High Water Success at Holter Dam

Holter Dam Hog 2

When runoff causes the rivers of southwestern Montana to swell, Toby Swank
heads to the tailwater of the Missouri River below Holter Dam.

photo by Toby Swank

Tis the season for high water here in southwest Montana now that our spring melt is finally under way. Unless you’re fishing stillwaters, tailwaters, or a spring creek, chances are that you’re going to be looking at some very dirty water. It looks like the high water will be here for a while, as most of the mountain ranges in the region are well above their long-term averages in both snowpack and moisture levels. That said, there is still some great fishing to be found; it just requires a little different thought process and some variations of standard techniques.

One of our favorite fisheries this time of year is on the upper Missouri below Holter Lake in the central part of Montana. This is a big, classic tailwater fishery that offers over 40 miles of Blue Ribbon wild-trout water. Long renowned for its “match the hatch” dry-fly fishing, this stretch of the river can offer some of the best nymph fishing an angler may ever see in May and June.

Rainbows are the predominant species in the river below Holter Dam, but brown trout are commonly caught, as well. The main part of the rainbow spawn is in March and April, during which time many of the resident trout leave the main river and head up the various small tributaries. Generally speaking, these fish return to the main river once the flows increase and the spawning season winds down in late April or early May. The trout are hungry this time of year, which, coupled with rising water temperatures and prolific insect activity, makes for some unbelievable fishing when it all comes together.

Holter Dam Hog

Knowing where to look and how to read high water are the keys to success
on a river the size of the Missouri in spring.

photo by Toby Swank

The crux this time of year is the high water flows that are controlled at the dam, which creates Holter Lake. Oftentimes these flows will be in the 10,000-15,000 c.f.s range, which makes wade fishing ineffective at best and dangerous at worst. So a boat and someone that knows how to read the high water make all the difference in the world. During high flows, the typical holding water areas characterized by changes in current found around drop-offs and structure become less available to feeding fish and, as a result, the trout tend to congregated wherever suitable water can be found. The ability to understand the difference in surface water speed and structure is the difference between catching fish and going home skunked.

The flies and rigs are typically the same, as we’d ever fish this time of year, with a variety of sowbugs, scuds, and small mayfly nymphs. Although a longer leader is sometimes necessary, sticking with a 9-foot leader and mixing up the amount of weight used is usually all you need to be successful in these conditions. Even though the volume and speed of the water is relatively high, the trout still look for slower water next to faster flows. The fact is that if the fish are sitting in 10-15 feet of water moving that fast, no amount of weight is going to get the flies down to them effectively, so we concentrate on finding fish in places that we can get to them with standard nymph rigs.

All of these factors come together along with little angling pressure to create one of the most rewarding times of year to fish in the region. With average trout sizes in the 16- to 18-inch range and population numbers around 3,000 trout per mile, it’s simply pretty hard to beat! So take a look at the calendar and consider a trip to the Missouri River near Craig this spring and you’ll quickly understand why we look forward to high water from time to time!

I recommend hiring a guide for at least a day or two unless you have a boat and are comfortable rowing in high water conditions. This stretch of the river is relatively placid but it only takes one miscue with dropping anchor in these conditions to ruin a trip. Always wear your wading belt if wearing waders, especially in these types of flows. Plan your floats accordingly keeping in mind that an 8-mile float that could normally be a long day can now be finished in just a couple of hours. Finally, plan on using heavier tippet to help with quickly landing these hard fighting wild trout.

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