We are currently entering early Summer here in Montana, due to a good snow pack and a cooler spring the rivers here in Southwest Montana are in different stages of runoff depending on the watershed. It is important this time of year to keep an eye on the water gauges as conditions will change daily. Many of our rivers are peaking right now while others are getting close to dropping into prime shape but are still on the high side. This is one of our absolute favorite times to target local waters as early summer hatches begin to unfold across Southwest Montana. River conditions change rapidly this time of year and one of our best recommendations is to learn to read the USGS hydrographs. While there is still a decent amount of snow in the high country rivers rise and fall based on weather conditions. Hot days will increase snow melt rates and result in rising flows while cooler weather will slow melt and result in dropping flows.
Warm weather is currently melting our snow pack and rivers are cold and flowing strong. In general, freestone fisheries that do not have dam controls can change rapidly from day to day. Freestone rivers and streams are those that rely heavily on overland flow from rain and snow melt. Freestone rivers that drain high elevation snow fields (like the Yellowstone River) are still on the high side, while others like the Jefferson are already in great shape. Spring creeks are fed by groundwater and are completely unaffected by run off and are peaking right now with PMD hatches. Some rivers are also fed from reservoirs that trap sediment. These tailwaters (Bighorn, Missouri, Madison etc) do increase in flows during spring runoff but they retain good water clarity and often great fishing. Stillwater reservoirs, ponds and lakes are also a very good option this time of year.
We are currently starting to see our summer hatches getting going. Stoneflies such as Salmonflys, Golden Stones, and Yellow Sally’s are becoming very active. The Salmonfly hatch has started on the Upper Madison, and is beginning to progress up stream. The Pale Morning Dun mayflies are showing up on spring creeks and several rivers. A variety of caddis species are also present on most rivers.
The safe bets right now are the waters that are protected by run off. These include tailwaters below reservoirs, spring creeks and still waters. The good news is that these three categories of fisheries are lights out right now and occur in abundance across Southwest Montana. Spring creeks have some lingering baetis hatches and the PMD’s, the best hatch of the year, are starting to get going. The fish are still fresh and haven’t seen a lot of artificials yet, so catch rates are often high. Tailwaters are also fishing well right now as water temps rise and the trout put on their feedbags. Dry fly fishing is variable and depends on flows and if they are bumping the dam releases or not. Nymph fishing is predictably good. If flows are on the rise fishing closer to the dam is often better because moss can often get dislodged and if you are too far downstream it can foul hooks. Stillwaters are also a great option and catch rates can be very high slow stripping streamers. Early Callibaetis mayflies can also produce good dry fly action on some waters.
Wild Card Options
While most of our freestone rivers are still experiencing runoff, each river system behaves differently and will exit runoff at a different pace. Generally speaking, the smaller the stream/drainage, the quicker runoff will subside. The Yellowstone River, which is a large river draining an immense area, is typically the last river in the state to clear up. However, some smaller tributaries like the Boulder or Stillwater will be fishable earlier than the main river. Knowing how to read hydro-graph data will help you determine when runoff is coming to an end. During runoff, the hydro-graph looks like a series of waves as the water rises and falls each day with snow melt. As the melt subsides, the graph will start to flatten out and decline steadily. You only need a foot or so of visibility to catch fish along the banks as the water is dropping, so don’t be afraid to target these kinds of conditions even though other anglers might consider the river to be unfishable.