FLOOD01790

• County: Adams
• Community: Adams County
• Stream Name: Second Creek, Third Creek
• Title: Flood Hazard Area Delineation - Second and Third Creek
• Date: 2/1/1976
• Prepared For: Adams County
• Prepared By: UDFCD
• Floodplain - Doc Type: Floodplain Report/Masterplan

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11

study considers all flood flows to be carried across each ditch
and to be tributary to downstream reaches.

In the lowest reach of Third Creek, below the Henderson to
Brighton Road, the Third Creek flood plain is located within
the South Platte River flood plain. Both flood plains are
noted on Drawings TC-l through TC-4. Through this reach, Third
Creek is coincident with the McCann Ditch. The flood plain
area is almost totally open but does encompass some buildings
as shown on Drawing TC-3. Above the confluence with the South
Platte River 100-year flood plain, near Station 95+00 on Drawing
TC-4, the Third Creek 100-year flood plain inundates many buildings
in and around the Wagon Wheel Skating Rink. Some of the buildings
could be flooded by backwater from the South Platte River, without
flooding on Third Creek. The extent of the flood magnitude in
this area is increased as a result of the Second Creek flood
flow diversions discussed previously.

Above Chambers Road to Tower Road, the flood plain limit is

well defined. No improvements are located in the flood plain

except crossing structures at 104th Avenue and Irondale Road

and a high tension line tower upstream of 104th Avenue. Certain

areas subject to shallow flooding are noted on the maps. The

reach is shown on Drawings SC-14 through SC-20.

In the reach from Tower Road to the Urban Drainage & Flood Control

District boundary, the upper study limit, the flood plain encom-

passes natural, agricultural land. The only structural improve-

ments in this reach are Tower Road, East 64th Avenue, and a

breached reservoir embankment 1,500 feet above Tower Road. Both

the Tower Road and former reservoir embankments create backwater

conditions which tend to widen the flood plains. Throughout the

other parts of the reach, the flood plain limit is well defined.

This reach is shown on Drawings SC-21 through SC-34.

Third Creek - The 100-year flood plain limits and water surface
profiles for Third Creek are shown on the Flood Hazard Area
Delineation Drawings TCP-l through TCp-9 and TC-l through TC-34.
In the lower reaches, the flood profile drawings have been separated
from the flood plain maps to permit proper coverage of the full
extent of the flood plain.

Between the old and new alignments of U.S. 85, many residential,

commercial and church sites are included in the 100-year flood

plain. Due to the flatness of the terrain, the potential flooding

would be shallow, generally less than two feet. This area is

shown on Drawings TC-4 and Tc-5. Development pressures have been

and will continue to be strong in this part of the Third Creek

basin. The 100-year flood plain through this area has been

delineated upon the assumption that all flood flows tributary

to U.S. 85 will be passed downstream.

In the reach from new U.S. 85 to the Fulton Ditch, Drawings
TC-5 to TC-9, the flooding problem is complex and difficult to
exactly access. As reported previously, the Fulton Ditch, the