Ill. Admin. Code tit. 35, § 378.302 – Cumulative Effects of Multiple Sources

a) When modeling fecal coliform die-off, the permittee must account for contributions of additional downstream sources. Requests for exemption will be denied when die-off modeling indicates that the combined effect of multiple sources will lead to fecal coliform water quality violations of 35 Ill. Adm. Code 302.209 or 302.306.
b) In reviewing any request for exemption, the Agency shall re-examine previously modified NPDES permits when modeling indicates that there is a potential for fecal coliform water quality violations of 35 Ill. Adm. Code 302.209 or 302.306 due to the combined effects of:
1. 1) the source's modified fecal coliform limits;
2. 2) the permittee's modified fecal coliform limits; and
3. 3) any new source.