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64 FLOODS IN COLORADO of precipitation was recorded, the rise in the creek due to it had passed before the main flood reached Denver. From statements of residents throughout the basin it appears that the heaviest precipitation occurred in the lower half of the basin, extending from Franktown to a point about 5 miles north of Denver, and that the rain was particu' larly heavy below Parkcr. In this section the rain was so intcrmingled with hail and came down so fast that it was said to be difficult to See a hundred yards. The precipitation above Franktown was slight and, according to J. Eo Field (see p. 62), did not extend to Castlewood Dam. The storm apparently traveled in a northwesterly direction and covered the entire basin, although with varying degrees of inten- sity, At Franktown the rain was heaviest about 2:30 p. m., continuing steadily for scveral hours. Betwecn Franktown and Parker the storm was at its maximum between 3 and 4 p. m., and below Parker the maximum occurred from 4 to 4:20 p. m. The rain caused every dry gulch to run bank full, and as the storm apparently traveled down- stream at about the same rate as the water in Cherry Creek, the cumulative effect was nearly the maximum for a storm of that inten- sity. The banks of Cherry Creek, being low, were flooded in numerous plnces. The Cherry Creek Flood Commission cstimatcd that the flood originated in the run-off from an area of less than 200 square miles, . and that the greater part came from an area not exceeding 100 square milos, Two points were selected by the Commission for slope-area measurements of the peak flow, based on the cross section to the high- j water mark and the slope of the creek bed, using 0.030 as the value for n in Kutter's formula. One was at the Montgomery Bridge above Parker, where the diseharge was found to be 14,500 second-feet. The other was below the mouth of Goldsmith Gulch, about a mile upstream from the city limits, where a diseharge of about 25,000 second-feet was indicated. In view of the results obtained in Denver, as described below, it is believed that tile figure for Goldsmith Gulch is too high, cven allowing for the flatteniug effect of storage between the two plaees, and for the longer peak in Dcnver, In Denver, Chcrry Creek started to rise shortly aftcr 8 p, m., and reached its maximum stage at 10 p. m., when it was 11 fcct deep at the Bannock Street Bridge. Soon afterward it began to fall and by mid- night had fallen 8 feet. At 8 o'clnek the next morning it had fallen another foot, to a depth of 2 feet in the channel, and eontinucd to recede slowly. The Flood Commission made no estimate of the peak flow in Den- ver, W. B. Freeman, consulting engineer, formerly a member of the Geological Survey, made a float determination of the velocity in the . main channel about midnight, when the stage was 5 feet lower than the , MAJOR FLOODS-SOUTH PLATTE RIVER 65 crest of the flood, and from this and the eross-13eetional area at the peak, ineluding the overflow, estimated the peak discharge as 11 ,000 second-feet. He further estimated the total discharge for the 12-hour period 8 p. m. July 14 to 8 a. m. July 15 as 4,000 acre-feet. C. W. Comstock," State engineer, in an account of this flood in Denver, states that the peak discharge at the gaging station on the South Platte River a short distance below the mouth of Cherry Creck was 12,000 seeond-fcet, of which he estimated that 10,000 second-feet came from Cherry Creek. His estimate of the total discharge was 3,800 acre-feet. 'fhe severe overflow was due to the fact that the channel had a capacity of only 6,000 second-feet. After the flood the capacity was increased to 10,000 second-feet. The flood of July 28, 1922, caused by heavy rainfall over the upper part of the basin, was a major flood for the upper part but not for the lower, as channel and vaHey storage so reduced its peak flow that it did not overflow the channel of the creek in Denver, although reaching the top of the retaining walls. It did, however, increase the flow of the South Platte River below the mouth of the ereek to such an extent that the South Platte River flooded several blocks at GlobeviJIe, in the lower part of Denver. A few days after the flood the Geological Survey and the State engineer's office made a joint investigation, the results of which have been published." The heavy rainfall covered an area extending 3 miles north of Parker, 1 mile south of Franktown, to the Douglas County line on the cast, and 4 miles .west of the creek. The heaviest rainfall was in the basin of Bayou Gulch, At a point 3 miles above the mouth of Bayou Gulch in scc. 30, T. 7 S., R. 65 W" the storm began about 2 p. m. and lasted for 2 hours. The total rainfall was about 3}j inches as measured in an iron wheelbarrow with nearly vertical sides, The precipitation was so intense that the water stood 2 feet deep in the road. The resulting flood at Bayou Gulch was the highest in nearly 50 ycars. At a point 1 mile above the mouth of the gulch the heavy rain lasted 45 minutes and the flood crest was reached about 3:45 p. m., remaining near that stage for one hour. Heavy rain at the mouth of the gulch is reported to have lasted one hour, Hallway betwcen Bayou Gulch and Parker, in sec, 3, T. 7 S., R. 66 W., the rain lasted from 2 to 4 p. m., and amounted to 2 inches as measured in a washtub in the yard. The rise in Cherry Creek came abont 3 p. m. A Weather Bureau station 4 miles east of Parker recorded 1.01 inches for the 24-hour period, but at Castle Rock 6 II Comstock, O. W" The Cherry Creek flood, Denv6J', Colo.: Eng. News, vol. 68, pp. 302-305, Aug. I&. 1912- II Follansbl'8. Robert, and Bodgu, ~. V., SOlDe fltods in the Rock)' MountaIn region: tJ. 8. 080]. Survey Water-Supply Paper 620, pp. 122-123,1925,