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

II
I

I

close to the channel. A low dike forms a tail water pond for the Blackmer
Lake outlet.

I

Blackmer Lake lies below a loop in the Highline Canal and covers 7.5 acres

when full. The top of the dam is 22 feet above its tailwater level. A

3-barrel, 660 cfs siphon spillway goes into operation when the lake level

rises. The old dam embankment was repaired and modified in 1937. Two small

tributaries originally joined at Blackmer Lake. The Highline Canal presently

intercepts low flows from these tributaries. Only the northern tributary

channel was studied upstream of Blackmer Lake.

I

I

I

I

Between the Highline Canal and Holly Street, the channel is interrupted by

three 7-foot high dikes forming private ponds used for the storage of irri-

gation water, The reach has an unusually heavy growth of weeds, cattails,

and mature trees. Adjacent homes are out of the flood plain.

I

I

From Holly Street to a line of extension of South El Camino Drive a paved

road has been built in the bottom of the waterway. Shallow ditches convey

annual frequency runoff to a 24-inch culvert under Holly Street, but a 10-

year or larger storm inundates the paved street and the low part of Holly

Street. The storm in May 1973 partially washed out Holly Street at this

location. The waterway reach is clear of obstructions.

I

I

I

The last reach of Blackmer Gulch between a line of extension of South El

Camino Drive and Charlou Drive, an extension of Monaco Street, is steep but

well covered with prairie grasses. No obstructions exist. An l8-inch

culvert under Charlou Drive is completely plugged with soil that has been

eroded and transported by runoff.

I

I

I

Quincy Gulch in Cherry Hills Village. Dry weather flow from Quincy Gulch is

conveyed in a small, shallow roadside ditch that enters Blackmer Gulch at

Random Road. Roadside ditches are used to convey low flows for at least

1,500 feet upstream; however, no well-defined natural channel exists and

under present conditions 10-year and greater runoff will flow over the area

in a wide shallow band. From the confluence of Quincy and Blackmer Gulches

I

I

-24-

I