WSP06003

• File Number: 8449.900
• Description: Bear Creek
• State: CO
• Basin: South Platte
• Date: 11/1/1991
• Author: City of Lakewood
• Title: Bear Creek Lake Preliminary Environmental Assessment Wetland Task Report
• Water Supply Pro - Doc Type: Publication

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

ES ENGINEERING-SCIENCE

and surrounding areas. The map scale was 1:2400, and the contour interval was 2
feet. The inundation level of Scenarios A. B, C, and D is 5,554, 5,574, 5,576, and
5,585 feet, respectively. Given that the existing permanent pool elevation is 5,558
feet, the inundation area will increase with Scenarios B, C, and D and decrease with
Scenario A.

Preliminary locations and boundaries of jurisdictional wetlands and riparian
areas were also plotted on the same topographic maps. Inundated areas were
locations below the pool elevation contour. Inundated wetland and riparian areas
were measured using a polar planimeter. The planimetered area was converted to
acres using mathematical conversion factors and rounded to the nearest 0.1 acre.
Inundated areas were tabulated separately into five location categories (e.g., Bear
Creek wetlands and lakeshore wetlands) to demonstrate how different wetland
locations and types would be affected by each water storage scenario.

Wetland locations and boundaries were determined by comparing site conditions
in the field with aerial photography (approximately 1:4800 scale) and the
topographic maps. Approximately 90 percent of the maximum inundation area was
inspected in the field. Professional judgment was used in the field to estimate
jurisdictional wetland locations and probable boundaries. Efforts focused on
identifying jurisdictional wetlands because these sites would require permit action
by the Corps and U.S. Environmental Protection Agency (EP A) under Section 404
of the Oean Water Act. Judgment was based on experience gained mapping
jurisdictional wetlands (using the 1989 federal wetland delineation method)
elsewhere in the park for the proposed Fox Hollow at Lakewood Golf Course.
Jurisdictional wetland determinations were based on vegetation species composition
and the hydric status of those species. Because of the extensive overlap of most
vegetation and hydrologic factors in both jurisdictional wetland and riparian areas,
the composition and hydric status of the dominant herbaceous ground cover was
most often the distinguishing characteristic that determined a site's status as either a
wetland or riparian area. Herbaceous ground covers dominated by facultative,
facultative wet, or obligative species were considered probable jurisdictional
wetlands, while ground covers composed primarily of upland and facultative species
were considered either upland or riparian areas.

The terms facultative, facultative wet, and obligative describe how strongly a
particular plant species is associated with wetland conditions. Each pIant species is
assigned to one of five major indicator categories that range from always being
associated with wetlands to always being associated with non-wetlands. Wetland
conditions include the three categories listed. Obligative species occur almost
always (estimated probability of encountering the species in a wetland is greater
than 99 percent) in wetlands under natural conditions. Facultative wet species
usually occur in wetlands (estimated probability ranges between 67 and 99 percent),
but occasionally are found in non-wetlands. Facultative species are equally likely to
occur in either wetlands or non-wetlands (estimated probability ranges between 34
and 66 percent). Because detailed jurisdictional determinations were not included

-8-

Bl~~3