Last Cast on the Firehole

Published November 12, 2006 in OutThere section of Bozeman Daily Chronicle

By Joshua Bergan

YELLOWSTONE NATIONAL PARK, Wyo. — November, to fly anglers, means the end of most insect hatches and the beginning of nothing-but-nymphing throughout the winter.

In Yellowstone, it signals the onset of another long winter. But in the midst of the park's hibernation lies a river with the warmth of an August afternoon, and one last chance to raise trout to the surface.

The Firehole River, which meanders 30 miles from Madison Lake to its confluence with the Gibbon River where the world-famous Madison River is born, is not known for the bruiser trout that inhabit other rivers. The Firehole River, however, is as faithful as any Yellowstone landmark for a good day's hatch and a good day's catch, even on the park's fishing closer in November.

"I think Charlie Brooks called it the strangest trout stream on Earth," said Steve Hoovler, manager of Blue Ribbon Flies in West Yellowstone.

What makes the Firehole so strange is what happens to the water on its journey to the Madison.

"The geothermal activity that keeps the water warm and keeps bug activity going," said Josh Duchateau, a fishing guide at The Firehole Ranch on Hebgen Lake.

On its way to the Madison, the Firehole flows through three of the park's major geyser basins - the Upper, Midway and Lower basins. Water spews from the geysers into the river, accounting for almost one quarter of the river's flow by the time it meets the Gibbon. In fact, the thermal feature Excelsior dumps three to four thousand gallons of steaming water into the Firehole each minute, according to YNP's electronic field trip titled, "Getting into Hot Water". Thus, the temperatures in the river are significantly higher than normal river temperatures, year round.

For example, on November 5, the Firehole was 43 degrees prior to flowing through the basins and 53 degrees after. In comparison, the Madison River below the Ennis dam was 38 degrees that day.

Likewise, the Firehole sees some of its coldest temperatures in June due to melting snow. Typical rivers bottom out in December or January.

Due to the odd temperature fluctuation, some caddis and mayflies that hatch once a year on other rivers, hatch twice in a Firehole year. Other bugs have longer hatching seasons.

"The baetis and pseudocloeon (mayflies) hang on a little longer than they would in the Madison or Gallatin," Duchateau said.

Jim Carter of Greater Yellowstone Flyfishers in Four Corners (about 5 miles west of Bozeman and 80 miles north of West Yellowstone), added that while there still may be some baetis popping on other rivers in November, the hatches won't be like the ones on the Firehole at that time of year.

"Not the numbers and frequency as it will be here. You're not going to go around and have all the fish working like we had here," Carter explained, on the park's final fishing day of the year. "They get keyed."

Due to the abundance of food, the fish thrive.

"The weed life that supports the bug activity and just the enormous amount of bug life that's up there just keeps a good number fish in there," Hoovler said, who personally put in about 30 days guiding on the Firehole this year. "(The fish) have a longer time period where their metabolism is higher."

Bountiful life in the river also provides critical food and nutrition for the park's wildlife during the fall, making it a popular animal hangout.

"There's just nothing like it, as far as the backdrop that you're fishing in," Hoovler said.

Another effect of the geyser water is the elevation of certain chemical and pH levels.

Arsenic, which is lethal to humans, is deposited with the thermal water.

However, rainbow trout thrive in areas where highest levels exist, according to YNP's electronic field trip.

The pH level downstream of the geysers in the Firehole gets up to 8.7.

Levels of 9 can be harmful to fish.

"It's pushing the envelope," Hoovler said.

Before you put the dry flies away, one more opportunity to land some rising fish awaits on the Firehole River.

Said Hoovler: "The bug life, the fish life, the lushness of the river, the weed beds. It's just a really rich, rich place to fish."