ALP 3

Contents
At the normal fill elevation of Lake Nighthorse at 6882 ft, the depth of the reservoir will be
about 150 ft from the water surface to the discharge outlet near the bottom center of the lake.
Therefore, embryo entrainment into discharge water is unlikely at the normal fill elevation.
However, embryos from bottom dwelling fish can become entrained into discharge water as well
as those of broadcast spawner's. But Broadcast spawner's such as the white sucker have a much
smaller chance of their eggs drifting into discharge water through underwater currents because
they typically spawn in shallow areas near the shoreline.
Sleeve Valve Passage Survival Testing at the 10 Percept Qpep Position
To test sleeve valve passage survival, we introduced "nonnative game fish, nonnative forage fish,
and nonnative fish embryos into the discharge pipe immediately upstream of the sleeve valve as
the reservoir filled. Each set of sleeve valve passage survival experiments occurred at or near
each additional increment of atmospheric pressure , The 10 percent open posit ion,of the sleeve
valve was selected as the minimum testing position based on the flow curve fro sleeve
valve manufacturer. The 10 percent open position is the'at conservative where water usage is
low and will allow for a greater probability of sleeve valve passage survival but will still have
the full pressure of the reservoir at its given elevatin. The elevation of the reservoir determines
the pressure of the water passing through the sleeve valve regardless of the open position of the
sleeve valve (figure 4). .
Sleeve valve passagi s, ival testing began sdoo,aiier the reservoir filled above its sill level
where water could be gravity fed,ipto the discharge >pipe. Initial testing using live specimens
during summer of 2009 wero intended tQ develop site- specific fish and fish embryo handling,
injectil i, and "refiie<vai methot)s and occurre when the reservoir was below its minimum pool
ele *00fi of 6801 ft. Atso to minimize water usage, the testing duration was held at 5 minutes of
elapsetfti e. Discharge through the pipe typically exceeded 20 cfs and velocities greater than 1
ft per second. The hydrostatie,,pressure passing through the sleeve valve will not change under a
consistent h4pstatic head lev therefore; sleeve valve passage survival experiments were
performed at dl**t reservoir Wevations to test the degree of mortality caused by sleeve valve
passage (i.e. greater ;pressure may result in increased mortality).
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