FLOOD08463

• County: Las Animas
• Community: Las Animas and Vicinity
• Stream Name: Arkansas River
• Basin: Arkansas
• Title: Arkansas River and Tributaries, Las Animas, Colorado, and Vicinity
• Date: 2/18/1964
• Prepared For: CWCB
• Prepared By: COE
• Floodplain - Doc Type: Project

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SUBJECT:

Arkansas River and Tributaries, Las Animas, Colorado,
and Vicinity

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5. Floods and da.ms.ges. --The flood threat to Las Animas and
vicinity is from the Arkansas River. The aggrading riverbed has
reduced channel capacity to the point that overbank flow occurs at
about 6,500 cubic feet per second and urban flooding occurs at
10,000 cubic feet per second. The maximum known flood occurred in
June 1921, with a peak flow of 187,000 cubic feet per second. A
recurrence of this flood under present conditions would cause
damages estimated at $3,135,000. With the authorized Pueblo Dam
in operation, the peak discharge would be reduced to 108,000 cubic
feet per second and the damages would then amount to $2,490,000.
Average annual flood damages with the authorized Pueblo Dam
operating are estimated at. $82,300.

6. other needs.--Irrigation reservoirs on minor tributaries
in the vicinity of Las Animas offer some recreational opportunities;
however, the fishery resources of the Arkansas River are extremely
limited because of irrigation diversions and the saline return flow,
and fishing in the vicinity of Las Animas is inadequate to meet
local demand. The municipal water supply at Las Animas, while of
adequate quantity, is of poor quality and the city is scheduled to
receive good quality water from the Fryingpan-Arkansas Project to
supplement its existing supply.

7. Improvement desired.--Local interests desire improvement
of the Arkansas River in the vicinity of. Las Animas to eliminate the
flood hazard. They state that heavy plant growth, aggradation, and
bank erosion threaten to change the river's course during floods
and make it flow tnrough the city. They state that they are planning
to build a public park adjacent to the city and that a small fishing
lake would be an important nucleus in the development of the park.

8. Plan of improvement.--The District Engineer finds that levee
improvements along the Arkansas River at Las Animas to provide for a
flo;; of 140,000 cubic feet per second would be t4e most feasible means
of providing flood protection at Las Animas and vicinity and that such
improvements would be compatible with an overall basin plan for water
resources development in the Arkansas River basin. The project design
flood of 140,000 cubic feet per second is 77 percent of the standard
project flood and has a probable frequency of occurrence of once in
about 360 years with the authorized Pueblo Dam in operation, as
assumed in this study. Without Pueblo Dam in operation, the frequency
is once in about 190 years, The District Engineer's proposed plan
would consist of 9.6 miles of levee on the right bank of the Arkansas
River and one. mile of levee on the left bank. Appurtenant works
include levee protective measures; an interior drainage system

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