July Fishing on the Montana Spring Creeks

July weather, stream flows, and summary

July on the spring creeks of Montana’s Paradise Valley—Nelson’s, DePuy’s, and Armstrong’s—begins with some of the world’s most prolific hatches of Pale Morning Dun (PMDs) mayflies ever seen on a small stream. These creeks flow through private property and require a rod fee to legally gain access and fish. Available dates to fish any of the three creeks in early July are very hard to obtain. This is a testament to the quality of hatches, trout, and fishing opportunities occurring on the spring creeks in July. 

Because the hydrologic sources for the spring creeks are naturally occurring springs—they bubble up from the ground at a constant 52 degrees F—summer-time fly fishing on Nelson’s, DePuy’s, and Armstrong’s rarely changes from year to year. 

Angling days in July are long, averaging just over 15 hours of daylight a day. The average daily high temperature of 80 degrees F reflects the long days of sunshine. Only 1.2” of accumulated precipitation falls in July, making it one of the driest months of the year. With these long, warm days it is important to know what to expect throughout each angling day. 

The spring creeks in July feature many things that make summer-time fly fishing in Montana so desirable. With abundant hatches, pleasant weather, and the backdrop of the Absaroka and Gallatin Mountain Ranges of Paradise Valley, and it easy to comprehend why the spring creeks are featured on magazine covers on a regular basis. 

July fishing: what to expect

The fly fishing on Nelson’s, DePuy’s, and Armstrong’s spring creeks in early July is identical to late-June, with the exception a few sulfur mayflies added to the throngs of Pale Morning Dun (PMDs) mayflies already floating on the surface. 

Prior to hatches of PMDs and sulfurs, anglers should look subsurface for actively feeding fish. With clear water and plenty of trout habitat, many nooks and crannies can hold subsurface feeding fish. A good pair of polarized sunglasses and a ball cap to shade your eyes are essential. Walk slowly and target any change in depth created by any small depression, weed hump, bucket, pothole, or the subtle drop-off below a riffle. Shallow water, two fly nymph rigs fished with a light yarn or pinch-on indicator are ideal. Choose PMD or sulfur nymphs or emergers in size 18 to 20 and fish nothing shorter than a 12- or 15-foot leader tapered to 6X fluorocarbon. 

As the hatches increase in frequency—in other words more and more adults are seen floating on the surface—rising trout may follow suit quickly. Once plenty of rising trout are seen, the fishing during a PMD or sulfur hatch on the spring creeks actually gets easier…because you can see a specific trout and spend time targeting that specific fish. As long as the fish is not “lined”—an errant cast that sees the fly line landing directly over the fish—most spring creek trout continue feeding even after multiple drifts are made. Which is good, because it might take one drift or it might take a hundred to get the perfect drift that convinces a trout to eat your fly. 

If hatches of PMDs and sulfurs are small, trout may still actively eat midges. This is a subsurface game requiring lightly weighted tandem nymph rigs. Most leaders are 12-feet long, tapered to 5X or 6X fluorocarbon tippets with midge patterns in sizes 18 or 20. 

Terrestrials are also good options for fishing the spring creeks in July. Nelson’s, DePuy’s, and Armstrong’s all have abundant habitat for streamside terrestrials, so if a hatch is small or it is too windy for hatching mayflies to stay on the water’s surface, prospecting with terrestrials is always a good idea. 

Wind can play a factor in a day’s fishing on the spring creeks. If winds in excess of 15 MPHs are forecast, many of the hatching dry flies are unable to stay on the water as they get blown off before a trout can consume them. Plus, long leaders that are essential for success are a little more difficult to cast. On windy days, knowledge of the creeks is essential, as plenty of sections exist that may be tucked away or out of the prevailing wind. 

Favorite patterns for fishing PMD and sulfurs hatches on the Paradise Valley Spring Creeks in July are: 

Sawyer Pheasant Tail Nymphs in sizes 18 to 20

Quill body sulfur in sizes 18 to 20

Biot emergers in size 18 to 20

Wondernymphs in sizes 18 to 20

RS2 emergers, preferably with CDC, in sizes 18 to 20

Hairwing duns in sizes 18 to 20

Pink Albert in sizes 18 to 20

Parachute duns in sizes 18 to 20

CDC duns in sizes 18 to 20

Where to find July trout on Nelson’s, DePuy’s, and Armstrong’s spring creeks

July fly fishing on the Paradise Valley Spring Creeks should be all about matching hatches of Pale Morning Duns (PMDs) and sulfur mayflies. Most of the time it is, but sometimes it isn’t. Because of the consistent stream flows and water temperatures, trout on the spring creeks in July are found in similar locations day in and day out, only moving small distances as different food becomes more available. 

