| The Big Fish River is an open river. There are no dams to
slow or control the flow, and there are no diversions for agriculture. The
Big Fish delivers 4 million acre-feet (MAF)
in a year. The winter months tend to show average flows while the flows during the Spring runoff are much higher. Flows decline to a low in August and return to average values by November. The Big Fish River is famous for the salmon that return to their spawning grounds each year. The spawners deposit their eggs in the fall, and the fry emerge in the following spring. These young fish then compete with one another for food and space. Those that succeed survive and grow. After a year, they are ready to make the dangerous migration to the ocean. The juvenile migrant is called a "smolt." |
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| This smolt migration begins in April and continues into May.
The smolts migrate down the Big Fish and into the Idagon. It has been determined
that high flows in the Idagon immediately after its confluence with the
Big Fish are extremely important to aid the smolts in their journey to the
ocean. (Higher flow means faster flow; and faster water flow is thought
to speed the smolts down the river.) A speedy trip down the river is crucial
if the smolts are to reach the ocean in time to avoid high mortality from
the physiological changes to prepare for saline conditions (see chapter
13 of Modeling the Environment). For these reasons, a high April flow in this key reach of The Idagon is one of the goals for managing the river. |
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