FLOOD10157

• Designation Number: 74
• County: Arapahoe
• Community: Aurora
• Stream Name: Granby and Sable Ditches
• Basin: South Platte
• Title: FHAD - Granby and Sable Ditches, Aurora, Colorado
• Date: 4/1/1977
• Designation Date: 7/27/1977
• Floodplain - Doc Type: Floodplain Report/Masterplan

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-2-

basin as determined from current master planning maps. Possible
future improvements to control floods are not a consideration
of this report.

STUDY AREA DESCRIPTION

Flood water surface elevations and flood plain boundaries are
often revised by road and bridge construction, flood plain
development, flood control improvements, or natural processes.
Prior to utilization of this report for planning or design
purposes, the user is advised to contact the Urban Drainage
and Flood Control District or the Colorado Water Conservation
Board to determine if the information in t~is report has been
amended.

The Flood Hazard Area Delineation Study reaches for Granby
Ditch and Sable Ditch are located completely within the city
limits of Aurora. Both ditches are tributaries of. Toll Gate
Creek with their confluence just west of 1-225. The study
area for Granby Ditch extends from Toll Gate Creek, approximately
2.5 miles upstream to the Laredo Street crossing. The study
area for Sable Ditch extends from Toll Gate Creek, approximately
1.8 miles upstream to near Colfax Avenue. The regional location
of Granby Ditch and Sable Ditch is shown on the title sheet
preceeding the Flood Hazard Area Delineation maps at the back
of this report.

The information in this report does not imply any state action
to zone or regulate use of flood plains. The District has the
authority to regulate flood plains, but to date has chosen
to leave flood plain regulation responsibility with local
governments. The report provides a suitable basis for the
adoption of land use controls to guide flood plain management,
with consideration for environmental attributes, and thereby
prevent intensification of flood losses.

Under the Basin Indexing System of the Urban Drainage and
Flood Control District, Granby Ditch Basin is designated as
1~.05-4404-1. Sable Ditch Basin is designated as Basin
1-01-4403-01. Both basins are located mainly in the City of
Aurora extending into Bukley Air National Guard Base.

The report was prepared by Gingery Associates, Inc., Consulting
Engineers, Englewood, Colorado, at the request of the Urban
Drainage and Flood Control District. Survey control data for
this study was also collected and compiled by Gingery Associates.
The topographical mapping was prepared by Kucera & Associates,
Inc., of Denver, Colorado. The survey control, mapping and
sutdy were completed under study agreements with both the
Urban Drainage and Flood Control District and the Federal
Insurance Administration.

Sheet 1 of 12, Basin Boundary, shows the drainage basin
limits of Granby and Sable Ditches. Elevations within the
Granby Ditch Basin range from 5300 feet at the confluence with
Toll Gate Creek to 5590 feet at the upper limits of the basin
inside Buckley Air National Guard Base. The maximum elevation
at the upstream limits of the Sable Ditch Basin is 5510 feet.
Traversing a length of approximately five miles, the average
stream gradient for Granby Ditch is approximately 48 feet
per mile. The total length of the Sable Ditch Basin is
approximately three miles and has an average stream gradient
of 54 feet per mile. Drainage areas at various points within
the basin are provided in Table I.

Acknowledgments