PMDs begin hatching in late June and last until late July, with their strongest emergences in early July. Sulfurs begin hatching in early or mid-July and can last into early August. PMDs and sulfurs live in similar habitats in the spring creeks, so when a strong emergence of either species occurs, look for fish in slow current seams, on shallow flats, a slow seam next to a fast seam, any shallow water adjacent to any deep water, eddy lines, and seams behind rocks or seams created by faster water being slowed down by slow water.

PMDs hatch mid-day and sulfurs typically hatch in the late afternoon. Because the spring creeks are loaded with aquatic insects, trout will begin feeding on nymphs well before any adult mayflies are spotted on the surface. Before any adults are spotted, most fish will be found in slower, deeper water and then as a hatch begins the fish will adjust their locations based on the available insects.

If hatches of PMDs and sulfurs are small or it is still early in the day, look for fish to be eating midges. Many of these fish can be seen because the water of the spring creeks is very clear. If fish are spotted and they appear to be active—shifting from side to side and opening their mouth—then a well-presented shallow-water tandem nymph rig may entice feeding fish in these subtle drop-offs below a riffle.

When hatches dwindle or if prospecting is more exciting than sight-fishing, the spring creeks are flanked by fields of tall grasses. As the sun rises and the grasses warm and perhaps a breeze begins, casting a terrestrial into holding and feeding lies can entice a strike. Trout on the spring creeks tend to be more selective and eat on hatching insects rather than opportunistically feeding on whatever passes by, but riffles, shelfs below riffles, seams along banks, or shaded cut-banks are all possible locations where a well-presented grasshopper, ant, or beetle can produce a take. 

Important July hatches

The main hatches in July on the spring creeks are Pale Morning Duns (PMDs) mayflies, sulfur mayflies, some caddis, and some trico mayflies. PMDs and sulfur mayflies can be very thick at times. With the spring creeks overall abundance of runs, riffles, and shallow flats and a stream bead of cobble-sized rocks and weed beds, the river is home to ideal habitat for PMDs and sulfurs. 

Mostly emerging out of riffles and shallow flats, PMDs and sulfurs create ample opportunities for discerning anglers to enjoy matching-the-hatching situations to individual rising trout. 

Trico mayflies hatch in the early morning hours and can also provide opportunities for small fly dry fly fishing. Trout on the spring creeks may feed on trico nymphs but will often rise to adults floating on the surface or “spent” adults—insects that have mated and are now dead—and are floating lifeless on the surface. 

Caddis hatches can be sporadic throughout July, with the strongest emergences occurring in the few hours surrounding evening twilight. Most caddis on the spring creeks are tan or brown and in sizes 16 or 18. 

Terrestrials—insects that live the entirety of their life on land—can supplement a trout’s diet in late July. Grasshoppers, crickets, ants, beetles, spiders, and any other land-dwelling insect that may inadvertently find its way onto the surface may be targeted by trout as well. 

Midges are active year-round on the spring creeks and make-up a massive chunk of a trout’s diet. Fishing midge patterns is best done subsurface as part of a weighted two fly rig. During July trout eat midges, but mostly in the early morning hours, as if they were an appetizer for the forthcoming hatches of PMDs. 

Strictly subsurface, scuds and sowbugs are not exactly what an angler may think of when it comes to hatches. Often thought of as the same insects, a scud resembles a freshwater shrimp and a sowbug looks like a “rolli-polli” bug. Especially if hatches of PMDs, sulfurs, or midges are small, a trout on the spring creeks in July may eat a well-presented scud or sowbug.

Paradise Valley Spring Creeks fly box for July

PMD dry flies size 16 to 20

PMD emergers size 16 to 20

PMD nymphs size 16 to 20

Sulfur mayfly dry flies in size 18 to 22

Sulfur mayfly nymphs in size 18 to 22

Sulfur mayfly emergers in size 18 to 22

Trico nymphs in sizes 18 to 22

Trico duns/adults in sizes 18 to 22

Trico spinners in sizes 18 to 22

Caddis pupae size 18 to 22

Caddis CDC emergers size 18 to 22

Caddis dry flies with tan or black bodies in size 18 to 22; 

Grasshoppers, in tan, grey, or black, in sizes 8 to 16

Ants, crickets, and beetles in sizes 12 to 18

Scuds in sizes 16 through 20

Sowbugs in sizes 16 through 20

Midges, especially Zebra midges in black or red, in sizes 18 through 22

Streamers in olive, black or brown in sizes 2 to 6