Flash Flood Alley Segements

Front Range Flood Histories (22 records currently -- expect 40 by April, 2005)

1 Denver
no images available



May 19 - 20, 1864
Heavy rainfall over foothills caused severe flash flooding with wave heights of 15-20 feet in a stream that is usually a trickle.
Deaths and Damage: 19 Deaths
Max. Precipitation: Unknown
Storm Center(s): Plum Creek watershed, just west of Denver
References: http://history.dpld.org/floods/1864.htm
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2 Boulder

Boulder Downtown

Boulder Downtown2

May 31-June 2, 1894
"(In the Left-hand Creek basin to the north of Four Mile Canyon Creek), the mountain towns, mining camps and upstream canyons of the area were perhaps the most severely affected by the 1894 flood. Most were virtually wiped off the map.....Left-hand Canyon areas sustained heavy damages. All bridges were washed out and roads obliterated. Sheriff Dyer stated that Left-hand Creek was over a half mile wide in places and that the farms along that creek were piled knee high with debris and sand....8.54 inches of rain from May 30 through June 1 was reported in Ward.
Deaths and Damage: ???
Max. Precipitation: 8.54 inches
Storm Center(s): Boulder County
References: http://bcn.boulder.co.us/basin/history/1894flood.html
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3 Boulder
no images available
August 19 , 1896

"The storm of yesterday tore up the road beyond Salina and made the passage of Four mile impassable. Considerable damage was done to property in Salina...... Boulder has not had such a dashing rain storm as that of yesterday afternoon for a long time. The lightening burned out the telephone of the Camera office. The rise of the creek in the south part of town was so rapid and of such threatening proportions as to cause great anxiety for two or three hours to the people living in that section."

Deaths and Damage: ???
Max. Precipitation: ???
Storm Center(s): Magnolia, Salina, Ward - Boulder County
References: http://bcn.boulder.co.us/basin/history/1896flood.html
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4 Denver (Morrison)
no images available
July 24, 1896

A large rainfall event - centered around Cub Creek near the town of Evergreen in Jefferson County - affected areas surrounding Morrison (Jefferson Co.).

Intense rainfall on 24 July 1896 centered on Cub Creek, a tributary of Bear Creek near Evergreen.

"Without a moment's warning the largest flood that ever came down Bear Creek struck Morrison about 8 o'clock (July 24), sweeping everything in its path ... although the water came down through the town nearly 3 feet deep in the main street, the buildings in the business section all withstood it." Twenty-seven lives were lost in the flood (available records do not indicate where the deaths occurred) and severe damages were reported from Evergreen to the mouth of Bear Creek. No rainfall records of this flood are available. The peak flow on Bear Creek at the Morrison gauging station was estimated at 8,600 cfs, which is the flood of record for the gage. The most recent hydrologic studies indicate that this flood would have a one in 40 chance of occurring in any year. It is not known to what extent Mount Vernon Creek contributed to the Morrison flooding."

Deaths and Damage: 27 Deaths
Max. Precipitation: ???
Storm Center(s): Evergreen, Jefferson County



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5 Boulder
no images available
July 8, 1906

Heavy rains over Sunshine Canyon on Saturday night and Sunday led to extensive flooding in the city of Boulder.

"A wall of water six feet high rolled up on Sunshine canon west of the Colorado Sanitarium Sunday afternoon and poured through Pearl Street. Augmented by the breaking of the Silver Lake Ditch, a torrent spread over a large territory and left its mark behind scattered all over the neighborhood. Railroad traffic was held up as the tracks were completely inundated. Great gorges were torn in the Sunshine road, which has been ruined for a mile west of town.

"The water spread at the point where the dry gulch comes into Pearl Street, rushed down through gardens at the corner of Third street, through Pearl and down into Walnut and Railroad street. Vast quantities of sand and debris were deposited on lawns and gardens. Water stood two feet deep on the platform at the Colorado and Southern passenger depot and the yards were so flooded that the tracks were invisible. The engineers could not see the rails, nor could the passengers alight of get on the trains.

