Many back country roads are opening up meaning that some of our quality small waters are now approachable. However those that drain high country remain high and discolored. The Blackfoot River provides a good example of this situation. The river above the reservoir is running very high, but opens to fishing on July 1st. Roads leading to the river below the reservoir are open, but the river, now open to fishing, is running very high. The same applies to Fall and Teton rivers: approachable but running high and discolored. Expect the same for Palisades Reservoir tributaries, Salt River tributaries, Little Lost River drainage, Medicine Lodge Creek, and Robinson Creek. Warm River above Robinson Creek is running high and clear. Birch Creek is the exception. It is in good fishing shape. Being mostly of spring creek origin, it will remain so through the season.
Flow in the Blackfoot River above the reservoir is much higher (710 cfs at the Henry gage with 110 cfs being normal) than it has been for years. This is great news because silt accumulation compromises parts of this river. A flush from these flows can benefit both trout and aquatic insects. With more than normal snow pack remaining in the drainage, high flows could be around for a while making the outlook for cooler flows through the summer very good. What could really be beneficial here would be to have a number of consecutive years with flow this high in the river.
It’s a different year than the last few because of our winter with abundant snowfall in the high country. Not only is access difficult or impossible because of road conditions, and with warmer weather coming on, most streams are high and with discolor. For example, last year at this time the lower Blackfoot River was worth fishing with flow around 100 cfs at the Shelley gage. This year with roads mostly blocked and nearly 500 cfs at the same gage, it is time to go somewhere else.
Our 9-24-16 small streams fishing report offered some thoughts about the effects of significant rainfall on stream flow. We currently have a repeat of the weather conditions prevailing around 9-24. So again looking at USGS flow gauges on streams not influenced by an upstream reservoir reveals flow increases because of current storms. Current weather has been just what is needed to optimize seasonal aquatic insect activity for certain species, but it also adds food forms because of temporarily increased bank and bottom erosion. So it seems a good idea to once again include patterns imitating these food forms as well as streamer, caddisfly and mayfly life cycle, and terrestrial insect patterns in that fly box.
Flow out of Blackfoot River Reservoir has been reduced to 67 cfs. Not good for resident trout in the river below. Some good fishing on the Teton River in the Basin remains with BWO, mahogany dun and terrestrial insect activities bringing action on the river here. More good news here is that daytime recreational boaters are diminishing as cooler weather proceeds.
Observing USGS flow gauges reveals much information, even for streams not hosting such items. The big rain we had the last few days increased flows significantly according to readings on these gauges. So it is likely that a temporary flush happened on all these streams including those upstream of a reservoir (most of which are just beginning or soon to be impounding water). The increases are enough to bring about a temporary change in fly-fishing strategy by causing enough bank erosion that such as worms and immature burrowing insects are temporarily abundant food forms. So for the next few days, be sure to have such as San Juan worms, Suede Juan worms, and wooly buggers in that fly box.
Flow out of Blackfoot River Dam was reduced yesterday resulting a drop at the Shelley gage from 128 cfs to 87 cfs. This flow is not good for hosting fish and means they will face a tough time this winter. Let’s hope for their sake there are no further flow reductions.
Look for terrestrial insect patterns to be important flies for action on most any small stream until a killing frost comes along. Another consideration is that with shortening days and cooler weather, and absence of AM trico activity, afternoons will be the best time to find action. Also consider that with the uncertainties of a good snowfall this coming winter any tail water fishery (portions of Big Lost, Blackfoot, and Portneuf Rivers) will have low flows for the remainder of the season because of actions to fill depleted reservoirs.
We note that the flow out of Blackfoot River Reservoir was reduced significantly early today. Flow at the Shelley gauge is 128 cfs. Whether the flow stays at this level or not remains to be seen, but if it does, good fishing conditions are coming to the river about a month early. We will keep watch on how this develops. Meanwhile although the river above the reservoir is quite low, water temperatures are ideal. This makes for fish responding well to early AM trico activity and later in the day to terrestrial insect activity
Many of our small streams are impacted by the hot dry summer and therefore have lower than normal flows for this time of year. Given that condition, they heat up more quickly during daytime hours resulting in less dense aquatic insect hatches and lower fish activity. Thus the best time to fish these can be during morning hours when waters are coolest. Some of these streams feature morning trico spinner falls which adds to their early in the day attraction.