FLOOD08628

• County: Costilla
• Community: San Luis
• Stream Name: San Luis area drainageway
• Basin: Rio Grande
• Title: Master Drainage Study Town of San Luis
• Date: 12/1/1988
• Prepared For: San Luis
• Prepared By: WRC Engineering, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

Salazar No.1 has an appropriated storage volume of 99.75 acre feet, and
Salazar No.2, 35.0 acre feet. The reservoirs are located on the Dos
Hermanos Ranch and used for irrigating hay land.

Northeast of San Luis, the Rito Seco drainage is spread out into several
channels, natural and man made. Diversion dikes of natural soils,
however, force the runoff into the westernmost channel that runs from
north to south through the Town of San Luis. Since 1979, when the Army
Corps of Engineers constructed an emergency flood control levee around
the east edge of Town, and installed a 24" CMP at the channel location,
the flow in the channel through Town has been limited to that which will
pass the 24" CMP plus the runoff from the 4.5 square mile North Basin.
Although the channel has the capacity to carry the 100 year runoff from
the North Basin, flooding occurs because there is no defined swa1e or
channel to convey the runoff into the channel, and the sheet flow spreads
out to cover a broad area.

Th e grad i ent of the Ri to ,Seco between the two reservoi rs is approximately
1.6% and from Salazar No.1 to Cu1ebra Creek 1.0%~ The walls of the
channel between Highway 142 and the confluence with Cu1ebra Creek have
been 1 ined with stone to provide a more well defined channel. Computed
capacity of the channel is 300 cfs +.

Several channel crossing structures are located between Cu1ebra Creek and
the levee. Specifically a 36" CMP irrigation ditch crossing and two
minor wooden bridges between Cu1ebra Creek and Highway 142; five major
bridges and a twin 24" CMP installation between Highway 142 and the
1 evee. The twi n 24" CMP i nsta 11 at ion located at Hi ghway 159 is one of
the items that will be addressed in this report.

C. GROUND WATER CHARACTERISTICS

Throughout the San Lui s Valley, depth to ground water has hi stori ca lly
been very shallow. The ground water in the Town of San Luis is no
exception. Several free flowing artesian wells are located in the
southern part of town where the ground water level is very near the
surface. Recharging of the ground water by snow melt, stream flow and

-9-