<br />'38
<br />
<br />FLOODS IN COLORADO
<br />
<br />MAJOR FLOODS-SOUTH PLATTE RIVER
<br />
<br />39
<br />
<br />atatlon
<br />
<br />Draingge area
<br />(square
<br />miles)
<br />
<br />Period of record
<br />
<br />he remembered distinctly that the peak of that flood just reached the
<br />top of the rail of the railroad track, wbich passes close to the gage.
<br />This has an altitude of 8.13 feet on the gage datum. A rough slope-
<br />arCl1 determination of the peak discharge was made, using the present
<br />slope of the water surface for medium stftge, and a cross section 8 feet
<br />narrower than the present cross section, because the resident stated
<br />that the channel was widened by that amount during the flood of
<br />1919. The peak discharge was thus estimated to be 9,800 second-feet.
<br />A series of cloudbursts during the last part of July and the first of
<br />August 1919 caused short, sharp floods on St. Vra.in Creek. The
<br />Lyons Recorder, August 2, 1919, describes these floods:
<br />
<br />The heaviest and most destructive cloudburst and downpour of water in the
<br />memory of the oldest inhabitant visited LyoDs on Wednesday [July 30] between
<br />2:30 and 3:45 p. m. It took out all the brirlges on the North St. Vrain for a.bout
<br />5 miles up and 5 miles downstream. The Longmont and Lyons water mains up
<br />the canyon were torn out in many places. Not only were the bridges washed
<br />. 'a~vaYI closing the road to Estes Park, but miles of road was torn OU~ along the
<br />narrow canyon.
<br />The people living on the lowlands along the banks of the river were flooded out,
<br />and many abandoned their homes for higher ground and safety. It was no un.
<br />common thing to see an automobile, bridge, barn, ch!ckcn house, and other small
<br />buildings going down the stream at a. high rate of speed. North-side citizens
<br />* * * gave all the assistance possible to the residents [in the lower part of
<br />town] whose homes * ... * were in s rosring sea of water 2 and 3 feet deep.
<br />
<br />On tl1e following day, ,July 31, another storm, not so severe but of
<br />longer duration, raised North St. Vrain Creek nearly as high as on
<br />the 30th and again flooded the houses in the lower part of town and
<br />washed out 300 yards of railroad track east of Lyons.
<br />During an investigation of this flood made in 1939 the Geologieal
<br />Survey learned from the same resident who furnished information
<br />relative to the 1894 flood, that the water surface in 1919 reached the
<br />base of the rail near the gaging station On July 30, and rose again Oil
<br />July 31 to noarly the same point. The stage of July 30 increased the
<br />ehmmc1 width by 8 feet. Using the present cross section and slope of
<br />water surface, the peak discharge which occurred about 4 p. m,
<br />July 30 was computed as 9,400 second-feet. The right bank was
<br />inunuated for a width of 300 feet. Thc mean daily discharge for the
<br />period ,July 30 to August 3, when the St. Vrain Creek gaging station
<br />was out of commission, was estimated as follows:
<br />
<br />Daily discharge of St. Vrain Creek, July.SD-Aug. 3, 1919
<br />&cand-fut
<br />July 30__ u __ _'_.._ u,____, u_______________ __ ,_, ____ 1,900
<br />31_ _ __ ____ ~_ __ _ __ __._____ ____ _______v___________ 1,200
<br />Aug. L _ ,____"'u___ __,_ 'u,__,____,___ ,_________u 950
<br />2" _" _, ,_____ ___,_'u_ _,__,_____ _____ _________ 1,000
<br />3"_""_,____",_"",__",c,__,,,__,__,,,,___ 1,100
<br />
<br />September 9, 1933, was the highest recorded for the area since the
<br />flood of August 1, 1888.
<br />The general rains of September 2-3,1938, which reached cloudburst
<br />proportions On the divide between Cleo.r Creek and Bear Creek,
<br />centering around Genessee Mountoin, caused Clear Creek at the.
<br />gaging station III miles west of Golden to reach a peak discharge of
<br />4,090 second-feet at 9 p. m. September 2. The peak reached the
<br />gaging station 12 miles downstream, near the mouth, at 1 a. m.
<br />September 3, with a discharge of 3,650 second-feet. The flood was
<br />of such short <;Juration that the mean discharge for September 3 was
<br />only 840 second-feet.
<br />
<br />ST. VRAIN CREEK
<br />
<br />St. Vrain Creek is formed by the confluence of North and South
<br />St. Vrain Creeks, which drain the Front Range and emerge on the
<br />plains, uniting below Lyons. For a distance of 10 miles above the
<br />junction North St. Vrain Creek has a fall of 121 feet per milo, and
<br />South St. Vrain Creek 189 feet per mile. From Lyons to the mouth
<br />of the ereek, a distance of 31 miles, the main stream has a fall of 22
<br />feet per mile.
<br />
<br />Gaging stations on St. Vrain and NQrth St. Vrain Creeks
<br />
<br />North St. Vraln Creek at LoDlIDont Dam,
<br />near Lyons.
<br />St. Vrain Orook at Ly0D8d_.._____.__~_uu.
<br />St. Vrain Oreek at mouth, near Plattevilleu
<br />
<br />109 October 1925 to da.te.
<br />226 August 1887 to October 1892; June IBM to
<br />date.
<br />1,000 April to December 1915; February 1927 to
<br />date.
<br />
<br />The storm of June 1864 caused a flood the effects of which were felt
<br />severely in the St. V rain Vallev.
<br />The storm of May 1876 also caused a flood on St. Vmin Creek,
<br />but the only known reference to it is a stntement in the Golden
<br />Tribune, May 31, 1876, that at the junction of St. Vrain Creek and
<br />Lefthand Creek, at Burlington, the water sprend over the bottoms
<br />from bluff to bluff for 2 days.
<br />The general storm of May 31, 1894, caused a flood on St. Vrain
<br />Creek, of whieh the Boulder Camers., June 2, 1894, reported:
<br />
<br />All the lower part of Lyons was washed a.way, probably 20 houses being de~
<br />stroyed or ruined. Sheriff Dyer sa.id that, standing on the hills and looking out
<br />onto St. Vrain Valley, a lake 3 miles wide was in the picture.
<br />
<br />From information relative to the 1894 storm it appears that South
<br />St. Vrain Creek contributed the greater part of the flood. During
<br />an investigation made by the Geological Survey in 1939, a resident
<br />who had lived near the gaging station at Lyons during 1894 said that
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