FLOOD04566

• County: Boulder
• Community: Boulder
• Stream Name: Gregory, Bear Can, Bluebell Can Creeks, Viele Chan
• Basin: South Platte
• Title: Major Drainageway Planning Volume 1, Part C
• Date: 9/1/1970
• Prepared For: Boulder County
• Prepared By: CWCB
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Several examples of flooding in the South Boulder area are shown on the
following photos. For Bear Creek Canyon, the Boulder Dally Camera for
May 7, 1969, reads, "severest basement flooding was in the areas of Moor-
head Drive... and Table Mesa Drive...". For May 8,1969, it reads,
"motorists were still bei ng routed around the intersection of Table Mesa
Drive and Broadway, where Bear Creek raged out of its banks, flooding
the entire area Wednesday". Photos show this intersection of Table Mesa
Drive and Broadway.

Recurrent flooding conditions exist along Gregory Creek. The Boulder
Tribune for June 1, 1894 states that "Gregory Gulch has poured a flood
of water into the stream (Boulder Creek) from the beginning to the
present."

The U.S. Geological Survey in Flood Report Summary, Boulder Creek in
Boulder, Colorado, April, 1960, said "Field inspection indicates that
areas contiguous to Gregory Creek will also be inundated by large floods
on that stream."

William B. McDowell in A Plan - Boulder Report, dated October 26, 1961
states "Lesser streams not covered by the Flood Report (USGS, 1960), such
as... .Gregory, Bluebell, Skunk, and Bear Creeks are know.. to have flooded
in the past. They may be a principal cause of future concern because of
numerous violations of good drainage practice such as small culverts and
various forms of channel encroachment." In the past 9 years poor prac-
tices continued in an unabated fashion.

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Field observation of Gregory Creek during the May, 1969, Boulder flood
showed that some residences were flooded and streets overtopped even
though the runoff was for less than that produced from the 100-year flood.
Photos show a scene on Gregory Creek on May 7, 1969.

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No records of flooding problems for Bluebell Canyon Creek or King Gulch
were found. That they do exist was evident from the May, 1969, Boulder
flood. Field inspection showed that water from Bluebell Canyon Creek
crosses 15th Street and conti nues down Mariposa Avenue, out of its nor-
mal channel. This water is hazardous because of high velocities.

There has been some interest in flooding along Skunk Creek as its basin
was urbanized. The National Bureau of Standards Laboratory in 1959 asked
the Corps of Engineers to look at flooding problems along Skunk Creek
and recommend protective measures for their property. The ability of
Skunk Creek to carry its flood waters along this reach is determined,
"because of the limited discharge capacity of the culverts...". These
culverts would pass only 20'10, or less, of the 100-year flood, according
to the Corps of Engineers. The flooding hazard is increased somewhat
by the small dams in the vicinity of the National Bureau of Standards.
The Corps of Engineers says, "Overtopping will subject the dam to fail-
ure, and may result in a damagIng flood wave downstream".

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