16 ‎(2)‎

• Board Meeting Date: 9/18/2007
• Description: Flood Section - Proposed Levee Administration Policy
• Board Meetings - Doc Type: Memo

SUBJECT:

CWCB STATEWIDE LEVEE POLICY

ST A TEWIDE LEVEE POLICY

EFFECTIVE DATE: September 19,2007

PURPOSE:

POLICY:

APPICABILITY:

PROCEDURE:

To discourage the constmction of new levees as flood protection measures,
and to encourage proper maintenance of existing levees.

The use of levees for property protection, flood control, and flood hazard
mitigation is not encouraged by the CWCB, unless other mitigation
alternatives are not cost-effective or viable. In situations where levees are the
only viable alternative for protection of existing development, "setback"
levees should be designed and constmcted to maintain the natural channel
and reserve a portion of the natural floodplain capacity. The CWCB does not
endorse the use of levees for flood protection along streams or watercourses
where new development is planned. For existing levees that protect existing
development, proper maintenance should be performed by levee
owners/operators, or non-federal sponsors in the case of federal levees,
according to a published maintenance plan or Operations & Maintenance
(O&M) manual that ensures continuing proper function of the stmcture.

This policy applies to all proposed man-made embankments that are intended
to provide flood protection from flood flow events up to and including the
design storm event. This policy also applies to existing levees protecting
existing development. Levees are typically designed to provide a specific
level of protection along the stream reach of interest. They can be overtopped
or fail during flood events larger than the design flood event, and can also
deteriorate over time due to lack of proper maintenance and inattention to
necessary upgrades based on watershed hydrology and other factors. When
levees do fail, they usually fail catastrophically. The resulting damage caused
by a levee failure may be more significant than damage caused if the levee
was not in place. Levees do not provide full or unlimited protection from
flooding to the people and property that they were designed to protect.
Constmction and ownership of levees carries potential liability concerns that
levee owners/operators may not be fiscally able to accept.

In cases where new levees are determined to be the only feasible mitigation
alternative, their design and constmction must comply with the Colorado
Floodplain and Stormwater Criteria Manual, Chapter 13, Section 4. (CWCB).
Existing levees should be maintained by their owners/operators following
accepted maintenance procedures, and a formal maintenance plan or O&M
manual should be published and adhered to.

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