Armstrong's Spring Creek Professional Review and Guide
"A controversial berm preserved this bit of dry-fly heaven, albeit for a price. As you stand on the west bank, the Yellowstone is running high, wide, handsome, and brown—brown with meltwater, streaming from the Yellowstone caldera and the peaks of the Absaroka and Gallatin Mountains which form the river’s valley. But in front of you on this late June day is a small stream, little more than 30 feet wide, that’s flowing clear as a soprano’s highest note.
Aquatic grasses sway with the steady currents that trip happily through runs of cobbly rock. Here and there anglers work PMDs for rising fish. That’s where the action is. Fed by a massive spring of cold and constant flows, Armstrong’s Spring Creek fishes well all the time, except when the flooding Yellowstone ploughs across its narrow flood plain and invades the spring creek’s channel. Angling methods: fly-fishing only."