06

• Board Meeting Date: 7/11/2007
• Description: Flood Section - Proposed Levee Administration Policy - Board Discussion
• Board Meetings - Doc Type: Memo

, Infrastructure may continue to be developed behind the levee without adequate floodplain
management procedures, a process which inadvertently, and often unknowingly, places this new
development at risk
, Residents are given a false sense of security of protection. Oftentimes these residents do not take
actions to protect themselves, such as carrying flood insurance, because they believe a flood will not
occur due to the presence of the levee.
, In many cases, local and state govemments are blamed when levees become decertified. The result
of this decertification is a new mandatory flood insurance purchase requirement for those residing in
the floodplain, and higher rates when the policy is obtained or renewed. Residents often become
angry because they have not been required to hold a flood insurance policy all along, and they often
don't understand what has changed.

Although levee decertification is a rare occurrence in Colorado to date, there are many levees of various
design standards that are aging and falling into disrepair due to lack of maintenance. Around the country,
numerous levee decertifications are coming to light, and the effects of these decertifications, outlined above,
are best avoided if at all possible.

A final concem regarding the presence of levees is that these flood protection structures are often placed such
that they encroach substantially onto natural river systems and floodplain areas. This creates adverse impacts
both on flood frequency and severity as well as on the natural and beneficial functions of the river system.

Because of the nature of levee failure flooding, the CWCB Flood Protection Staff believes that levees are
typically not a wise community choice and should never be used to protect undeveloped land with the intent
of protecting new development in the flood risk area behind the levee. This sentiment has already been
reflected by the Board in the CWCB's "Rules and Regulations for Regulatory Floodplains in Colorado"
(Rules), approved by the Board on September 12, 2005, in Durango. Rule 17(0) of these Rules states:

"(The following floodplain management activities and actions (are) suggested by the CWCB to
increase a community's overall level of flood protection. Communities and other authorized
govemment entities may)... Prohibit the construction of new levees that are intended to remove
land from a regulatory floodplain for the purpose of allowing new development activity to take
place in areas that are otherwise flood prone."

Many levees already exist in the state, especially in communities that were built along rivers, which were
usually constructed at a time when the community and other assisting agencies believed it could engineer a
truly flood-protected situation. Where levees already exist, or where a levee appears to be the best (or only)
flood protection option after careful analysis of all altematives to mitigated the incidence of flooding to
existing development, the CWCB Flood Protection Staff advocates that levees:
, Must be designed to a high protection standard,
, Must be frequently and adequately inspected, with all needed maintenance funded and performed. If
proper maintenance procedures are not followed, the levee should be treated as nonexistent for
floodplain mapping and management purposes.
, Should be used only as a method of last resort for providing a limited means of flood risk reduction
for existing development; and
, Are inappropriate as a means of protecting undeveloped land for proposed development.

It must be noted that Congress is considering implementation a National Levee Safety Program. Although
the details of this Program are still being worked out, the Board can be assured that recommendations
provided in this memorandum, along with the attached draft levee policy, are consistent with the goals of this
proposed Program. Indeed, adoption of a sound levee policy by the CWCB Board, will place the State of
Colorado in a leadership position when and if this Program is established. It should also give the State a head
start in implementing federally required procedures in the future.

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