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 preek Hydrologic Study

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Common themes and concerns expressed by landowners included:

. The late July and mid-August storm events of 2004 produced some of the largest flows
observed to date by the landowners, most of whom have either lived in the watershed for
their entire lives or at least the last 20f30 years, (Section 8.4 provides an analysis of these
storm events.). These storms caused extensive flooding, erosion and sediment deposition,
which was still evident at the time of {he spring 2005 visit, as shown in Appendix A.

Most landowners recognized that the hooding and erosion prohlems are not easily solved,
but would like action to be taken to p~event conditions from becoming worse in the future

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as upstream growth continues.

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. Several landowners asked whether some sort of upstream regional detention could be
implemented, with several noting thb role that the railroad embankment near Colorado
Boulevard plays. (This embankment is also noted in one of the master drainage plans.)
Weld County landowners downstream of this embankment benefit from this inadve:rtent
detention, while Adams County 11ndowners upstream of the embankment report
. d fl d' d h' . I .
mcrease 00 mg ue to t IS constnctlOn.

While erosion was evident thrOUghoJ long reaches of the creek, several landowners were
concerned about one key issue on tJeir property. For example, the Rosenbrocks, Tom
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Chikuma, Glenda Ira and Bob Green have property access issues when high water makes
their driveway or property bridges ilpassible or causes erosion to crossing structures.
Don Wright is primarily concerned lbout a steep cut bank that threatens his irrigation

ditch. The Wagner property has several hairpin-like bends that are experiencing
accelerated erosion. The Howards are concerned about the Y oxall Ditch headgate. Bob
Green and Glenda Ira both have brikge erosion or washouts limiting grazing property

access.

· Throughout the watershed, broken concrete placed by landowners along stream banks to
stabilize the banks was evident.

971-179.092
June 2005

Wright wr' Englnee.., Inc.

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