PROJ00005

• Contract/PO #: C153402
• Contractor Name: Fort Lyon Canal Company
• Water District: 0
• County: Bent
• Bill Number: XB 99-999
• Loan Projects - Doc Type: Feasibility Study

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The emergency spillway would be located north of the outlet works (see Photograph
12) where a depression in the dam presently exists. As required by the State Engineer,
the spillway would have a capacity equal to the copacity of the inflow channel, and an
invert elevation of 3801, five feet below the dam crest. Based on the capacity of the
Fort Lyon Canal at the inlet structure, we estimate that the maximum inflow through
the inlet channel is 750 cfs. A 200-foot wide spillway will pass this flow rate with under
one foot of depth at a velocity less than five feet per second (fps). A wide spillway was
chosen to maintain a low velocity flow and thus permit a natural lining (e.g. grass) in the
spillway, rather than a more expensive artificial lining. The spillway will release flows
into the reservoir outlet channel and subsequently into the West May Valley Drainage
Ditch and the Amity Canal.

The reservoir outlet consists of a 200-foot long, three-foot diameter concrete
conduit, controlled by a single cast iron sluice gate located in the center of the dam.
The gate is presently inoperable and reportedly has been for some time; this is probably
due in port to a build-up of trash and sediment in the conduit upstream of the gate. Also,
there is a metal Parshall flume located in the outlet channel. The flume is in good
condition but overgrown with weeds and grass.

The work required to rehabilitate the outlet works is as follows:
I. Reconditioning the cast iron sluice gate;
2. Replacing the existing hoist with a threaded stem and hoist;
3. Installing a trash rock on the concrete pipe inlet;
4. Cleaning the Parshall flume.

The total estimated cost to rehabilitate Thurston Reservoir (including the inlet and
outlet works) is $50,900, as shown in Table B-8.

Control Basin. The control basin is located 8 miles north and 3 miles east of
Lamar, Colorado. It is supplied through a bifurcation on the Fort Lyon Canal located
approximately 102.5 miles downstream from the lower diversion dam. The control basin
is used to regulate the flow in the end of the Fort Lyon Canal. The water entering the
control basin is eventually released into the Wheatridge Lateral through an ungoged
channel at a uniform rate and head. The bifurcation is a concrete structure with an
adjustable steel check gate on the control basin inlet channel and a steel radial gate on
the canol (see Photograph 13).

Overall, the control basin and bifurcation structure are in good shape. The only
major problem is that of weed and trash control (see "Weed and Trash Contral,"

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