FLOOD10420

• County: Adams
• County: Broomfield
• County: Weld
• Community: Broomfield, Westminster and Thornton
• Stream Name: Lower Big Dry Creek
• Title: Lower Big Dry Creek Hydrology Study
• Date: 6/1/2005
• Prepared For: Big Dry Creek Watershed Association
• Prepared By: Wright Water Engineers, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Lower Big Dry q:reek Hydrologic Study

drops, laying back streambanks, a trail and ablut 400 plantings for a cost of about $800,000. The
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partnership funding these improvements included the Botanic Gardens, the Army Corps of
Engineers, Jefferson County, UDFCD and Lockheed-Martin and others. Lockheed Martin
funded a significant portion of the improvements because they received phosphorus reduetion
credits. Additionally, the watershed assobiation members have recognized it is better to
pro actively control erosion rather than let it Igo unchecked, resulting in more costly restoration.
They have emphasized the importance of Jovernmenta1 staff proactively communicating this
message to elected officials and have also uJed the A W ARE program developed by the League
of Women Voters (Personal Communication lith Russ Clayshulte).

7.2.3 Rock Creek. Boulder. Colorado

Rock Creek is located just north of the Big Dry Creek watershed and has experienced a similar
type of stream erosion. Recently, volunteerJ undertook a five-month erosion control project in
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the Carolyn Romberg Preserve. Wildlands Restoration Volunteers planted native wetland
grasses and sedges to stabilize the banks aloJg severely erode portions of the creek. The erosion
is attributed to runoff from upstream bUi1dinks, parking lots and roads that have led to incre:ased
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runoff. Boulder County partnered with UDFCD to fund about $800,000 of strearribank
stabilization improvements including five doncrete drop structures, shaping the streambanks,
stabilizing the banks with coconut-fiber rollJ and revegetating the creek (Boulder Daily Camera
2005).

7.3 New Approaches to Improve Current Stormwater Management Practice

While the state of the practice generally reliJ on detention facilities to control peak flows from a
few key design storms (as discussed in Secti10n 7.1), several national storm drainage experts are
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exploring refinements and improvements to these practices. Three approaches that have potential
application to Big Dry Creek are described bJ10w and include:

. Nebrke and Roesner (2004): desiJing facilities to better match the flow,frequency

curve.

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. Wulliman and Urbonas (2005): imp1~menting full spectrum detention designs
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971-179.092 Wright Water Engineers, Inc.
June 2005 I
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