| Total Reservoir Volume (a) | Potential for loss of human life (b) | Environmental impact (c) | Socioeconomic impact (d) |
| Small < = 5 million m³ (1) | NONEXISTENT (there are no permanent/resident or temporary/transiting persons in the affected area downstream of the dam) (0) | SIGNIFICANT (affected area of the dam does not represent an area of environmental interest, areas protected under specific legislation or it is totally devoid of its natural conditions) (3) | NONEXISTENT (there are no facilities and navigational services in the area affected by the dam accident) (0) |
| Medium 5 million to 75 million m³ (2) | INFREQUENT (there are no persons permanently occupying the affected area downstream of the dam, but there is a side road of local use) (4) | VERY SIGNIFICANT (affected dam area shows relevant environmental interest or protected under specific legislation) (5) | LOW (there is a small concentration of residential and commercial, agricultural, industrial or infrastructure facilities in the affected dam area or port facilities or navigational services) (4) |
| Large 75 million to 200 million m³ (3) | FREQUENT (there are no persons permanently occupying the affected area downstream of the dam, but there is a municipal, state, federal or other local highway and/or possible building of potential permanence of persons that may be affected) (8) | - | HIGH (there is a large concentration of residential and commercial, agricultural, industrial facilities, leisure and tourism infrastructure and services in the affected area of the dam or port facilities or navigational services) (8) |
| Very large >200 million m³ (5) | EXISTING (there are persons permanently occupying the affected area downstream of the dam, therefore human lives may be affected) (12) | - | - |