Deaths and Damage: Damage to numerous downtown business and private property
Max. Precipitation: 2.8 inches (one of these inches fell in just 20 minutes)
Storm Center(s): Sunshine Canyon, just west of Boulder
References: http://bcn.boulder.co.us/basin/history/1906lood.html
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6 Boulder
no images available
July 23, 1909

Heavy rain causes flash flooding on two-mile and four-mile creeks west, northwest of Boulder.   Boulder creek was not highly effected.

The 'wall of water' caught a group of hikers and campers who descended Mount Sanitas to each lunch.   Of this party, two died from drowning and two others sustained severe injuries.   Others managed to climb to safety.

"The party took shelter under rocks when it began to rain at one o'clock, near the creek which was running full. Suddenly one of the party called 'look at the wall of water,' and all began to scramble for a higher place. Mrs. Ross, 76 years of age, was pulled out of the torrent by Mrs. Gumaer, and it was not until after her rescue that the party discovered that four were missing. All the party are suffering with hysterics and are unable to give a very accurate account of the affair."

Deaths and Damage: 2 deaths, 2 severe injuries; bridges and pipelines damaged
Max. Precipitation: ???
Storm Center(s): Two-mile and Four-mile Canyons, west of Boulder
References: http://bcn.boulder.co.us/basin/history/1909lood.html
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7 Boulder
no images available
July 30, 1916

Heavy rain centered over four-mile canyon caused a brief but strong flash flood.

"Floods from a cloudburst in Four Mile canon, sometimes called Two Mile Canon, swept down the creek at 8 o'clock yesterday morning, laving the farms north of Boulder, washing out Colorado and Southern tracks (located just east of the Diagonal) , east of Pleasant View school and damaging roads, bridges and irrigation ditches. The flood came and went in less than five minutes, but left several thousand dollars damage behind. No train reached Boulder from the north for 10 hours.

Though the 26th street bridge crossing (now Folsom Street) was covered with three feet of water it was not damaged by the flood. The flood water was from 10 to 12 feet deep on the Terry ranch. Green corn that stands 5 feet high was buried in water. Many thousands of dollars' damage was saved by the fact that the Beasley ditch (now Boulder and Whiterock ditch) that runs just east of the C. and S. tracks caught the flood water of Four Mile creek after it had washed away the railroad track. Persons who saw the deluge say that all the damage was done in less than 30 minutes. Like a monster wave, the flood burst out of the canon from the cloudburst one half mile up in the mountains and carried all before it."

Deaths and Damage: Several thousand (1916) dollars
Max. Precipitation: 1-3 inches
Storm Center(s): Four-mile canyon, west of Boulder
References: http://bcn.boulder.co.us/basin/history/1916flood.html
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8 Boulder
no images available
July 2-7, 1921
This storm produced general rains over the South Platte basin with the greatest amounts along the foothills. It covered an area of approximately 520 square miles and lasted 5 days. The maximum recorded rainfall was 5.29 inches and the greatest recorded rainfall intensity was 4.3 inches in 6 hours at Longmont. This flood was produced by a combination of rainfall and snowmelt. Although this storm caused overbank flooding neither discharges nor damages were recorded."
Deaths and Damage: Numerous structures destroyed, livestock injured and killed, transportation infrastructure (bridges, etc) badly damaged.
Max. Precipitation: 4.3 inches during six hours
Storm Center(s): Coal Creek and Four-mile Canyon
References: http://bcn.boulder.co.us/basin/history/1921flood.html
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9 Pueblo
Images to be posted
June 3, 1921

A great amount of rain fell just west of Pueblo on the afternoon of June 3.    Under intense pressure, the Shaeffer Dam broke and a great flood of water was released down the Arkansas river heading directly into downtown Pueblo.

On its way to Pueblo, the flood badly damaged the Rio Grande and Santa Fe railroad tracks.   When the waters hit town, hundreds of structures were literally ripped from their foundations, crashing into other structures or disintegrating in the muddy waters.

