy each year as they travel the Grand Loop Road through Yellowstone National Park.

The Firehole is an incredibly beautiful river. Driving along it, panoramas unfold that simply cannot be captured by camera. Fishing along it, underwater habitat and structure tempt cast after cast to an endless combination of trout lies.

Undercut banks like this one held nice trout through mid-June

The Firehole begins high up on the Madison Plateau at 8300 feet elevation very close to the Continental Divide. For the first half of its length, the river flows through backcountry inaccessible except by foot trail. Up there, it is a typical high mountain stream where annual snowpack creates the reservoir of water to spawn this river. 

Things get more interesting once it comes into view just above Old Faithful at 7400 feet elevation. It begins to flow through geyser basins picking up hot spring runoff rich in minerals. It forms wide meadows that attract Yellowstone’s famous wildlife. A short sixteen miles later, it tumbles into a spectacular canyon before joining the Gibbon River. These two rivers then form the Madison River, a headwater river to the Missouri River that begins another hundred miles north of here.

Midway Geyser Basin pouring over a thousand gallons a minute of hot spring runoff into the Firehole

This is an improbable river. Walking the boardwalks through its geyser basins is like no other place on Earth. For here, the Earth speaks. Geysers spout, hot springs bubble, steam vents fume, expanses of heat-loving bacteria form huge palettes of color as these hot waters flow away to the river. Wading the river with flyrod in hand, it is amazing to see its clear waters flowing over sheets and slabs of volcanic lava laid down by Yellowstone’s last eruption 640,000 years ago. 

Slabs of volcanic lava on the Firehole's streambed

Working at the Clinton River Watershed Council made me a student of watersheds, the science of how land and water work together. Being able to walk the Firehole nearly every day is like a graduate course at Oxford in how watersheds are supposed to work. Land, water, gravity, Earth’s heat, and rock’s dissolved minerals all combine to create a river system full of life.

Wild brown and rainbow trout (rivers here have not been stocked since the early 20^th century) hang in its currents.  Bison and elk graze its meadows. Sandhill cranes and ospreys call its riverbanks home. The mineral-rich chemistry of the water from the geysers and hot springs create a lush aquatic life of bright green rooted vegetation. A proliferation of aquatic insects…mayflies, caddis, stoneflies…provide trout with a full diet, and bewilder the angler figuring out what fly will work on any given evening.

Heat-loving bacteria form colorful mats around the river's hot springs

As watersheds go, the Firehole is not large, just 282 square miles. The Clinton River is 760 square miles; the Au Sable River’s drainage at Mio is 1,361 square miles. But, square miles are just two-dimensional, they don’t account for the elevation change of the Firehole’s landscape.  Stretch the surrounding hills and valleys out flat, and you’d get a far larger watershed.

The river’s perimeter, often a hundred yards wide on each side, is boggy, marshy ground; spongy enough in places to bounce trampoline-like to your step. This cushions snowmelt and rain runoff, slowly releasing it back to the river. It is these physical characteristics that give the river its stability. The Firehole virtually never floods out of its banks. Only a few days each spring are lost to fishing due to a muddy river.

Broad meadows line miles of the Firehole

What are lost to anglers, though, are the summer months. The Firehole’s fishing days are numbered as July approaches, when the water becomes too warm from the geothermals for cold-loving trout. They become lethargic or leave to seek cool refuge in small tributaries. It will be time to give the Firehole a rest until September. Then, it’s time to head for Yellowstone cutthroat trout country in the Park’s northeast section.