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

Illinois Drought

Pontiac (Illinois-American)

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 1987-1990 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 2.20 mgd (the mid- or best yield estimate). In Pontiac, both streamflow availability and high nitrate concentrations limit the system’s water supply, as the system also uses its off-channel reservoir for blending when there are high nitrate concentrations in the Vermilion River. It is estimated with 90% confidence that the current system would be able to support a demand of 1.73 mgd. Because the system would not be able to fulfill the community’s current demand of 2.02 mgd with 90% confidence, the drought vulnerability of the system is classified as AT-RISK.

Additional Notes

Population Served:





Vermilion - Illinois

System Information

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Illinois State Water Survey

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Champaign, IL 61820-7463
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