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

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In passing through the City, the waters undergo rapid warming because of

their water requirements, the aspen are present only in areas situated

the small volume, flat bottom, and shallow depth; this is especially

close to the streambed, while the pines are scattered on the adjacent

true in the open, developed areas. The dissolved oxygen, free carbon

slopes. Native grasses persist where undisturbed. Shrub growth is

dioxide, bound carbon dioxide, hydrogen-ion concentration (pH), sus-

almost nonexistent.

pended organic and inorganic matter, dissolved organic and inorganic

matter, and temperature are all parameters which should be carefully

The riparian ecosystem of Boulder Creek in the Boulder area has three

observed. If any problems arise with any of these factors, they must be

dominant woody species in close association as the stream passes through

rectified if Boulder Creek is to maintain its present ecological condition

the City of Boulder. The plains cottonwood is the most abundant with

in the future. New problems in the form of increased runoff from storm

many standing 60 to 80 feet high. The shade provided by these natural

sewers and the influx of residues from pesticides, herbicides, and

trees varies from 48 to 82 percent and complements the natural setting a

rodenticides could create added, more serious sources of pollution.

great deal. Various species of willows 1 ine the stream and scattered

clumps serve the animal population well by providing food, cover, and

Without the project, the aquatic environment of Boulder Creek should not

protection. The box elder, although not abundant, is also encountered.

change significantly in the foreseeable future if future pollutants are

Many other species of trees are present in varying numbers such as black

kept from the watercourse and if loss of shading is prevented. If the

locust, green ash, chokecherry, crabapple, Russian olive, juniper and

stream environment remains stable, the bottom fauna, aquatic inver-

pinon. The understory is varied with well established native and exotic

tebrates, and the fish population would continue to contribute to the

species. Since the stream flows through the center of Boulder, many

enhancement of Boulder Creek. Maintenance of an appreciable flow rate

private residences are situated along its course. There has been some

is the major factor in retaining the stream's present ecological equilibrium.

replacement of the native vegetation with lawns and city parks. Flower

beds have been planted wherever convenient; combined with the native

The present water rights, if upheld and maintained, would insure at

vegetation, they enhance the environmental setting.

least a 4 c.f.s. future flow rate. Infringement upon this establ ished

flow rate would occur only if extremely dry conditions existed over an

Stream-side tree growth from the canyon mouth downstream to 28th Street

extended period of time.

is fairly dense and in most places the trees form a complete canopy over

the creek. The vegetation is characterized by an overstory of 60- to

FLORA

80-foot plains cottonwood, peach-leaved willow, and green ash. Under-

The vegetative community upstream from the Canyon mouth at the west edge

story plants, although sparse in many locations, include thin-leaf

of Boulder is I imited primarily to pondorosa pine and aspen. Due to

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