40 CFR § 141.521
What updated watershed control requirements must my unfiltered system implement to continue to avoid filtration?
June 9, 2020
Your system must take any additional steps necessary to minimize the potential for contamination by Cryptosporidium oocysts in the source water. Your system's watershed control program must, for Cryptosporidium:
(a) Identify watershed characteristics and activities which may have an adverse effect on source water quality; and
(b) Monitor the occurrence of activities which may have an adverse effect on source water quality.