PDF (53.8 MB) - Urban Drainage and Flood Control District

Muller Engineering Company, Inc.
Happy Canyon Creek Major Drainageway Plan - DRAFT
Table 2-1
Major Crossing Inventory
Crossing Location Reach Type
Oak Hills Drive Reach 2 – Douglas County South Double 6’x8’ Box Culvert
Clydesdale Road Reach 2 – Douglas County South Double 72” CMP Culvert
Interstate 25 Reach 3 – I-25 Corridor Single Span Bridge
I-25 Frontage Road Reach 3 – I-25 Corridor Single Span Bridge
Ridgegate Parkway Reach 4 – Lone Tree South Single Span Bridge
West Parker Road Reach 6 – Lone Tree North Double Span Bridge
Lincoln Avenue Reach 6 – Lone Tree North Triple Span Bridge
Birch Avenue Reach 7 – Grandview Estates Double Span Bridge
Dogwood Avenue Reach 7 – Grandview Estates Triple 48” CMP
E-470 Reach 8 – Compark Two Single Span Bridges
Chambers Road Reach 8 – Compark Single Span Bridge
Jordan Road Reach 9 – Arapahoe County Single Span Bridge
desire to protect this reach in as natural a state as possible, not only for habitat benefit, but also for
water quality through a meandering riparian ribbon. The upper zone, from Castle Pines to I-25, was
seen as less valuable to wildlife than the middle zone, with less extensive riparian vegetation in the
ponderosa pine forest. Wetland vegetation within Castle Pines seems to have increased substantially
since this time. Overall, the value of maintaining a preserved open space corridor through the
drainageway was emphasized for the benefit of wildlife habitat. This approach is in line with the
local jurisdictions’ policies of floodplain preservation and creation of open space corridors.
No federally threatened or endangered species have been identified within the project area;
however, a project site-specific review should be conducted prior to implementing any
recommended improvements. In addition, any work along the creek corridor should consider nonprotected
species in the area and avoid impacts during sensitive periods such as nesting/mating
season.
2.4 Flood History
There is limited information on history of flooding along Happy Canyon Creek, though there are
many published accounts of flooding on nearby Cherry Creek. Much of the Happy Canyon Creek
channel is located within open space tracts that provide adequate floodplain capacity; areas of flood
concern are primarily located within Grandview Estates. Residents mentioned various high flow
events causing overtopping of local streets and/or flood waters approaching their homes over the
years; the 1993 OSP indicates previous accounts of road overtopping during heavy rainfall events.
There are no stream gages on Happy Canyon Creek.
2.5 Environmental Assessment
Wetland zones are present along much of Happy Canyon Creek, though they markedly decrease in
the downstream portions of the watershed where there is no base flow. An inventory of wetland and
riparian areas is included in Appendix E.
The 1993 OSP includes correspondence from the Colorado Division of Wildlife (DOW) regarding
wildlife habitat within the watershed. The DOW described three different zones of vegetation with
varying wildlife value. The lower zone, from Lincoln Avenue to Cherry Creek, was described as
relatively dry with sparse riparian vegetation and only marginal wildlife value. The potential for
creation of wetlands was noted, as the floodplain is wide and open. The middle zone, from I-25 to
Lincoln Avenue, was described as the most valuable reach for wildlife, with “a broad band of riparian
vegetation including an abundance of willows and cottonwoods.” The DOW commented on the
August 2013 Page 2-6 Alternative Analysis