Houser and Holter dams on the Missouri were completed in 1911 and 1918. Island Park dam on the Henrys Fork was completed in 1947 creating the Henry's Fork of the Snake as we know it today.
All of those dams dramatically changed the nature of the fishing immediately downstream. Clark Canyon dam South of Dillon was finished in 1964 which almost over night created the fabulous Beaverhead River. Yellowtail on the Big Horn was completed in 1967 although it wasn't until 1979 that it's famous fishing actually started. The early burgeoning years of fly fishing popularity in Southwest Montana were mostly about Yellowstone Park, the Yellowstone River and the Madison, at least at first. But the new tail water fisheries gradually bloomed as a major focus of interest too, particularly so from the 1960s on.
Tail water fishing is so similar to spring creek fishing many consider them slightly different versions of the same thing. In both cases their waters tend to be flat slow moving and crystal clear. Because both spring creek and tail water flows are largely insulated from violent spring snow melt events, aquatic insect populations proliferate and bloom.
The big tail waters and even the little ones like the Beaverhead are a lot like bigger spring creeks. But there are differences. On most tail water rivers there is a huge amount of water too deep to get to on foot. There are plenty of places to wade if you know where to go. If you don't have a boat it's best to find one or two good places to fish and then to slow down and wade carefully. Slowly. Take your time. You're going to spend the day there. In that scenario you do end up with a small chunk of watery real estate you can treat like your own little spring creek. In between marauding drift boats anyway.
If you are a local with a boat of any kind you can float short and anchor up a lot. That way you'll get access to the deep water off limits to wading only. You can still spend most of the day outside of the boat while fishing your own private water. If you fish with small flies, wet or dry, you might put a few fish down with a bad cast but they'll soon come back again. You've got all day.
I remember one late October day on a short tail water float when my wife and I anchored up in an eddy not far from a high bridge. Baetis were hatching and my wife caught seven fish on dry flies without ever standing up. I rowed over to the edge after that and we spent several hours poking at a few hundred yards of river bank. Then we stopped and fished at the edge of a rolling run on the other side of the river just downstream of the high bridge. When it came time go we shifted gears and drifted non-stop the rest of the way in, trolling the main-stem currents with streamers instead of fishing more carefully as we had earlier. Those are the floats I like best. Short and relaxed, almost in slow motion. With a little of everything thrown in.
Long floats are fun too. For better or for worse most guiding scenarios usually involve a long float, like all the way down to the Fourteen Mile Access on the Big Horn. Even on long trips you can still try to slow down and fish carefully at a few selected locations, which might be pods of dimpling fish, and then mostly drift in between. Or you can row a lot, doing your best to fish the whole way down where most of the day's casting opportunities move by in a rapid fire one chance only parade of holding spots, a little like shooting at plastic ducks with an air rifle at the county fair. Spring creek strategies like changing flies for individual fish don't make sense. On days like those No-hackle dry flies or sparsely tied Paraduns are a bit too hard to keep afloat. If you are fishing dry flies you're better of with something that floats better, like bushy-tailed Sparkle Dun. If you aren't tossing streamers or drifting bead heads anyway.
Knowing the water well counts most of all. Perhaps that's always true but freestone rivers like the Yellowstone do change every year at high water. And then they drop every day. All summer long. New channels emerge while others disappear. On the tail-waters topography doesn't change much from year to year. I remember one tail water day when I noticed a school of flashing fish sides over a seam of gravel bottom, in between weeds. I anchored up, put on a heavy bead head and had good fishing for about fifteen minutes. And then it was over. I always check that gravel seam now. Even when those fish sides aren't flashing it's still a good spot. It's always there. Year after year.
On another trip with my buddy Randy I snagged an experimental fly on a willow branch, on a steep bank adjacent to a huge canyon like pool. I anchored up in an eddy where Randy could fish from the boat. I wanted that fly. It was a bit of a thrash to retrieve my fly but I got it. The bank was extra steep. I found myself looking down on a school of about 30 rainbows at the top end of a big slow eddy with their noses not too far from faster water passing a vertical rock cliff wall. It was pseudocleon time in late summer. Pseudocloens are tiny Baetis like mayflies so small the fish don't get particularly interested.
The two biggest fish in a pod of thirty maintained a brotherhood dominating the upstream end of the pod. A parade of pseudocloen duns drifted by. They were mostly ignored. Every once in a while one of the bigger fish near the upstream end of the pod would rise up slowly to intercept a drifting dun and swallow it. So many naturals drifted by unmolested it seemed the few rises that did happen might have been a boredom response. The rise forms were interesting. Not one of those fish swam much at all in order to intercept a drifting mayfly. This had to be an air bladder manipulation. They made their decision to rise up seconds in advance. They rose up dead vertically, slowly without undulating their bodies. And then sank vertically back down again, slowly without moving a muscle it seemed. What really struck me was how deep these fish where. They were rising up a good 36" inches from their holding postures to sip a fly. They may well get a good last minute close up look at a drifting mayfly right before sipping. But they clearly had made their decision to rise up three or four seconds in advance.
Every once in a while the two biggest rainbows at the upstream end of the pod would bolt down stream fifty or sixty feet and then swim back and forth a bit, sometimes shaking there heads in the weeds. I remember thinking this must have been scud foraging behavior. The instant they were gone smaller fish from further back in the pod took over their ruling class lairs at the front of the group. Then the big ones came back again and everybody shifted and settled back to a more familiar, predetermined pecking order. The biggest fish in a pod are not always at the upstream end of the group. But almost always.