Over $19 million (1921 dollars) in damage was done to the city and over 100 people were known to be killed, with another 140+ people reported as missing.   The town of Pueblo was all but destroyed, yet residents did not give in.   Instead, an emergency meeting was held in Denver to discuss flood-control devices to guard the town against future floods.   New dams and a re-routing of the Arkansas river around town are a few of the changes made since this devastating and deadly flood.

Deaths and Damage: 120 deaths, $19 million in damages (1921 dollars)
Max. Precipitation: ???
Storm Center(s): Between Canyon City and Pueblo



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10 Boulder
no images available
July 31. 1929

"Rain fell throughout the night. The storm in Boulder broke at 5:30 and grew in intensity until 7 o'clock when it became a veritable cloudburst which continued until 9. The rain continued to fall practically all night. The heaviest rain fell in the front foothills.

Mr. Ford of the Denver-Boulder and Western railroad was told there was very little rain above the Gold Run mine in Four Mile canon. Bummer Gulch was the storm center. The wall of the new road up that gulch from Boulder canon was washed out. The article said 4.8 inches of rain fell. Three hundred feet of interurban track was washed out across South Boulder, two miles east of Boulder. A Colorado and Southern freight train's engine tender and seven coaches were wrecked near Marshall."

"Streets and Lawns Badly Damaged. City Engineer Salter placed an estimate of $4000 on the damage to roads, bridges and culverts in Boulder. Principal damage was on 10th St. from the Chatauqua to University avenue; 12th street from University avenue to Arapahoe. A large section of the Armstrong bridge in Gregory canon was washed out and 150 feet of Baseline in front of the Chatauqua golf course was covered with rock and gravel. Cement sidewalk across Gregory ditch on Marine was washed out. 'Reports of the flood attracted large crowds to all parts of the affected district' the Camera reported. 'The most interesting place from a spectacular standpoint was at 9th and Arapahoe. The water filled the cement ditch that runs through Highland school lawn and made an inspiring appearance as it sprayed up over the artistic bridge recently constructed for Riverside Drive. The bridge diverted the water across the new lawn, that has been the object of much admiration, onto 9th St., badly damaging the road."

Deaths and Damage: $4,000 in damage (1929 dollars)
Max. Precipitation: 4.8 inches
Storm Center(s): five miles west of Boulder


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11 Denver (west of town)
no images available
August 3, 1933

The 'unbreakable Castlewood Dam' breaks.

Torrential rains in the Cherry Creek watershed put tremendous pressure on the Castlewood Dam, which when built in 1890, was heralded to be able to withstand a catastrophic failure.

During the evening of August 3 rd , switchboard operators were notified that the Castlewood Dam was collapsing, and these operators began to warm people in the Cherry Creek valley.   This early action helped to save the lives of many people and livestock, but two deaths were attributed to the flood as well as $750,000-$1,000,000 in damage in 1933 dollars.

Onlookers reported seeing a wall of water 15-20 feet high rush down the canyon, destroying bridges and structures in it's way.   Another damn was built nearby in 1946, but remnants of the old damns still exist today as part of Castlewood State Park.
Deaths and Damage: 2 deaths
Max. Precipitation: 3-9 inches
Storm Center(s): East of Castle Rock




Horan, Patty. The Night the Dam Gave Way A Diary of Personal Accounts. (Franktown: Castlewood Canyon State Park, 1997.)

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12 Denver (west of town)
no images available
July 7, 1933
One of the most devastating floods in the Bear Creek Watershed...

Five persons known dead and great property damage of as nearly all of the highway between Mt. Morrison and Idledale is ruined.

A cloudburst at about 1 o'clock in the neighborhood of Idledale sent a wall of water down Saw Mill Gulch leading to Bear Creek, and another raging torrent down Vernon Creek.   The Vernon Creek waters reached a height of 15 feet in the narrow passage between the business houses.   The Highway up beautiful Bear Creek Canyon between Mt. Morrison and Idledale was practically ruined.

The peak discharge at Morrison was 8,000 cfs on Bear Creek and estimated as 1,500 cfs on Mount Vernon Creek.

