In 2005, the USACE started Screening for Portfolio Risk Analysis (SPRA). This analysis screened every one of the approximately 692 dams in the USACE inventory based on available information, to expeditiously identify and classify the highest risk dams requiring urgent and compelling action (Dam Safety Action Classification Classes I and II Dams). This screening has yielded a clear but basic understanding of where the greatest risks and priorities are located.
Completing SPRA has allowed USACE to develop a Portfolio Investment Plan for more than 300 dams within the portfolio determined to be “actionable,” or posing moderate to extremely high risks.
The Dam Safety Action Classification System (DSAC) is intended to provide consistent and systematic guidelines for appropriate actions to address the dam safety issues and deficiencies of USACE dams. USACE dams are placed into a DSAC class based on their individual dam safety risk considered as a combination of probability of failure and potential life safety, economic, environmental, or other consequences. The DSAC table presents different levels and urgencies of actions that are commensurate with the different classes of the safety status of USACE dams. These actions range from immediate recognition of an urgent and compelling situation requiring extraordinary and immediate action for unsafe dams through normal operations and dam safety activities for safe dams.
DSAC Class I (Urgent and Compelling) – Dams where progression toward failure is confirmed to be taking place under normal operations and the dam is almost certain to fail under normal operations within a time frame from immediately to within a few years without intervention; or, the combination of life or economic consequences with probability of failure is extremely high.
DSAC Class II (Urgent) – Dams where failure could begin during normal operations or be initiated as the consequence of an event. The likelihood of failure from one of these occurrences, prior to remediation, is too high to assure public safety; or, the combination of life or economic consequences with probability of failure is very high.
DSAC Class III (High Priority) – Dams that have issues where the dam is significantly inadequate or the combination of life, economic, or environmental consequences with probability of failure is moderate to high.
DSAC Class IV (Priority) – Dams are inadequate with low risk such that the combination of life, economic, or environmental consequences with a probability of failure is low and the dam may not meet all essential USACE engineering guidelines.
DSAC Class V (Normal) – Dams considered adequately safe, meeting all essential agency guidelines and the residual risk is considered tolerable.