ALP 3

Contents
Executive Summary
Researchers examined survival of nonnative fish species and embryos, post -larvae and fingerling
age classes through an energy dissipating sleeve valve at increments of atmospheric pressure
associated with the preliminary filling of Lake Nighthorse, Durango, Colorado from 2009 to
2011. The Objective of the study was to determine at what atmospheric pressure and discharge
pressure could a Pratt energy dissipating sleeve valve model 71,1( Henry Pratt Company)
effectively eliminate nonnative fish and embryo survival frdiWdisscharge water. The Sleeve
valve model 711 is installed inside the discharge pipe of Midges Basin dam near the terminal end
and has 0.63 inch holes in a helical pattern.
Pumping operations from the Animas River were tnifiated to fill Lake'14- ighthorse in 2009 and
full pool was achieved by July 2011. During tl'ti time the reservoir progressed from an elevation
of 6,730 to 6,882 with increasing atmospheric pressures rangingfirom 1.45 to"? "l.respectively.
Survivorship trials were held at elevations of 6,775 aricl 6,795A in 2009; 6,805, &;132.8 and 6,846
ft. in 2010; and 6,855 and 6,877 feel trr20 "11.
Small, 0 -plus and larger ( <75 mm), 1-ohts M40 suckers (75. 125mm) were utilized during
preliminary June and August 2009 testing ' but wera,trnavailable ftat.,#uture testing. Fathead
minnow post -larval to X11 1size fish (<75 "train), 10-plui.bl Ogill ( <*trim), and 0 -plus and 1 -plus
largemouth bass (<75ii m) wer ;used as test - species i'ring"2€;1Q,�2011. Rainbow trout embryos
(eyed stage) were used as surrogates for all rese it fish embryos due to their year -round
commercial availability:,"",. ,
Sixty two trials ,2009 ff1'1 consists "+ testing"2,354 white suckers, 1,800 bluegill, 2,793
lug e uth bass, 9,796 fathead "rrlitiow, and 33; 9,i rainbow trout eggs all subjected to
inc4h#tig water pressures through the sleeve valve. These nonnative fish and embryos were
inserted" upstream of the sleeve; valve acid flushed through at the 10 percent open position as the
reservoir filled -and pressureittteased froiri 27 — 71 pounds per square inch (psi). Rainbow trout
eggs proved to be"e most robitt,species and life stage tested. Rainbow trout eggs showed 12
percent survival atthumaximui� pressure tested (71 psi; 7.0 atm at 6877 ft elevation). Fathead
minnow and bluegill'wim", fttund`to have absolute zero survival 4 or less days after sleeve valve
passage at a reservoir elevation of 6,855 ft (62 psi). Absolute zero survival for largemouth bass
occurred at a reservoir elevation of 6,828 ft (50 psi). White suckers < 75 mm had survival of 0.7
percent while white suckers ranging in size from 75 —125 mm had 100 percent mortality at
reservoir elevation 6,795 ft. (36 psi) during preliminary trials. f This data suggest that nonnative
fish survival into discharge water can be completely eliminated at a discharge pressure of 6 s
g 1� y g 1t P
i
CommenE serwi (i ievm .97 r/as n z7 feet
t�etew full reservoir t86;6A9.9T+U�, Ih this rams,
(6,855 ft) and statistically significantly reduced at 50 psi (6,828 ft) for the fish species tested.
:'
the repo istates '
ranee Belo '.
However, nonnative, rainbow trout embryo survival could not be eliminated at any of fire
%
do 682818 M
resomirr((567910 g/r1 � is 54 feet below 09
we will be cipereting in
reservoir elevations and pressures tested. I
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