FLOOD09313

• County: Denver
• Community: Denver
• Stream Name: Marston Lake North
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 10/1/1979
• Prepared For: Denver
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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1

I. SUMMARY

Alternatives Studied

The Study Area

There were five comprehensive alternative plans studied in the Phase A
report on Major Drainageway Planning for Marston Lake North. Alterna-
tive 1 represents the "do nothing" alternative. In Alternatives 2
through 5 are included possible improvements to the existing drain-
ageway which are made up of various combinations of channels, culverts
and detention/storage facilities. More specifically they consisted of
the fo 11 owi ng:

The Marston Lake North drainage basin consists of approximately 2.1
square miles of limited developed area in the southwest corner of the
City and County of Denver. The basin originates at a point about one-
half mile west of South Kipling Street between Be11eview and Quincy
Avenues, and extends approximately four miles in a northeasterly
direction to its confluence with Bear Creek at Bear Creek Park. The
basin is long and narrow in shape, with a length-to-width ratio of
about eight. The basin is mostly open space, but is rapidly becoming
urbanized in the areas west of Colorado State Highway 121 (Wadsworth
Boulevard), with the predominant development being residential and
light commercial.

A lternat i ve 1:
to the existing

The "do nothing"
drainageway.

alternative considered no alterations

Alternative 2: This alternative considered no detention facilities
along the drainageway through all three reaches. Channel and culverts
were used as the major stormwater drainage conveyance.

Marston Lake and Marston Filtration Plant are owned and operated by the
Denver Water Board and serve as a major link in the water supply
system for the City of Denver and much of the metropolitan area. The
lake forms the southern border of the drainage basin along the middle
reaches of the drainageway.

Alternative 3: Lakes Lake as a detention facility was considered in
this alternative for Reach 3 with channelization in Reaches 1 and 2.
To implement this alternative, the dam embankment would have to be
rebui lt and suffi c i ent 1 and for the flood pool woul d have to be
acquired.

.
Lakes Lake, which lies in the upstream portion of the basin, has pro-
tected downstream reaches from flooding in the past. With the el imi-
nation of Lakes Lake and increased development west of Colorado State
Highway 121, stormwater flows will continue to increase causing
flooding to increase in severity and frequency.

Alternative 4: This alternative considered no detention at Lakes Lake
and considered the development of a detention facility at the sump
upstream of Colorado State Highway 121 and additional detention at the
Marston Sump. Channel and cul verts were used as the major stonnwater
drainage conveyance for Reaches 1 and 2.

The downstream reach of the drainageway traverses various jurisdic-
tions and ownerships, including Pinehurst Country Club golf course,
Fort Logan National Cemetery, and Bear Creek Park.

Alternative 5: This alternative considered Lakes Lake and Marston
Sump as storm detention facilites with channelization downstream of
these detention sites.

In analyzing solutions to flood control planning in the Martson Lake
North drainage basin, the basin was divided into three reaches: Reach
1, Bear Creek to Quincy Avenue; Reach 2, Quincy Avenue to Colorado
State Highway 121; and Reach 3, upstream of Colorado State
Hi ghway 121.

Recommended Alternative

In reviewing the benefit/cost analysis and the interests of local
governments and private property owners during the Phase A study, a com-