FLOOD05827

• County: Boulder
• Community: Boulder
• Stream Name: Boulder Creek
• Basin: South Platte
• Title: Boulder Creek Phase B
• Date: 12/1/1979
• Prepared For: Boulder
• Prepared By: UDFCD
• Floodplain - Doc Type: Floodplain Report/Masterplan

In 1977, the Corps of Engineers prepared a draft report on Boulder

Creek for the Metropol itan Denver a~d South Platte River Study.

The hydrology and hydraulics prepared as part of this Study are

The plan authorized by the Flood Control Act of 1950 includes

improvements on Boulder Creek through the city and on the lower

portion of Sunshine Creek, a minor tributary at the west end of the

city. Proposed improvements along Sunshine Creek include an exca-

vated channel with revetted banks extending 1,500 feet upstream

from its mouth. Boulder Creek improvements would consist of chan-

nel straightening and widening, bank revetment, concrete floodwalls

and, at the request of local officials, a proposed elevated boulevard

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

In 1972, the Corps of Engineers prepared a Special Flood Hazard

Information Report. This report together with the 1969 Corps of
Engineers report formed the basis for Boulder's participation in

the emergency phase of the Federal flood insurance program.

being used by the Federal Insurance Administration (F.I.A.) to

develop the necessary information to qual ify Boulder for inclusion

in the regular Federal insurance program. The hydrology of the

Boulder Creek Basin was restudied in conjunction with this report

using the Environmental Protection Agency's Storm Water Management

Model (SWMM). Historical stream gaging records were used to check
the result obtained from the SWMM. The results of the restudy

revised the estimated 100-year discharge at Boulder from 7,400

c.f.s. to l2,000 c.f.s. This report contains three feasibility

studies for flood control improvements on Boulder Creek; Plan I

based on an enlarged channel, Plan I I based on an excavated flood-

way, and Plan I I I based on flood-proofing and relocation. Plan I I I

represents the plan favored by the Boulder Creek Subcommittee.

In 1970, the Corps of Engineers prepared a Reconnaissance Report

for Boulder Creek.

In October of 1973, the Boulder Creek Subcommittee of the Corps of

Engineers Committee on Environmental Planning (CECEP), a citizens

group formed to advise the Corps of Engineers on local and environ-

mental issues affecting the authorized project, outlined a II-point

flood control plan as an alternative to plans developed by the

Corps of Engineers. The proposed Il-point flood control plan

advocated by the Boulder Creek Subcommittee was based on an aggres-

sive land use management program coupled with minimal structural

improvements to protect bridges and streets.

Many local plans have been developed for flood control improvements

on Boulder Creek and its tributaries. These include Boulder Creek

from 9th to 14th and 24th to 30th Streets, Wonderland Creek, lower
Sunshine Gulch and South Boulder Creek.

In May of 1974, Frazier and Gingery Inc., a consulting engineering

firm, prepared floodway maps for the City of Boulder based on a

100-year discharge of 7,400 c.f.s. covering the reach of Boulder

Creek from the canyon mouth downstream to Valmont Road.

30