Precipitation departures for sites across Illinois experiencing their driest a) 1 year, b) 2 years, c) 3 years, d) 5 years, and e) 10 years, expressed as percent of normal (1971-2000) precipitation. Source: The Water Cycle and Water Budgets in Illinois: A Framework for Drought and Water-supply Planning by Derek Winstanley et al., Illinois State Water Survey IEM 2006-02.