Deaths and Damage: 5 deaths
Max. Precipitation: ???
Storm Center(s): Idledale, 20 miles west of Denver



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13 Denver (west of town)
no images available
August 9, 1934

The flood of 9 August 1934 in the Bear Creek basin was caused by heavy rainfall near Kittredge and at the head of Mount Vernon Creek. Six lives were lost and much property damage resulted. It was reported that Mount Vernon Creek ran higher than the previous year and much of the canyon roadway was destroyed. Damage to Morrison was reduced because the Bear Creek peak flow passed through the town before the Mount Vernon Creek high water arrived.

Mount Vernon creek shares its path with I-70 as the highway passes south of Golden and proceeds west into the foothills.

Deaths and Damage: 6 Deaths
Max. Precipitation: ???
Storm Center(s): Kittredge, west of Denver
References: http://alert.udfcd.org/bear_history.html
14 Colorado Springs
May 30, 1935
Intense rainfall over less than 100 square miles of the Monument Creek Basin led to a severe flash flood which swept through downtown Colorado Springs.   Measurements along Fountain Creek, formed in large part by Monument Creek just below downtown Colorado Springs, shows an instantaneous streamflow of 35,000 cubic feet per second (CFS) - a 50-year flood.   This flood claimed the lives of four people and washed out numbers bridges and roadways.   Be sure to look for dated pictures of this flood on the camera link to the right!
Deaths and Damage: 4 deaths
Max. Precipitation: 7 inches
Storm Center(s): Northwest of Colorado Springs



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15 Boulder
August 31 - September 3, 1938

"This storm produced general rains over all of eastern Colorado. The largest amounts of precipitation occurred in the mountains where over 6 inches was reported west of Eldorado Springs. Boulder reported 3.62 inches of precipitation from 31 August to 4 September with 2.32 inches falling during 2 September. Eldorado Springs had 4.42 inches of rainfall. Approximately 80% of the total precipitation falling in the South Boulder Creek basin fell in the late afternoon and evening of 2 September. The resulting flood, with a peak discharge of 7390 CFS arrived at Eldorado Springs at 10PM on 2 September. The peak gradually subsided as the flood moved downstream. A maximum discharge of 4410 cfs occurred near the mouth of Boulder Creek at noon on 3 September. Several buildings in Eldorado Springs were destroyed as a result of the flood eroding away their foundations. Numerous bridges were destroyed and the valley from Eldorado Springs to Boulder Creek and down Boulder Creek to the St. Vrain Creek was in shambles. This flood is the highest recorded flood on South Boulder Creek."  

Deaths and Damage: ???
Max. Precipitation: 6 inches
Storm Center(s): Southwest of Boulder



16 Denver (Morrison)
September 2-3, 1938

"An unofficial report stated that 7.9 inches fell just north of Morrison in six hours. The heaviest rainfall centered on the divide between Bear Creek and Mount Vernon Creek. The peak discharge on Bear Creek at Morrison above Mount Vernon Creek was 6,200 cfs. From post flood measurements the Mount Vernon Creek peak discharge was estimated at 9,230 cfs at a point 1/2 mile upstream from Morrison. From statements by local residents it appears that the peak discharge on Mount Vernon Creek reached Morrison at about 7 p.m., preceding that on Bear Creek by 1/2 hour. Six persons drowned when trapped in their automobile between Morrison and Kittredge. Damages in the basin were estimated at $450,000. If Morrison had not been warned, or if the flood had occurred late at night, the number of deaths would likely have been considerably higher. The photograph link to the right shows the relative level of this flood compared with the 100-year flood level. Note that this flood appears to have exceeded today's regulatory flood elevation by as much as four feet.

