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<br />A l~ft-bank tributary at about 7,640 feet with an estimated <br />drainage area of about 0.4 square mile, does not have any alluvial fan <br />or other ~vidence of sediment transport. The channel is about 2 feet <br />wide and less than a foot deep. Rocks are completely covered with <br />grass, vegetation, moss, or lichen to within 0.5 feet of the <br />streambed. The recent discharge is about 20 cubic feet per second. <br />Note that maximum water level can be slightly higher than the moss and <br />lichen l~vel before abraiding them. There is no flood debris lodged <br />upstream from obstructions. This lack of flood evidence indicates <br />that flows have not exceeded the erosion threshold discharge of 200 to <br />300 cubic feet per second for 100 years or more. <br />Ruxton Creek, both upstream and downstream from this tributary, <br />has a width of 3 feet and grass, moss, and lichen grow to within 0.5 <br />foot of the streambed. There are no tree scars or flood debris, or <br />evidence of significant sediment movement. This would indicate that <br />recent through maximum flows in the last hundred or more years have <br />b~en no larger than about 300 cubic feet per second which is <br />consistent with maximum snowmelt runofI in Colorado. <br />At Artist Glen tributary at an elevation of 8,000 feet with an <br />estimated drainage area of 0.8 square miles, the channel was very <br />similar to the 7,640 foot tributary; the channel width is 2 feet. <br />Recent peak discharges have been about 20 cubic feet per second. This <br />lack of flood evidence indicates that flows have not exceeded the <br />erosion threshold discharge of 200 to 300 cubic feet per second for <br />100 years or more. The canyon walls are very steep and have minimal <br />vegetation on the slope, however there is no noticeable rill or gully <br />erosion. <br />Because of the location of the Pike's Peak cog railway which <br />follows the Ruxton Creek drainage to just above Ruxton Park at an <br />elevation of 9,200 feet, personnel from the railroad may be able to <br />provide some information on the amount and frequency of maintenance <br />associated with water runoff. Many tributaries flow under the <br />railroad and the station in Manitou Springs is located immediately <br />n~xt to the low water channel. The creek is channeled into a 5 foot <br />diameter culvert under the station. Any flows exceeding the capacity <br />of th~ culvert (probably less than 200 cubic feet per second) would <br />flow throught the maintenance buildings. If flows frequently exceed <br />about 200 cubic feet per second (the flood insurance report indicates <br />. <br />the 10 year flood is 2,540 cubic feet per second), the building and <br />buildings along Ruxton Avenue would be flooded almost yearly. Has <br />this been the case1 <br /> <br />Fountain Creek and tributaries upstream from Manitou Sprinqs <br />The drainage area of Fountain Creek upstream from Manitou Springs <br />is 71 square miles. Placement of State Highway 24 in the Fountain <br />Creek canyon upstream to Cascade disturbed, to an unknown amountl and <br />preclude paleohydrologic investigations, particularly of maximum <br />floods, Channel dimensions and deposits probably are representative <br />of recent channel forming flows. Therefore emphasis was placed on <br />tributary investigations. <br /> <br />~ <br />