The Dam Safety Program conducts periodic safety inspections of non-federal, non-hydroelectric dams to determine their condition and the extent, if any, to which they pose a potential or actual threat to life and property. The Department’s current policy is to inspect only those dams that are capable of impounding more than 500,000 cubic feet. An inspection report with recommendations is provided to the owner and also kept on file by the Dam Safety Program. The frequency of inspections or return interval is based upon the hazard class of a dam, the higher the hazard the more often the dam is inspected. The hazard class is based upon the potential of damage or loss of life if the dam were to fail and is not related to the condition of the dam, which could be an indication of the potential to fail. A dam’s classification may change from what it was when it was built or at the last inspection because of changes in downstream conditions if some houses are built downstream that could be impacted by a failure. The classification could also change (either up or down) if a more detailed breach analysis is carried out that more accurately determines downstream damage potential.
The Downstream Hazard Classification system used by the Department is same as the U.S. Army Corps of Engineers system given in Recommended Guidelines for Safety Inspection of Dams (ER 1110-2-106, 25 Sept. 79, 24 Mar 80 Chg 1).
|Class||Hazard Category||Potential Loss of Life||Potential Economic Loss||Inspection Frequency|
|3||Low||None expected (No permanent structures for human habitation)||Minimal (Undeveloped to occasional structures or agriculture)||5-10 years|
|2||Significant||Few (No urban developments and no more than a small number of inhabitable structures)||Appreciable (Notable agriculture, industry or structures)||3-5 Years|
|1||High||More than few||Excessive (Extensive community, industry or agriculture)||1 Year (Annually)|
The inspection program is voluntary on the part of the dam owners. Before an inspection is made, a diligent effort will be made to contact the landowner for access permission. The landowner may deny permission for inspection. See the Inspection of Dams document for more information on dam inspections and hazard classification.