Deaths and Damage: 6 Deaths, $450,000 (1938 dollars)
Max. Precipitation: 7.9 inches
Storm Center(s): West of Morrison


17 Boulder
no images available
June 22, 1941

"Flash floods in Boulder County Saturday night and early Sunday swept a Longmont man from the arms of his wife and to his death, crumpled canon homes and carried others away intact, sent an automobile hurtling over a 150-foot embankment an instant after to car's only occupant had alighted, ravaged roads and bridges, and caused thousands of dollars of damage not yet officially estimated. The city of Boulder escaped almost entirely, except for minor flooding of a small area in the north part. Rain measured 1.04 inches [in Boulder]. Accompanied by a lightening storm of blinding intensity, downpours starting about 10:30p.m. Saturday sent already swollen streams raging over their banks and turned normally-dry gulches into furious torrents."  

The storm was centered over Sugarloaf Mountain just west of Boulder and primarily affected Four Mile and St. Vrain Canyons.   Numerous roads were partially or completely destroyed, most west and north of Boulder.

Deaths and Damage: 1 death, thousands of (1941) dollars of damage
Max. Precipitation: 1 inch in Boulder, more to the north and west
Storm Center(s): Northwest of Boulder


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18 South of Denver
web images
June 16-17, 1965

Perhaps the greatest flood in Douglas County history, the 1965 flood caused massive destruction to highways in the county, shutting down transportation south of Denver for weeks.

A tornado struck Palmer Lake on the Palmer Divide south of Castle Rock. The ground was already soaked from a day of rain the day before, and the torrential downpouradded several more inches of rain. East and West Plum Creeks, Cherry Creek and Kiowa Creek swelled with water.

By the time the flood reached Castle Rock on East Plum Creek, it was big enough to wipe out Highway 85 (Interstate 25) and all the bridges between south Castle Rock and north Denver.

Sedalia, at the confluence of East and West Plum Creeks, was completely inundated. The Presbyterian Church, Albert Manhart’s house, and a number of other buildings were completely washed away.

By the time the flood reached Louviers and Titan Road, a twenty foot wall of water was rushing down the creek bed. Denver began shutting down streets, rerouting traffic, and evacuating buildings as floodwaters from the South Platte and Cherry Creek crested through the city.

Throughout Douglas County, helicopters were used to ferry people and supplies across the flooded Plum Creeks, and people rode horses to get supplies across to Sedalia and points west. Eventually the waters receded into Kansas and Nebraska, flooding those states.

Deaths and Damage: 6 Deaths, $530 million (1998 dollars)
Max. Precipitation: ~14 inches
Storm Center(s): South, south west of Denver (near Larkspur)



19 Boulder
Video to be posted
May 7, 1969

"This was also a flood of long duration general storm. Precipitation was heaviest in the mountains; part of it being snow. In the Boulder and South Boulder Creek basins the rainfall continued at a moderate rate for nearly four days. Total precipitation for the storm amounted to 7.6 inches at Boulder and 9.34 inches at the Boulder Hydroelectric Plant located about 3 miles up the canyon from Boulder. Precipitation amounts totaled 8.11 inches at Eldorado Springs and 10.05 inches at Gross Reservoir on South Boulder Creek. Peak flooding occurred on the 7th of May at Boulder and Eldorado Springs. Preliminary estimates based on the gaging records, indicate a peak discharge of 1150 cfs occurred on Boulder Creek. Flooding extended over large portions of the flood plain starting at the junction of the two streams near Valmont Road and extending downstream through the remainder of the Boulder Creek study reach. There is also evidence of two bridge failures.

"The gaging records show that floods the size of the May 1969 flood occur on an average of about once every 5 years on Boulder Creek and about once every 7 years on South Boulder Creek.

Deaths and Damage: 1 death, thousands of (1941) dollars of damage
Max. Precipitation: 8-12 inches (11.27in. Morrison, 8.11in. Eldorado Springs)
Storm Center(s): Just west of Boulder, also extending north/south along the mountains



20 North of Boulder, South of Ft. Collins (Big Thompson Canyon)
Web Presentation
July 31, 1976

On July 31, 1976, the Big Thompson Canyon was filled with residents and visitors. It was the Saturday of the weekend commemorating Colorado's Centennial and the last holiday weekend before the start of school. That night a flash flood ravaged the canyon, causing the worst natural disaster, in terms of documented lives lost in Colorado state history. The death toll of the 1921 flood in Pueblo may have been larger. However, estimates of lives lost in that flood range from 100 to 350.

