WSPC01371

• File Number: 8200.300.20 C
• Description: Colorado River Basin - Legislation-Law - Federal - Colorado River Floodway Protection Act
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/30/1989
• Title: Report of Colorado River Floodway Task Force
• Water Supply Pro - Doc Type: Report/Study

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002245

CHAPTER VI

DRAFT
August 30, 19B9

RECOMMENDATIONS ON AND THE REVIEW OF MAPPING PROCEDURES FOR
THE FLOODWAY BOUNDARIES.

The location of the Floodway boundaries at any specific
location along the river is determined by an analysis of the
one-in-one hundred year flow rate (or 40,000 cfs) and the
physical characteristics of the river channel. The process
for determining the Floodway boundaries was discussed in
Chapter V of this report. The identification of these
boundar ies on a specif ic off icial set of maps is a key
product resulting from the Floodway Act. The Floodway maps
shall be considered a standard map to be adhered to by all
agencies and shall have the same force and effect as if
included in the Act. The communication of these boundaries
to involved federal, state, and local governments as well as
private landowners and businesses is essential to
accomplishing the purposes of the Act.

The portion of the Colorado River from Davis Dam to the
Southerly Boundary between the United States and Mexico is
some 276 miles in length. The width of the area impacted by
the Floodway boundaries varies from about 450 feet to BOO
feet, whereas the width of the Floodway Fringe varies from
zero feet to approximately one mile. The Act requires that
the "Secretary shall provide copies of the Colorado River
Floodway maps to (A) the chief executive officer of each
State, county, municipality, water district, Indian tribe, or
equivalent jurisdiction in which the Floodway is located, (B)
each appropriate Federal agency, including agencies which
regulate Federal financial institutions, and (C) each
federally insured financial institution which serves the
geographic area as one of it primary markets." The maps
should be of a style and with sufficient detail to be useful
to the broad range of users. At the same time, the scale
must be such that the maps can be reproduced and bound into
practical working documents.

The Working Committee and Technical Subcommittee of the
Task Force that worked to develop specific design criteria
for creation of Floodway boundaries also worked to develop
and review the mapping procedures. Appendix G of this report
provides a summary explanation of the procedures and

VI-l