When the fish are more interested, perhaps when it's Baetis or PMD time, they don't rest three feet down in between intermittent rises. Interested actively feeding fish lie right below the surface tension, gently swimming if they have to in order to maintain a fixed feeding position at their spot in the sipping order. Pods of rainbows move into shallow soft spots near the edges of the river in order to intercept every possible mayfly while still maintaining their size-dependent sipping order with the larger fish up front, taking first pick. The minute the hatch switches off they leave those soft shallow spots at the edges and head back to deeper lairs best penetrated by nymphing techniques.
Thick mayfly and caddis hatches make our tail water fisheries the popular destinations they are. But even in Summer there aren't always many mayflies to be had. My good friend and fishing buddy Chuck Tuschmidt called me early one July. He was closing in on 70 years old. He and Dan Gard, both long term guides on one of our most prominent tail waters, had decided to retire. Chuck wondered if I would bring a boat up North and give him and Dan a guided send off. I would row all day while he and Dan fished their butts off. As if they were clients. On the 4th of July.
The river was insanely crowded that day. Mid Summer on the tail waters is always busy but this was the fourth of July. There must have been 100 rigs parked at the put in. Chuck looked at Dan, laughed and said "Weak side of the river!" I wasn't even sure what that meant. Once the rowing started the idea of me rowing all the way went over the side of the boat, almost right away. We shared the rowing all day long, but we stayed on the shallow weedy side of the river the whole way.
Where ever a river makes a turn the current tends to move more quickly and pile up on one side of the river while tapering off to a shallower and slower moving flow on the opposite side. On freestone rivers the weak side of the river is often tapered barren and thin over a silt or gravel bottom. On tail water rivers, especially so for the big ones, the weak side of the river can appear as 6" inches to 24" inches of crystal clear water over slowly, gently wafting water weeds. At first glance water like that looks completely barren. You can see right down to the weeds with not a fish to be seen. But fish there are, by the hundreds. They're all hiding in the weeds below. On that day, with two rowdy retiring fishing guides, we had our own half of the river all to ourselves.
All day long immediately across on the strong side of the river a non-stop 4th of July parade of drift boats pounded the banks with bead head bobber rigs. A few Pale Morning Duns did hatch on queue centered around noon, but the few good mayfly slicks were held hostage to a swarm of boats. We stayed put on the weak side of the river. We wacked'em all day long, mostly drifting big bushy dry flies or medium sized wets. Fish come up out of no where, from their weedy hiding places, to blast big attractors. Now that was a fun day. I learned something too. I have a favorite spot on one of my local tail waters on the North side of the river maybe a mile upstream from the takeout where the same pod of rainbows has lived more or less forever. I've been fishing there for thirty years. How long do rainbows live? Three to maybe six years? That group is still there so I must be seeing great grand children of great great grand children. The two or three biggest fish in that group are always at the upstream end. That pod used to be thirty fish strong. Now they're down to less than twenty. But they're still there, seldom more than fifty or so feet away from what seems to be their favorite spot. At the upstream end of their territory a fast current separates them from the next gang upstream. Downstream a ways gets shallow and weedy. They have a territory and it's all theirs. Thirty years? That kind of stability doesn't exist on the big freestone rivers.
On low water years good holding spots can become few and far between, even on the big tail water rivers. At times like those drift boats tend to anchor up and gang up at the heads of the pools where fast shallow riffles dump down onto deeper water. That might be where the most fish are but on low water years the heads of the pools are a frustrating strategy, because they are all too often already taken. At times like that it's often a better strategy to swing wet flies or small streamers at the tail ends of the pools, where deep slow water first starts to shallow up and become faster. Those tail-outs are always good places to fish. They almost always available too.
Dimpling pods of rainbows or hungry individual brown trout feeding on small aquatic insects are the primary reason tail water fisheries have become so popular. But it isn't always all about small flies. In March big fish can be found in what locals call Winter Water, which is relatively deep water with a slow, barely moving current over a gravel bottom, rather than stagnant water over silt. We fish streamers there in late winter, but most locals don't strip them. You drift them deep and slow with an occasional twitch at most.
Jigs can be big tail water medicine too. At most of the fly shops in Bozeman the cash register engineers will tell to take white jigs with you. My old and now departed fly tying buddy Willy Self had a white jig he liked to use at the tail-outs below long pools on the Big Horn. Olive and black Woolly Buggers are always a good choice early in the day, when fish don't yet seem to be foraging for insects yet.
My now departed fishing buddy of many years John Wilson had a white jig too that seemed to work everywhere, especially so on days when nothing else would. John like to tie his white jigs on hooks with a fat lead bead molded right onto the hook. Most of the pre-molded jigs you can buy were made with Croppies in mind, so they do tend to be made with thin light wire hooks. I like to use stout Gamakatsu jig hooks, and to mold my jig head with wire and super glue, or to lash a length of solid wire solder onto the bottom of the shank first.
Wet flies and nymphs are big part of the picture too. On tail water rivers nymphs are increasingly fished with a Bobber Hopper rig, or with a flat out bobber. But they don't have to be. I'll pick that thread up in a later section.
My home waters are the Gallatin Madison and Yellowstone. I'm a bit of an interloper when ever I do get to the slow smooth spring creek like tail waters in Montana. I have learned a little. Over the years. I like those rivers a lot.