FLOOD11630 ‎(2)‎

• County: Statewide
• Basin: Arkansas
• Title: Post Flood Assessment Report - Arkansas River
• Date: 9/15/1999
• Floodplain - Doc Type: Flood Documentation Report

almost useless. Compounding the problem is the fact that Manitou Springs is a tourist
destination where a high percentage of the population during the peak storm season would be
visitors who are unfamiliar with flood emergency wamings and procedures. A 100-yeaz flow of
9,300 c.f.s. would cause over $46 Million in damages (April 1995 price levels). Of this amount
Manitou Springs would incur $29 Million in ciamages and Colorado Springs would incur $17
Million in damages. The flood depth created by such a flood at the Manitou Springs Hotel, a
three story historic structure, would be 17-feet. Despite the large economic impact and hazards
from flooding, a Reconnaissance Study for Manitou Springs in May 1995 (revised August 1996)
by the Corps of Engineers found no economically feasible solution to the flood problem.
Pueblo: In general, existing flood management systems prevent flooding from lazge storms
along the mainstem of the Arkansas River and Fountain Creek. However, Pueblo is still subject
to flood related problems fram Fountain Creek. The Fountain Creek bed has been aggrading
over the yeazs and has resulted in meandering and bank erosion problems here and in many
upstream locations. Recreational areas built within the $loodplain aze increasingly subject to
flooding and siltation. The problem is more indicative of a systemic problem involving the
entire watershed and nothing specific to flood management within the City of Pueblo. A
comprehensive solution will need to be developed to address this issue.
Arkansas River
Rocky Ford: The lack of by-pass features for the irrigation canals allows irrigation flows to
combine with local drainage flows from various arroyos intercepted by the canal. Despite the
high overbank location of Rocky Ford, the diversion of irrigation water towazds the city prvvides
a route for the Arkansas River to cause flooding. The combined volume of irrigation flows and
local drainage flows overwhelm the canal capacity and floods the city. Rocky Ford will probably
be affected more and more by lower frequency events as a result of channel aggradation. The
flood of Apri129, 1999 was not a very rare event and yet produced a recozd river stage in the
town of Avondale about 30 miles upstream.
La Junta: In the vicinity of La Junta, local officials report that channel agaradation has been as
high as 16 feet over the last 30 years. The subsequent loss of channel capacity creates a major
deficiency in the local flood management system. The Corps of Engineers cleazed the channel in
1956 under a small snagging and clearing project under Section 208 of the Continuing
Authorities program. Periodic dredging of the channel ta maintain the capacity has been lacking.
The increasingly higher riverbed is affecting local stormwater drainage and greatly diminishes
the flood control protection offered by local levees. The levee constructed on the north bank by
the Corps of Engineers was an incidental feature of the 1956 channel clearing project to provide
a low cost disposal site for dredged material. The levee has provided reliable flood protection
and has been well maintained, but on-going channel aggradation continues to diminish its
protective capability. The flood of Apri129, 1999 overtopped and eventually breached the levee.
Prior to this event, the levee provided protection from about an 8-yeaz flood. In its current
damaged condition, the levee only provides protection up to about the 5-year flood.
Chapter S - Flood RiskAssessment
Post Flood Assessment Report ~~ 38 Drafi Revised 09/09/99