|
<br />long bridge spanning Fountain Creek was washed out in a flood in 1902 and was replaced by
<br />one 70 feet long, Succeeding floods have widened the channel even more, so that the bridge
<br />span now exceeds 200 feet, Due to the changing channel capacities, an estimate of the
<br />recurrence intervals of past floods would not be valid (Reference 11), Photographs of
<br />potential flooding at Manitou Springs are shown in Figures I and 2,
<br />
<br />Severe flooding in the Town of Palmer Lake occurs during the summer months as a result
<br />of convective-type cloudburst storms, Snowmelt flooding is minor compared to rainfall-
<br />produced floods, Steep slopes and soils with low permeability cause rapid storm runoff with
<br />minimal warning time for evacuation of the floodplain, The only documented flood damage
<br />occurred during the June 17, 1965, cloudburst-produced flood, Shallow depth flooding
<br />occurs in Butler Canyon due to overland flow on an alluvial fan,
<br />
<br />The water-surface elevations for the 100- and 5oo-year floods at selected locations in the
<br />study area of Palmer Lake are shown in Figures 3 through 6, The flood elevation for the
<br />June 17, 1%5, flood is also shown in Figure 2, but was not available for the other locations,
<br />
<br />2.4 Flood Protection Measures
<br />
<br />Two significant water-regulating facilities in the area are Kettle Creek Diversion Dam and
<br />Big Johnson Reservoir. The latter is also called Fountain Valley Reservoir Dam No, 2 and
<br />is located east of the Security-Widefield community, Big Johnson Reservoir is privately
<br />owned by the Fountain Mutual Irrigation Company for the primary purpose of irrigation, The
<br />drainage area is approximately 3,1 square miles and the maximum storage is 7,000 acre-feet.
<br />The dam was modeled as having no effect on the 100- and 5oo-year water-surface elevations,
<br />
<br />Kettle Creek Diversion Dam, owned by the U.S, Air Force, is located on U,S, Air Force
<br />Academy grounds, The earthen dam was constructed for flood control and the reservoir
<br />receives water from a drainage area of 16,3 square miles and has a maximum storage of
<br />2,900 acre-feet. The dam was designed to detain flows associated with the Standard Project
<br />Flood (SPF) for the Kettle Creek basin and limit the discharge to approximately the 10-year
<br />recurrence interval.
<br />
<br />The Peterson Field Drainage is controlled by stream-water detention ponds sited at the
<br />Peterson Airfield, These ponds substantially reduce the peak flows from the upper 3.5 square
<br />miles of drainageway,
<br />
<br />The Templeton Gap Floodway (Reference 14) consists of a 10,590-foot-long trapezoidal
<br />channel extending from Templeton Gap in a southwesterly direction to Mile 5 on Monument
<br />Creek, The floodway has a capacity of 14,000 cfs (approximately a 1oo-year frequency
<br />flood),
<br />
<br />There are several small earthen dams, stock ponds, canals, and diversion ditches in the study
<br />area, but they have no regulatory significance, Generally, the structures divert low flows for
<br />irrigation and have little or no effect on major flows,
<br />
<br />Portions of several streams in the Colorado Springs area have been channelized in concrete
<br />drainageways with sufficient capacity to contain loo-year peak discharges, Streams where
<br />this has occurred are Bear Creek, Camp Creek. Douglas Creek (North and South), Sand
<br />Creek, Spring Creek, Peterson Field Drainage, Rockrimmon Basin. and South Shooks Run,
<br />
<br />14
<br />
|