FLOOD00850

• Designation Number: 31
• County: Arapahoe
• Community: Unincorporated Arapahoe County
• Title: Major Drainageway Planning - Little Dry Creek, Report, Volume I
• Date: 2/1/1974
• Designation Date: 6/1/1974
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Upper Little Dry Creek in Arapahoe County. From its confluence with Willow

Creek to Quebec Street, the creek channel is well-defined, steep, but sel-

dom straight. There are no trees along the banks. While the soil is soft

and clayey, indigenous grasses and brush generally minimize erosion except

on sheer banks. About 1,300 feet downstream from Arapahoe Road erosion at

a particularly steep 100-foot reach has been checked by large quantities of

dumped rock. Under present conditions both the bridge at Holly Street and

the pipe culverts at Arapahoe Road will not pass lOO-year storm runoff and

the roadways will be overtopped. Between Holly Street and Quebec Street,

the channel passes through land planned for development by S.M.S. Joint

Venture, except for the 1,300-foot reach mentioned above.

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From Quebec Street to Yosemite Street the steep, fairly straight creek chan-

nel is contained in an almost treeless, broad ravine without flood plains.

This 6,OOO-foot reach has one box culvert at Quebec Street and pipe cul-

verts at four other street crossings. Playgrounds have been developed

through the homesite area along the channel. A number of low check drop

structures have been built at these places to slow the velocity of the dry

weather low flows.

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Willow Creek in Arapahoe County. From its confluence with Little Dry Creek

to the face of the Englewood Dam, Willow Creek is a shallow, grassed chan-

nel that has been naturally formed in broad, undeveloped flood plains. A

bridge on Holly Street and a 60-inch culvert on Arapahoe Road are the only

two obstructions in the mile-long reach. If the intersection of Holly

Street and Arapahoe Road is to be developed in the future and be open during

lOO-year flooding, the Arapahoe Road culvert should be substantially enlarged.

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The crest of Englewood Dam is presently 30 feet higher than the ground sur-

face upstream. Indications are that about 7 feet of silt has been deposited

at the heel of the dam over the last 36 years. A sediment survey made in

1956 by the Soil Conservation Service indicated the reservoir had lost 70

acre-feet of storage capacity.* For a half-mile upstream from the dam, the

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* U.S. Corps of Engineers, 1968, "Flood Plain Information, Volume IV,"
Denver, Metropolitan Region, Colorado, P. 14.

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