35 Ill. Adm. Code 301.270
Dilution Ratio
Section 301
Section 301.270Â Dilution
Ratio
"Dilution Ratio" means
the ratio of the seven-day once in ten year low flow of the receiving stream or
the lowest flow of the receiving stream when effluent discharge is expected to
occur, whichever is greater, to the average flow of the treatment works for the
design year.