Heavy rain fell over a 70-square-mile area in the central portion of the Big Thompson watershed between 6:30 and 11:00pm. The most intense rainfall, between 12 and 14 inches, fell on slopes in the western end of the canyon. The flood washed out all stream and rain gages so accurate measurements were not possible. Yet, the impact of the flood could have been worse. The North Fork peak streamflow occurred approximately 40 minutes later than the Main Fork peak. If the two peaks had coincided, the peak streamflow would have been even greater than the 31,200 cubic feet per second recorded at the mouth of the canyon.

At least one hundred thirty-nine people died in the flood, and eighty-eight people were injured. Seven people were listed as missing. The flood destroyed 316 homes, 45 mobile homes and 52 businesses. Seventy-three mobile homes suffered major damage.

Deaths and Damage: 144 Deaths , $35.5 million (1976 dollars)
Max. Precipitation: 12-14 inches
Storm Center(s): Just east of Rocky Mountain National Park



21 Southwest of Denver (Buffalo Creek)
Video to be posted
July 12, 1996

On the night of July 12, 1996, a thunderstorm occurred in the area of the community of Buffalo Creek, Colorado. The storm produced heavy precipitation over a short period of time. A flash flood occurred along Buffalo Creek, Sand Draw, Spring Gulch, the North Fork of the South Platte River (North Fork) below its confluence with Buffalo Creek, and several other tributary streams in the area. Two lives were lost as a direct result of the flooding. Roads, bridges, water lines, and other utility lines were damaged or destroyed. Numerous homes, outbuildings, and vehicles were damaged or destroyed as well. A large quantity of sediment and debris was carried from the watershed and deposited along the affected stream reaches.

In May of 1996, less than two months before the July 12 flood event, a wildland fire burned about 12,000 acres of forested area in the Buffalo Creek vicinity. The fire burned intensely and quickly, leaving behind charred timber and a barren landscape devoid of vegetation and ground cover. The burned soils exhibited hydrophobic (water repelling) properties, and the burned area’s natural erosion control and runoff inhibiting characteristics were altered by the fire. Those conditions, in conjunction with a heavy rainstorm on July 12, were the recipe for disaster in Buffalo Creek.

Peak discharges for the July 12 event for the North Fork, Buffalo Creek, Sand Draw, and other tributaries were estimated by the Colorado Water Conservation Board and the USGS. The estimated flow rates on July 12 range from 4 to 25 times the published FEMA 100-year flow values.

Deaths and Damage: 2 deaths
Max. Precipitation: 2.0-2.5 inches within ~2 hours
Storm Center(s): Buffalo Creek, ~25 southwest of Denver



22 Ft. Collins
Video to be posted
July 28, 1997

This devastating flash flood, which has become known at "The Spring Creek Flood of '97," was the result of a series of very heavy thunderstorms which occurred over a two-day period in west Fort Collins. The event began on the evening of Sunday, July 27th. Heavy rains continued throughout the night, bringing 4 and 6 inches of rain to western portions of the urban area. The ground was totally saturated when a second round of even heavier storms formed in the same area on Monday evening. These storms were described as almost tropical in nature. Over 10 inches of rain fell between 5:30 p.m. and 11:00 p.m. on July 28th. The resulting flooding of Spring Creek caused a moving freight train to derail and totally destroyed two fully occupied residential trailer parks. Five people were swept away and killed. The rainfall set records for the largest 1-day, 3-hour, and 6-hour precipitation totals at the CSU gage, even though it was not located at the center of the storm.

The Colorado State University campus alone suffered many hundreds of millions of dollars in damage to buildings and furnishings. The CSU library was hardest hit, losing much of its inventory of books and journals.

The development of the Fort Collins OEM Website as a public education tool is due in large part to this flood and its aftermath.

Deaths and Damage: 4 deaths, $100s of millions in damage
Max. Precipitation: 14.5 inches
Storm Center(s): Fort Collins, southwest side of town