Life on the Lower Fork

Although it bears only one name, the Henry’s Fork could be several different rivers over the first fifty miles of its length. This applies especially to the distinctive fisheries that exist above and below the majestic Mesa Falls.

Whereas the iconic section upstream exists nearly exclusively as a rainbow fishery, the stretch known as the lower river hosts what is basically an equal mix of rainbow and brown trout. Size is another separating factor in a stream that progressively gains influence from significant tributaries as it courses downstream toward the town of St. Anthony.
As home base for half of the year, a larger Henry’s Fork absorbs the majority of my attention through the months of November through April. Although the upper river becomes a serious distraction when I return to Island Park in early May, I will be as interested in the fishing on the lower river as any other portion until early July. This is the period when fishing between Ashton Dam and Fun Farm Bridge is at its productive best.
Beginning with Baetis in late March, a continuous series of insect events keep the trout looking up through three months that will only be interrupted by spring runoff brought on by melting snow. In most years, the disruption is tempered by the emergence of giant Salmon Flies that are not hampered by higher water and reduced clarity. Generally, flows will subside within a week or so of peak level, but twenty nineteen could be an exception.
With the majority of an above average snowpack remaining and reservoirs at or just below capacity, it is quite likely that higher water will be a factor for a longer period than is usually experienced. Additionally, it would be wise to be prepared for severe flows that could bring flooding to low land areas. However, this would be conditional upon a sustained stretch of extreme heat that may not occur in the near term. The hope for gradual warming is not unreasonable in a year marked by cooler than average temperatures.
Frankly, the threat of unusually high water is the only perceived negative to appear in an otherwise positive outlook for the lower Henry’s Fork.
Spawning activity is a reliable indicator of current and future trout populations, and with this in mind, the outlook is quite good.
In the fall, it was encouraging to see expanding areas of brown trout spawning habitat, which implies an increasing number of that noble species. A noticeable growth in spring spawning activity indicates the continued rebound of the rainbow population as does the impressive number of young healthy trout in the ten to fourteen-inch range.
Through nature’s kindness, two consecutive years of abundant winter flows appear to be contributing strongly to the recovery of a decline in the Henry’s Fork fishery attributed to the preceding years of instability with regard to the requirements of survival. With another season at hand, there could be no better news.


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