FLOOD06039

• Designation Number: 124
• County: Boulder
• Community: Unincorporated Boulder County
• Stream Name: Dry Creek
• Basin: South Platte
• Title: Floodplain Information Report - Dry Creek, Boulder County-Weld County, CO
• Date: 6/1/1978
• Designation Date: 11/1/1978
• Floodplain - Doc Type: Floodplain Report/Masterplan

PAST FLOODS

SUMl-1ARY OF HISTORICAL FLOODS
Little peak discharge Information for potential floods on
Dry Creek was located during the study. This apparent lack of infor-
mation Is due to the limited amount of stream gaging data available.

FLOOD RECOf:lDS
No stream gaging stations were located on Dry Creek which
have recorded flood peak discharges. Information concerning past
flooding along Dry Creek was obtained from the Corps of Engineers,
the Colorado Water Conservation Board, Boulder County, Weld County,
and the Pioneer Huseum In Longmont, Colorado.

FLOOD DESCRIPTIONS
Little Information Is available relative to historic flood-
Ing on Dry Creek probably because of Its rural nature which has
resulted In little flood damage during flood events. Information
Is available, however, on adjacent streams which Indicate that flood-
water may have been experienced on Dry Creek. The fol lowing are
accounts of some of the heavy rainfal I events Which have occurred In
the Dry Creek area.

May-June 1894. Heavy rains fell on 29 May-2 June over the
mountains and plains extending from the Colorado-Wyoming border south-
ward Into the Republican and Arkansas River basins. Rainfall amounts
over the high plains gradually decreased from west to east varying
from 5 Inches at Boulder to approximately 2.5 Inches at the mouth
of Boulder Creek.

June 1921. Heavy general rainfall occurred from 2 June-
6 June over the South Platte River basin with the greatest amounts

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along the foothills of the Rocky Mountains. Rainfall covered an
area of approximately 520 square miles. The maximum recorded rain-
fall was 5.29 Inches and the greatest recorded ralnfal I Intensity
was 4.3 Inches In 6 hours at Longmont. Ralnfal I totalled 3.36
inches at Boulder.

August-September 1938. Heavy rainfall occurred from 31
August to 4 September over al I of eastern Colorado. Boulder reported
3.62 Inches of precipitation from 31 August to 4 September with 2.32
Inches fal ling during 2 September.

August 1951. On the afternoon and evening of 3 August,
very heavy rainfall occurred along 50 miles of the Front Range and
foothills from Boulder to Fort Collins. Unofficial reports Indi-
cated 6.3 Inches of precipitation occurred near Lyons and more than
6 Inches occurred southwest of Nlwot. A flood peak determination
of 5,700 c.f.s. on Dry Creek was obtained about 1.5 miles south of
Nlwot. The crest of the flood occurred about 9:50 p.m. on 3 August.
The flood swept across U.S. Highway 287, 2 miles south of Longmont,
at about 10:45 p.m. The flood on Dry Creek, which was 1/4 mile wide
In places, swept away crops, buildings, and equipment and required
the evacuation of about 50 people. Railroad and highway embankments
and bridges were washed out. The photographs of figures 13 through
16 show some aftermath of this flood.

May 1969. Heavy ralnfal I with a relatively long duration
occurred from 4 May until 8 May. The storm covered an area along
and near the eastern slopes of the Rocky Mountains and extended Into
portions of the high plains. The heaviest amounts were centered 25
miles southwest of Denver and extended In a band along the foothills
of the Rocky Mountains northward to Estes Park. Rainfall amounts of
7.60 Inches were reported at Boulder.

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