BOARD01965

• Board Meeting Date: 3/22/2005
• Description: Flood Section - Presentation of the CWCB's Draft Rules and Regulations for Regulatory Floodplains in Colorado
• Board Meetings - Doc Type: Memo

the remainder of the I OO-year flow. The channel irnprovement shall not cause increased
velocities or erosive forces upstream and downstream of the improvement.
D. Channelization and flow diversion projects shall appropriately consider issues of
sediment transport, erosion, deposition, and channel migration and properly mitigate
potential problems through the project as well as upstream and downstream of any
improvement activity. A detailed geomorphological analysis shall be performed to
assist in determining the most appropriate design.
E. Low-lying areas (below BFE) "protected" by levees, flood fringe areas raised by fill, or
perched flow diversion or channelization projects shall not be considered to be removed
from the I OO-year floodplain for the purpose of building basements.
F. Project proponents for a mitigation activity shall evaluate the residual 100-year
floodplain. Proponents are also encouraged to map the 500-year residual floodplain for
the evaluation of critical facilities.
G. All flood protection and mitigation projects shall be maintained to ensure that they
preserve their structural and hydraulic integrity. Annual inspections including, as
appropriate, field surveys of stream cross-sections, shall demonstrate to the appropriate
regulatory jurisdictions that the project features are in satisfactory structural condition,
the adequate flow capacity remains available for conveying flood flows, that no
encroachment by vegetation, animals, geological processes such as erosion, deposition,
or rnigration, or by human activity, endanger the proper function of the project. If any
significant problems are noted in such annual inspections, the local regulatory
jurisdiction shall notify the CWCB within 30 days of said problems.
H. Stream alteration activities proposed by a project proponent shall be evaluated for its
impact on the regulatory floodplain and shall be in compliance with all applicable
codes, ordinances, rules, regulations and laws.
1. Stream alteration activities shall be designed and sealed by a Colorado registered
professional engineer in good standing.
J. Stream alteration activities shall be properly permitted by local, state and federal
agencies and shall be in conformance with FEMA floodplain regulations (44 C.F.R.).
K. Stream alteration activities may be constructed only after the project proponent
demonstrates through a floodway analysis and report, sealed by a Colorado registered
professional engineer, that there are no adverse floodway and floodplain impacts
resulting from the project.
L. No adverse floodway impact means a O.O-foot rise in the proposed conditions versus
existing conditions floodway. Proposed increases to the regulatory 100-yearflood
profile and floodplain shall require notification to, and acceptance by, all affected
property owners.

Rule 12. Process for Desil!nation and Approval of Rel!ulatorv Floodplains:
A. Designation and Approval Requirements. The Board will designate and approve
regulatory floodplains by written resolutions based only upon such floodplain
information as the Board determines meets the standards set forth in these Rules and
Regulations.
B. Base Flood. The 100-year flood shall be the basis for all designation and approvals by
the Board, for zoning purposes, of regulatory floodplains in Colorado.
C. Conditions. All designations and approvals of approximate floodplain information by
the Board shall specify that the community may exercise conditional zoning powers

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