FLOOD10053

• County: Statewide
• Community: State of Colorado
• Basin: Statewide
• Title: A Study to Identify Attitudes and Problems with Integrating Floodplain Management and Dam Safety
• Date: 8/1/1984
• Prepared For: University of Denver
• Prepared By: Stephen A. Spann
• Floodplain - Doc Type: Educational/Technical/Reference Information

6

reservoir dams are classified according to the consequences

of

dam failure.

The criteria used for classification are

1 i sted below:

1. Hioh Hazard Dam: The failure of the dam would
reasonably cause loss of human life.

2. Moderate Hazard Dam: The failure of the dam would
cause significant damage to improved properties. but
would not cause loss of life.

3. Low Hazard: The failure of the dam would result
only in the loss of the dam.1

While the spillway design

flood

criteria for a

reservoir dam is not specifically dependent upon the hazard

classification. the

state has taken

a dim view of

the

.

potential failure of the dam whether it would

be caused

by

large inflow floods or by structural faults.

In keeping with

this philosophy. the following is the state policy concerning

spillway design:

The inflow design flood for a reservoir is the
probable maximum flood. However. it may be smaller
than a probable maximum flood provided it can be
shown that the incremental damagesdue to failure of
the dam are insignificant and will not cause loss
of life....
...A minor dam situated in a remote area, where loss
of life or property damage is not envisioned....
the spillway must safely pass the 100-year
flood.'"

The basis for the policy is two fold.

First. the dam

owner has total liability for all property damages caused by

the failure of his dam during a rainstorm unless he can show

1Stephen A. Spann. "Design Engineer Project Manual
for Submitting Plans and Specifications for the Construction
of Reservoir bams." December 28. 1983. Office of the State
Engineer, Denver, Colorado, p. 9.

"'Ibid. p. A-5