Illinois Administrative Code
Title 35 - ENVIRONMENTAL PROTECTION
Part 604 - DESIGN, OPERATION, AND MAINTENANCE CRITERIA
Subpart B - SOURCE DEVELOPMENT
Section 604.205 - Surface Water Quantity

a) be adequate to meet the maximum projected water demand of the service area as shown by calculations based on a one in 50-year drought or the extreme drought of record, and should include consideration of multiple year droughts;

b) provide a 20% surplus unless otherwise approved by the Agency under Section 604.145(b); and

c) be adequate to compensate for all losses, including silting, evaporation, seepage and required water releases.