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Floods (Continued from page 1) DTC had a maximum water depth of 8.2' and a peak outflow of 470 cfs. Almost immP1liately after the Denver storm had ended, and while Goldsmith Gulch flooding was at its worst, another storm developed in central Jefferson County over the headwaters of Lena Gulch. This second storm produced a 1.85" downpour near the intersection of US Highways 6 & 40 in Golden. At 4:35 p.m., the NWS issued a flash flood waruing for Lena Gulch, affecting Golden and Pleasant View where the MOllntAin<ide Mobile Estates entrance road was wn11(jated by 2 to 3-feet of water. Fortunately the storm was isolated and only resulted in minor flood damages and temporary inconveuience for motorists. Monday, July 28: As mentioned at the beginning of this article, July 28 will be marked in Colorado history as the day of the Fort Collins Flash Flood of 1997. The Denver area was under a simi1ar weather threat all day, bnt fortunately our nwnber did not come up, at least not in the disaster category. Some significant flooding did occur, however, with Goldsmith Gulch being hit hard for the second consecutive day, exceeding the prior day's peak at Eastman Avenue by one foot and setting a new record of 2040 cfs at 6:30 p.rn. Upstream at Temple Pond, Goldsmith floodwaters pooled to a depth of 9.5' releasing 500 cfs. Downstream of Eastman at Yale Ave. the peak flow was estimated at 1850 cfs and classified as a 10-year event. According to the Goldsmith Gulch design hydrology model~ the discharge at Eastman approached the 50-year mark. As with the previous day's storm, the lliff detention facility and improved channel reaches performed as designed preventing significant damages. By 9:00 p.m., Goldsmith Gulch floodwaters had combined with Cherry Creek flows causing the Marlret Street gage in lower downtown Denver to measure its new record peak of 3200 cfs. The Cherty Creek gage at Steele Street also set a new record at 2350 cfs. Heavy rains in other parts of Denver and Aurora caused localized flooding of many roads, parking lots and basements. In Aurora, road washouts occurred in the upper Sand Creek basin along Coal Creek at Gun club Road, Picadilly Road and Jewell Ave. Some homes in the Coal Creek floodplain also ~""t.inP1l damage. Unofficial rainfa11 estimates of up to 6" were reported in local Denver newspapers the next day. Table 1 shows the rain intensities and totals measured by the ALERT system for Goldsmith Gulch on July 28. In contrast, the disastrous Fort Collins storm occurred later in the eveuing and produced more than II" over a 4-hour period. Tuesday, July 29: Late eveuing rainfall on July 28 caused the Sand Creek ALERT gage to measure a new record flow of 4200 cfs at 2:47 a.m. (see July 19 discussion). At Sand Creek Pad< near its crossing with 1-225, the pedestrian trail crossing was overtopped by 4.4 feet, and the discharge was estimated at 3480 cfs, another ALERT gage record. While the search for victims was continuing in Fort Collins, readers of the July 29 Rocky Mountain News were greeted by a front page photograph of a 12-year- old girl and a car floating in a flooded parking lot at Quebec St. and Leetsdale Dr. in Denver. Wednesday, July 30: At 3:25 p. rn. a flash flood waruing was issued by the NWS for Boulder Creek and for sma11 streams in northern Jefferson County. Some landslides occurred in the mountains along South Boulder Creek and localized street flooding was widespread in the warning area. Fortunately, the heavy mountain rains did not cause any major stream flooding. Evening stortns in Aurora caused the Utah Pad< detention pond in the upper Westerly Creek basin to overflow onto adjacent streets, making headline news for local television stations. Precantionary sandbagging was performed by public works officials along Peoria Street between Mexico and Florida, safely conveying floodwaters back to Westerly Creek. Aurora officials estimate that flood levels at this location approached the l00-year threshold The ALERT system measured more than 3 inches of rain in the drainage basin above Utah Park. At 8:05 p. rn. the NWS issued a flash flood warning for Westerly Creek in coordination with officials from Aurora and the District. The Granby Ditch detention basin at East 6th Ave. ponded floodwaters 11 feet deep and came within 2 feet of overtopping the street This facility is designed to handle l00-year developed runoff. During the event, the ALERT gage at this location gave Aurora officials confidence that an emergency response at this location would not be needed. Thursday, July 31: Heavy rains in Arapahoe County and Littleton caused new ALERT gage depth records at Holly Dam (15 feet) on Little Dry Creek, and at the Grant Street detention basin (5.3 feet) on Slaughterhouse Gulch. Monday, August 4: Little Dry Creek in Adams County flooded causing damages to public facilities and homes in its lower reaches below Lowell Blvd. The fireplace store upstream of Lowell. frequently damaged in past floods, was spared this time by the 1986 construction of a new bridge. The bridge superstructure was partia11y inundated, but no road overtopping occurred here. Downstream at Grove Street, the KCNC-Channel 4 News helicopter rescued a man who drove his pickup into the floodwaters. Fire rescue crews were unable to safely reach the victim. Pedestrian bridges in this area were shifted along their foundation by as much as 3 feet by the force of the water and debris. .~ Table 1 - July 28 Peak Rainfall for Goldsmith Gulch (inches\ ALERT Station 10-min 30-min 6O-min Total Temple Pond at DTC 0.74 1.42 1.54 1.61 Goldsmith at F<ldm.n 0.67 1.34 1.46 1.85 18