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

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RULE 6

STANDARDS FOR DELINEATON OF REGULATORY FLOODLAIN INFORMATION

This Rule contains standards for approximate and detailed regulatory floodplain determinations for the State of
Colorado by all study contractors. This Rule and its subsections within each rule are supported by technical
standards and specifications herein and additional technical standards that will be located in the attached
Appendices: Appendix A - Base Mapping, Appendix B - Hydrology, and Appendix C - Hydraulics.

RULE 7 STANDARDS FOR REGULATORY FLOODW AYS

This Rule presents a minimum standard for the incorporation of floodway delineations within regulatory
floodplains to assist communities in their floodplain management activities, The 1988 Rules and Regulations are
silent regarding this very important and nationally utilized floodplain administration tool.

RULES

CRITERIA FOR DETERMINING THE EFFECTS OF DAMS ON REGULA TORY
FLOODPLAINS

This Rule addresses flood control dams (e.g., the Chatfield Dam and Reservgir in Littleton, Colorado} and non-
flood control dams (e.g., ABC Dam and Reservoir in Anywhere, Colorado). Colorado has over two. thousand
dams and reservoirs that vary in size from less than one acre-foot of storage to many thousands of acre-'-feet of
storage. Many of the on-stream structures can have an influence on the determination of a 1 DO-year floodplain. .
In addition, many of these dams and reservoirs can provide downstream flood protection in their operational
planning and operations.

CRITERIA FOR DETERMINING EFFECTS OF LEVEES ON REGUATORY
FLOODPLAINS

This Rule defines how levees must be considered when determining the limits of a regulatory floodplain. The
rule addresses conditions for levee engineering, operation, maintenance and ownership.

RULE 9

RULE 10

STORMW ATER DETENTION

This Rule presents startdards when a detention structUre can be considered for basin hydrology considerations.
A detention facility can mitigate the effects of development activities on downstream runoff characteristics and
patterns. Certain irrigation facilities can provide a level of detention when operated in harmony with the owner
and government.

EFFECTS OF FLOOD MITIGATION MEASURES AND STREAM ALTERATION
ACTIVITIES ON THE REGULATORY FLOODPLAINS

This Rule recognizes that flood mitigation measures and stream alteration activities will take place within
. Colorado streams and floodplains. These actions, when properly designed, constructed and administered, can
provide multiple benefits to many interests. If improperly designed, constructed and administered, these actions
can Increase flooding impacts. These actions must be considered in the Floodplain Rules since they normally
impact and take place within regulatory floodplains,

RULE 12 PROCESS FOR DESIGNATION AND APPROVAL OF REGULATORY
FLOODPLAINS

RULE 11

This Rule outlines the process and procedure for Board consideration of a floodplain request for designation and
approval of a regulatory floodplain. A Board consideration of a floodplain request will be considered by a .
formal community request or by Board initiative when Board action is deemed to be in the best interest of the
public.

RULE 13 DESIGNATION AND APPROVAL OF CHANGES TO REGULATORY
FLOODPLAINS

This Rule acknowledges that changes to a previous Board floodplain designation action can occur. This Rule
provides. the procedures for the consideration of a revision or amendment to a previous designation and approval
action by the Board.

Flood Protection. Water Project Planning and Finance. Stream and Lake Protection
Water Supply Protection. Conservation Planning.

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