FLOOD00816

• County: Boulder
• County: Weld
• Community: Boulder, Weld Counties
• Stream Name: Dry Creek
• Title: Floodplain Information Report
• Date: 6/1/1978
• Prepared For: Boulder County / Weld County
• Prepared By: US Army Corps of Engineers
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

of timber especially adjacent to streams. Climate in the basin is
semiarid varying with the topography. In general, warm summers and
mild to cold winters prevail. Intense thunderstorms, sometimes of
cloudburst intensity, can occur during the summer months. The fol-
lowing table gives climatological data for the Dry Creek basin
vicinity.

Table 1
Dry Creek Basin Vicinity CI imatoiogical Datal!

.

Location

Mean Annual
Precipitation
(inches)

January Mean
Temperature
(of)

Ju Iy Mean
Temperature
(OF)

2 Miles East
Southeast of
Post Dff ice in
Longmont

12.74

71.6

26.8

Greel ey

12.20

73.3

24.5

Boulder

18.91

73.9

33.0

Waterdale
Located about
6 Miles West
of Love I and

15.82

70.0

28.8

11

This data was compiled from National Weather Service records
for 1941-1970.

Dry Creek is a right-bank tributary of St. Vrain Creek;
its source is in the foothills of the Rocky Mountains north of
Boulder, Colorado. Dry Creek flows In an easterly direction through
Boulder Reservoir Joining St. Vrain Creek about one-half mile down-
stream from the Boulder-Weld County line. The portion of Dry Creek
studied In this report begins about 3 miles northeast of Boulder
Just downstream from Boulder Reservoir and ends about 3 miles east
of Longmont near the Dry Creek and St. Vraln Creek confluence.

2

Throughout this reach, the channel width generally varies from 20
to 70 feet and averages 40 feet in width. The channel depth gen-
erally ranges from 2 feet to 10 feet and averages 5 feet. The
streambed has an average slope of 15 feet per mile through the
study reach. The Dry Creek channel is alluvial and meanders through
a val ley,whlch is generally "v"-shaped in the upper half of the study
reach and is generally "u"-shaped in the lower half of the study
reach.

Figures I through 12 show existing conditions along the
Dry Creek study reach. These photographs were taken In March 1978
by personnel of the Colorado Water Conservation Board.

DEVELOPMENT ON THE FLOOD PLAIN
Development on the flood plain within the study area is
relatively sparse. The most common form of development Is that
assocIated with farmsteads and an agricultural area. At present,
the more congested development assocIated wIth urban areas remaIns
external to the flood plain except in the vIcinity of Niwot where
some urban development has occurred in the flood plain.

3