FLOOD06564

• County: Boulder
• Community: Boulder
• Stream Name: Goose, Wonderland, Elmer's Twomile, 2-mile, 4-mile
• Basin: South Platte
• Title: Major Drainageway Planning Volume 1, Part B
• Date: 4/1/1969
• Prepared For: Boulder County
• Prepared By: CWCB
• Floodplain - Doc Type: Floodplain Report/Masterplan

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SECTION II

THE STUDY AREA

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The pilot study area in North Boulder is an urban and urbanizing
series of drainage basins lying in Township 1 North, Range 70
and 71 West of the 6th Principal Meridian. The total tributary
area of the basins is 17 square miles. The elevations range from
5,160 feet at Boulder Creek to 8,500 feet at the western divide
of Fourmile Canyon Creek,

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The individual drainage basin areas are as follows:

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Goose Cree k
Wonder 1 and
Elmer's Twomi Ie Creek
Twomile Canyon Creek
Fourmile Canyon Creek

2.4 sq, mi.
2,2 sq. mi.
0.7 sq. mi.
2,0 sq. mi.
10,0 sq. mi,

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Of the five basins, only Twomile Canyon and Fourmile Canyon Creeks
originate in the foothills west of the hogback, Goose Creek and
Wonderland Creek originate at the hogback, and Elmer's Twomile
begins east of Broadway in a residential area.

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Twomile and Fourmile Canyon Creeks leave the foothills in rigid and
well defined channels. Over many centuries of flooding, tnese two
creeks have built up extensive alluvial fans at the canyon mouths
from sediment which has been washed down, On the alluvial fan, and
to the east, these two creeks often changed their courses while doing
nature's work of always cutting one place and fill ing another, Four-
mi Ie Canyon Creek had a defined channel to Boulder Creek when man
settled the area, the channel being about the same as it is today.

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Twomile Canyon Creek in about 1860 was a renegade even then, It
came out of the foothills and apparently spread out near the exten-
sion of Iris Avenue, west of Broadway,

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Goose Creek historically became a defined waterway in the area west
of the Community Hospital and coursed through the general location
of Joyce's Supermarket, continuing to the east and finally entering
Boulder Creek somewhat southeast of the old sewage plant.

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Wonderland Creek was similar to Goose Creek but had a longer way to
go before reaching Boulder Creek. It picked up Elmer's Twomi Ie
Creek near the Longmont Diagonal. Indications are that part of the
Wonderland Creek floodwaters reached a slough at 30th and Iris,
though the primary route was probably in the slough at 32nd and
Iris Avenue.

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Goose Creek and Twomi Ie Canyon Creek drain into fully urbanized
areas between the western boundaries of the City and about 28th

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