The stream flows south out of the Bob Marshall Wilderness Area through western Montana. A marathon of waters running great distances. The waters cling to us long after we’ve cut off the fly and stepped out of our waders to sit with an exhausted grin. Each day away from this stream, I think of these waters, think on them, playing every whit of their great length.

I like to imagine the journey trout make in the hottest days of summer, from the river in the valley rising into the mountains where waters grow colder, narrowing to their source, which of course is our source, too. The blue clarity they assume is akin to what I think the world’s beginning must have been like.

It’s along sections of this stream, in places lined with cedar and chokecherry, with oxbows of alder and willow and the ever-present threat of grizzly, that I return each year. Here, sandhill cranes croak as they fly overhead. A beaver’s tail slaps at our possible threat. Mule deer crash from the undergrowth as we approach the places where they lay in the midday heat. And as the waters recede with the first hint of summer’s drought, we find, in the mud and gravel, mountain lion tracks and bear scat, a wolf’s pad following moose hoofprints.

A few hours into the long walk, there’s a stretch where a pillar of earth stands in the middle of the watercourse, forming a small hydraulic. For more than a decade, this earthen obelisk has withstood spring floods, marking a place where we’ve caught sizeable cutthroat and fat brookies, where bull trout in their prodigious sway wait to attack another fish.

In a memory that feels more dream than real, during the summer before my son Noah married, I walked ahead of him, leaving him to fish a lower bend where a pod of cutthroat was rising. On previous hikes, I’d caught good fish on the far edge of the hydraulic and liked the challenge of mending the line in the fast-moving water, then high-sticking the rest, hoping an aggressive trout might surge from some pocket of stillness on the edge of, or beneath, the swirl.

As I walked by a bank of willows, I noticed an irregular quaking that couldn’t be wind. Lurching to a stop, hand on bear spray, I hollered Hey, bear! four times. The shaking metamorphosed into a dark arm tangled in the branches.

Foolishly I took a step forward, drawn by a dumbfounded feeling of not knowing and wanting to know. Had my eyes, which had begun to fail in my sixth decade, deceived me? A deer or moose would have burst away from where I stood. A bear, with any luck, would have sulked a bit and trudged in the opposite direction, unless there was a fresh kill to protect.

Specks of blood spattered the gravel in front of a slender game path that allowed entrance into the willow maze, revealing a wound that did exist. The arm shook again and transformed into a wing. An eagle materialized before me, shackled to the earth as if in myth. An immature bird, she awkwardly flexed the injured appendage, frame bobbing and shuddering. I retreated, unsure what my role in all of this should be, only to find Noah walking up, eyes wide in disbelief.

Together we ran through possible scenarios: Had the bird been shot and couldn’t fly? Was she tangled in old barbed wire from a time when cattle grazed the meadow? Should we go into the thicket to see if we could free her?

In our confusion and lack of resolve, a shadow crossed over us, moving quickly, and landed in a snag 20 yards away. A mature golden eagle stared at us with territorial aggression, then aimed its gaze at the injured, immature bald eagle.

Before we could place the last pieces of the puzzle, another shadow swooped from upriver, this one with a distinct white head, slamming her body into the golden eagle and displacing him from the snag. Their screams overcame the noise of the waters. The bald eagle chased the golden eagle the length of the meadow until the golden eagle disappeared and the bald eagle circled back to perch in an aspen tree.

We retreated downstream. No reason to be bystanders in a battle we had no stake in. But the next day — because the fishing had been so good and because the parent in me slept with restless concern — we hiked back to the obelisk at the stream’s bend to check on the immature bald eagle. She stood on the sandy spit, no longer taking cover in the willow thicket, her parent nowhere in sight. Upon seeing us, she flew gingerly — as if walking on air with a limp — and landed in the snag where yesterday her tormenter sat.

We weren’t going to get close enough to examine her, but I wanted to make sure she had what she needed to heal. Maybe a meal. Raptors burn calories at an alarming rate. Even if her parent brought fish or rodents or birds, hunting for two is never easy.

Noah tied on a dropper and floated a run downstream where we’d seen whitefish feeding, scales glittering golden along the stream bottom. Whitefish are good eating, and soon Noah had a fat 15-incher on the bank, where he quickly broke its spine.

We walked the fish to where the obelisk centered the stream. Noah, all 6 feet, 5 inches of him, arched his back, launching the dead whitefish into the air. It twirled and hung for a moment, pearly and glistening, then fell with a thud at the base of the snag. The eagle looked at us, looked down at the fish, and waited for us to leave.