FLOOD11630 ‎(2)‎

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

future directions for flood control system improvements.
Fonntain Creek and Tributaries
Flows from Fountain Creek and its tributaries run directly into the Arkansas River below Pueblo.
Increases in base flow from water transported across the Continental Divide to C;olorado Springs
that are dischazged into Fountain Creek following use and treatment by the city ~ias occurred
since 1952 with the construction of the Hoosier Tunnel Project. Tlus was followed by the
construction of the Homestake VJater Development Program in conj~nction wi~i the City of
Aurora in 1965. Finally, the Bureau of Reclamation completed construction of the Fryingpan-
Arkansas Project in June 1981.
The water rights to the share of water received by Colorado Springs through these projects are
fully controlled by the city. These rights continue for any discharge of this, so-c~iled, "trans-
mountain water" into Fountain Creek. The city is credited for the dischazge of trans-mountain
water into Fountain Creek (and therefore the Arkansas River) through stora.ge of Arkansas River
water at Pueblo Dam. This water is stored under a so-called "if and when" aman~ement. Under
this arrangement, if storage volume is needed for flood control or when downstream irrigation
districts place a demand on the storage volume, the water credited to Colorado Springs is
released. At that point, Colorado Springs rights to those waters aze lost. The city also loses
rights to waters lost through evaporation, ground percolation and bank losses during transit down
Fountain Creek. Colorado Spri.ngs is able to make use of water stored at Pueblo Dam by
pumping water back up through the Otero pipeline.
The increased base flow down the Fountain Creek and Arkansas River by discharges of trans-
mountain water does artificially affect the channel capacity to some degree. Mor~ importantly it
may have created a significant imbalance within the creek and river system that fi~rced changes
in the system in an attempt to achieve a new equilibrium. This adjustment process may be taking
the form of more meandering, increased bank erosion and channel bed degradation in some,
reaches and increased aggradation of the channel bed in other reaches. This on-going natural
process has negatively impacted upon properties along Fountain Creek in incorporated and
unincorporated areas like Colorado Springs, Manitou Springs, Security, Fountain;, Pinon, Pueblo
and others. As indicated earlier in this report (see Table 3-3), this process may also Y~e
contributing to the accelerated aggradation within the Arkansas River since 1965.
Development on Fountain Creek in the City of Manitou Springs has severely encroached upon
the floodplain. In the downtown azea, Fountain Creek is reduced to a narrow channel with a
conveyance capacity of around 1,000 c.f.s. This equates to approximately the 10-yeaz frequency
flood. A reconnaissance report by the Corps of Engineers in May 1995 (revised ~ugust 1996)
indicated that flood-warning systems providing 15 minutes to 3 hours advance notice of floodin~
on Fountain Creek do not allow su~cient time for emergency evacuation procedures. The
economy of Manitou Springs is highly dependent upon tourism. The tourist seasan coincides
with the summer flood season and creating a severe flood management problem. 'The speed at
which flows could overflow the nanow channel and create fast moving floodwate.rs several feet
Chapter 3- Flood of April ~?9, 1999
Post Flood Assessment Report ~ 28 Draji Revised o9/09/99