South Platte &
Arkansas Basins:

July 25 & 30-31, 1998

The end of July 1998 was filled with violent, wet weather concentrated over the southern and central Front Range. The region had experienced a month with above-average precipitation and in most areas the ground was already saturated by monsoon. The first two intense storms hit Idaho Springs and the Denver metropolitan area on the evening of July 25. Both systems were fast moving and dropped a large amount of precipitation over a concentrated area in a very short time. On July 29-30 “massive” thunderstorms hit El Paso, Douglas, and Denver Counties. On July 31, heavy rains hit Buffalo Creek in southern Jefferson County and another violent, slow-moving thunderstorm pummeled Custer County near the town of Westcliffe with heavy rains and large amounts of hail.

The storms on July 25 caused mostly overland and rainwater flooding in Denver, although a spillway from the Cherry Creek Dam to the High Line Canal overflowed and there were reports of creeks and rivers in the metropolitan area overflowing their banks. In Idaho Springs, the rains caused a flash flood in Virginia Canyon and rainwater flooding in town. On July 30, rainwater and overland flooding occurred in Security, Calhan, Denver and other areas. On July 31, river flooding occurred on Buffalo Creek, Spring Creek and the Platte River.

In the South Platte drainage on July 25, torrential rains caused mudslides on County Road 279 between Idaho Springs and Central City. Several cars were washed off the road, which was closed for two days to clear off the debris. In Idaho Springs, numerous basements were flooded and the floodwaters left up to six inches of mud in some areas.

In Denver, interstates 25 and 70 were both closed for several hours due to high water in low lying areas. In Englewood, U.S. 285 was closed at Santa Fe Drive due to nine cars that were bobbing up and down in the floodwaters. In Aurora, at the intersection of Yale and Chambers, floodwaters were up to 4 feet deep after a spillway on the High Line Canal was breached. A few drivers were rescued from their vehicles after they became trapped by water cascading over their hoods near the South Platte River. Across the metropolitan area there were numerous reports of power outages, stalled vehicles and basement flooding.

On July 30 in Denver, I-25 was closed at Logan Street for several hours due to flooding when a 2-inch rainfall in one hour overwhelmed drainage systems. Underneath the Logan Street Bridge, the water was nearly 5-feet deep. The intense rainstorms also caused flash flooding problems from Castle Rock to Parker. North of Castle Rock, I-25 was closed due to flooding on the highway. Some vehicles were left floating in the floodwaters.

West of Denver on July 30-31, the rainstorms caused costly damage in two mountain communities. Heavy rains “pushed a river of mud, trees and boulders through Main Street ” causing major damage to the Golden Gate Casino in Blackhawk. About 100 people were evacuated. In addition, portions of County Road 126 south of the town of Buffalo Creek were washed out and the creek also caused major damage to a bridge.

In the Arkansas River drainage the hardest hit area was Security, where the heaviest rain fell on July 30. Numerous intersections in the town were flooded with as much as 2 to 3 feet of water. The Security Fire Station was flooded, as well as several other businesses. Some homes had flooded basements and the rain washed away fences and landscaping. The floodwaters left up to a foot of sand and mud in low-lying areas.

In the Calhan area in Elbert County, more than a dozen bridge approaches were washed out. Heavy rains caused a mudslide north of Manitou Springs that blocked Highway 24. A group of teenage hikers had to be rescued after a downpour stranded them in Queens Canyon.

In Custer County, the intense rains washed out parts of Highway 255 northeast of Westcliffe on July 31. Standing water and piles of hail blocked several other roads. The hail was so deep, the Colorado Department of Transportation had to clear the roads with snowplows.

Rainfall Data:

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