Beginning in Wyoming at the junction of the Firehole and Gibbon Rivers, the Madison River flows through the most thermally active region in the United States; Yellowstone National Park. The Madison’s confluence with the Jefferson and Gallatin rivers near Three Forks, form the Missouri river. From its head, the Madison flows over 100 miles to its confluence.
Upon leaving the Park, the Madison gathers in Hebgen Lake and joins with the waters of Grayling Creek, Spring Creek, Cougar Creek, the South Fork of the Madison and several other small streams. Hebgen Lake contains trout that can weigh up to 12 pounds and can be fished from the shore or a boat. Even though the river downstream from the Hebgen spillway sees fishing pressure for twelve months of the year, this 2 mile stretch can produce quality trout in large numbers.
This small section of river gives way to a body of water, Earthquake Lake, better known as Quake Lake, which was created on August 17, 1959 by a catastrophic south-western Montana earthquake that registered 7.5 on the Richter scale. Quake Lake offers decent fly fishing for brown trout, which are stocked yearly, along with rainbow trout. The best fishing on Quake Lake occurs in late spring and early summer, and again later in the summer and fall.
The stretch below the landslide dam is called the 'Wasteland' or 'Moonscape' by local anglers because of the flood-water destroyed river banks. Many of the trout below the lake are large and voracious, giving them an advantage in the very rapid water. Downstream the flow is characterized by a shallow, broad, and rapid "fifty-mile riffle," as it has so often been described.