35 Ill. Adm. Code 604.205
Surface Water Quantity
Section 604.205Â Surface Water Quantity
The quantity of surface water at the source must:
a)Â Â Â Â Â Â Â Â 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)Â Â Â Â Â Â Â Â provide
a 20% surplus unless otherwise approved by the Agency under Section 604.145(b);
and
c)Â Â Â Â Â Â Â Â be
adequate to compensate for all losses, including silting, evaporation, seepage
and required water releases.