Henry’s Fork, April 15th, 2023
Although snow currently dominates the banks of the river and limits access, here is a soon-to-be-performed action that will impact flow and therefore fishing from Island Park Dam downstream at least to Ashton Reservoir. Normal flow out of Island Park Dam is around 200 cfs this time of the year.
The Drought Management Planning Committee (DMPC) approved a spring freshet for April 25-27. Freshets are most effective at sediment scour and thereby aquatic insect habitat improvement when flows increase rapidly, to high outflows, and last for 48-72 hours. Flows are expected to be bumped to 2,000 cfs on the 25th and remain there until morning of the 27th. This was not easy to accomplish and has been most of a year in the making. For more information on this action, visit the Henry’s Fork Foundation web site.
FAQ: What is a Spring Freshet?
Updated: 2 hours ago
Freshet:
A high rate of streamflow for a short amount of time. Typically a natural process in rivers caused by heavy rain or rapid snowmelt.
The Two Freshet Types on the Henry’s Fork
On the Henry’s Fork, a freshet can be:
- Natural: from heavy rain or rapid snowmelt into a full or nearly full Island Park Reservoir, requiring a rapid increase in outflow from the dam
- Managed: a planned freshet, negotiated with water managers and decision makers, to achieve (or even improve on) the benefits a natural freshet brings
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