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Later it was modified from its original design to facilitate the passage of river users- the ramp in the middle allows drift boats to pass, even at low flows as seen in the picture to the left.  Whether intentionally or not, this design resolves the principle safety issues we normally encounter with traditional lowhead dams, at all flows, even those beyond the range of where you'd see Drift boaters on the river.

Indeed, at higher flows, this diversion dam forms a water feature that is highly desirable in terms of recreation- the wave works at a wide range of flows and provides safe/easy passage for small craft such as kayaks at any flow.

At higher flows, the dam begins to form a wave that's very friendly in terms of recreation- it is a nearly ideal wave for recreational purposes- stable, smooth, great for surfing, and if you flip, you'll flush out immediately.

At medium-high flows, the shoulders of the dam begin to form as a partial-depth hydraulic, while the center ramp forms a longer, faster, flatter wave that remains green (that is, without breaking) in the middle.

At High flows, the gap in the middle closes, causing a breaking wave across the entire river that is less retentive than the shoulders are at medium-high flows.

At Very high flows, the shoulders wash out and the wave becomes enormous in the middle.

The result is a structure that not only serves its chartered purpose, (that of water diversion during medium and low-flow conditions to supply the fish hatchery) it also provides positive recreational utility at some flows, without creating safety hazards at any flows.  Truly, this is a model of responsible river use.