HYDRO21865

• Permit No: M1985026
• IBM Index Class Name: Hydrology
• Doc Date: 10/28/1985
• Doc Name: CHALLENGER PIT - FN M-85-026
• From: TUTTLE APPLEGATE RINDAHL INC
• To: MLRD
• Media Type: D
• Archive: No

The atreamflow entering the lake will not thoroughly
stored water. Because of the relatively short die
the inlet and the outlet, the river will probably
through the lake. Thies will reduce the deten
atreamflow entering the lake and thus reduce t.
suspended sediment carried into the lake that ca.
The trap efficiency of this small lake is not going
sediment, other then the heavier particles, to
lake. Consequently, the discharge of water from
the lake will not be completely free of sediment
released from large dame.
The creation of this lake will not change the
existing river channel. This is a major fa
degradation downstream of large drama, but will
this project.
Finally, if some degradation does occur, the gra
stream channel material can play a major role. Equ
be quickly reached if a well graded alluvium
gradation analysis shown in the Appendix is for
lines the stream channel. As can be seen, there is
of coerce materials which can form an armor coot. S
armoring effect have shown that Sx of the coerce
form this armor coat. Calculetiona performed on
stream, based on U.S.G.S. stream flow data, ind
maximum of 0.02 feet of degradation could occur i
was discharged from the lake outlet. Thies indicat
of expected degradation will be negligible.
Conclusions and Recommendations
The following conclusions and recommendations ere
this study:
1. The creation o£ a lake of the proposed ai
Thompson River at the proposed location is expected
appreciable effect on the downstream conditions
channel. The amount of sediment that will be tr
lake will be small except during flood periods.
proposed construction of a dam or changing of the
river channel. The trap efficiency of a reservoir
will be limited only to the larger particles. Th
the sediment will remain in suspension and pass thrq
nix with the
sate between
port circuit
Lon time for
amount of
settle out.
~ allow much
sttle in the
ie outlet of
such ea that
lope of the
r in causing
enter into
ation of the
librium will
exists. The
seterial that
an abundance
:udiea o£ the
material can
:hie reach of
.cated that a
clear water
sa the amount
offered from
ce on the Big
:o hove no
~f the river
speed by this
There is no
slope of the
~f this size
s majority of
sqh the lake.
2. There will be no change to the existing dlacha ge pattern of
the river. It should be pointed out that the olorado - Big
Thompson Project probably had n much more aignific rat impact on
this reach of river than the Challenger Project co ld ever have.
Large fluctuations in discharge which are characte istic o£ dame
will not be present in this project