FLOOD10390

• County: Boulder
• Community: Boulder
• Stream Name: Fourmile Canyon
• Basin: South Platte
• Title: Fourmile Canyon Creek - Major Drainageway Planning - Phase A Report - Alternatives Analysis
• Date: 6/1/2000
• Prepared For: UDFCD, Boulder
• Prepared By: Love & Associates
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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Debris Removal

Woody debris is a habitat component in riparian ecosystems. Downed trees, which are anchored in
the channel, may create scour pools that enhance fish habitat. One anchored tree at the downstream
end of the study area has created a blockage, which appears to have contributed to the development of
a wetland. While woody debris diversifies wildlife habitat, it also blocks flood flows. Regular debris
removal is a standard maintenance practice on flood conveyance channels. It is recommended that
prior to debris removal, an inter-disciplinary team of engineers and biologists identify and map debris
to be removed and preserved.

to one bank may be appropriate to minimize

to ensure

grubbing

or

excavation

Where feasible, limiting flood channel
impact to existing trees.

General Construction Recommendations

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in order to

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REFERENCES-CHAPTER 7 ONLY

7.7

quality

for harvest of

water

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Assessment

Riparian Habitat

Draft, 64 pp

Tributary Greenways

Master Plan Update,

(1998)

City of Boulder, Planning Department
Map, Draft.

Greenways

City of Boulder (1999)

late June to maximize

mid-May to

.

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Secondary ,and

Primary,

(no date)

Services

City of Boulder, Water Quality & Environmental
Tertiary Aquatic Habitat Criteria Maps.

Ecosvstem Mana2ement

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Habitat

Program Riparian

Gershman, Mark (1999): City of Boulder Tributary Greenways
Assessment, Vegetation Evaluation Final Report.

its Tributaries,

Library of Congress

City of Boulder Tributary Greenways Program Riparian Habitat Assessment Bird

Stream Habitat Assessment Report for Boulder Creek and

Hydrology,

Wildland

Morphology,

River

Rosgen, Dave, (1996): Applied
Catalog Card Number: 96-60962

Stone, Eric (1999)
Inventory, 16 pp

Tamara J (1995)

Laninga,
10 pp

Maintenance responsibilities of riparian areas has been a point of confusion among private property
owners and various City of Boulder (City) departments. The City is currently in the process of
defining maintenance responsibilities and planning for active management of the tributary greenways.
Excavation of a flood channel on Fourmile Canyon Creek will require that land acquisition and
easement agreements be executed between the City of Boulder and private parties. These agreements
may provide a vehicle for assigning vegetation management and weed control responsibilities to the
public sector throughout the corridor. This would ensure integrated management of the stream
ecosystem.

Vegetation Maintenance Responsibilities

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The following methods are recommended to minimize construction impacts:
. Require fencing of limits of construction prior to staging, clearing,
protection of preserved vegetation
No construction activity should be allowed within the drip line of preserved trees
minimize damage to the root structure and associated delayed mortality
Implement and maintain erosion control measures to prevent degradation of
during construction
Utilize healthy plant communities within the study reach (local genetic material)
native wetland and riparian plant materials
Where possible, complete final grading of riparian terraces
volunteer cottonwood establishment

Benthic

Rivers

and

Protocols for Use in Streams
Publication, 194 pp

Rapid Bioassessment
and Fish, National Environmental

U.S EPA (1989):
Macroinvertebrates

Vegetation Management

Regardless of which master plan alternative is selected, active management of the Fourmile Canyon
Creek ecosystem is needed to maintain and enhance habitat quality and prevent further degradation.
Planting native species, removing invasive species, thinning or removing exotic species in the
understory, and developing and implementing a weed control plan are essential components of
vegetation management. Weed control and control of invasive exotics are particularly important in
the first few years following any disturbance, including flood improvements construction. Protection
of plantings from browsers such as deer and beaver, and from vandalism until established is also
critical. Flood channel excavation presents the opportunity to establish a broader, healthier,
diverse native riparian community than currently exists in the project area. However,
vegetation management following construction is essential to success

more
active

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7-1

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