Drought Vulnerability of Illinois' Community Surface Water Systems - Vulnerability, Illinois State Water Survey

Drought Vulnerability Classification

At-Risk System – There is greater than a 10% probability that the current system would not be able to provide the community’s current rate of water demand through a severe drought similar to the drought of record.

Drought Adequacy Description

If a drought similar to the 1953-1955 drought of record were to recur today, it is estimated with 50% confidence that the current system would be able to support a demand of 0.16 mgd (the mid- or best yield estimate). It is estimated with 90% confidence that the current system would be able to support a demand of 0.08 mgd. Because the system would just barely be able to fulfill the community’s current demand of 0.07 mgd with 90% confidence, the drought vulnerability of the system is classified as AT-RISK due to expected increases in demand during a drought.

Additional Notes