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

Drought Vulnerability Classification

Adequate System – There is greater than a 90% probability that the community will not experience any water shortages or threat thereof during a severe drought similar to the drought of record.

Drought Adequacy Description

If 50-year drought conditions were to occur today, it is estimated with 50% confidence that the current system would be able to support a demand of 14.1 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 10.5 mgd. Because the system would be able to fulfill the community’s current demand with 90% confidence, the drought vulnerability of the system is classified as ADEQUATE.

Additional Notes